Return to the Container Gardening Forum

 o
Container Soils - Water Movement and Retention XVIII

Posted by tapla z5b-6a mid-MI (My Page) on
Thu, Jan 23, 14 at 16:16

Container Soils - Water Movement and Retention XVIII
I first posted this thread back in March of '05. So far, it has reached the maximum number of posts GW allows to a single thread seventeen times, which is much more attention than I ever imagined it would garner. I have reposted it in no small part because it has been great fun, and a wonderful catalyst in the forging of new friendships and in increasing my list of acquaintances with similar growing interests. The forum and email exchanges that stem so often from the subject are in themselves enough to make me hope the subject continues to pique interest, and the exchanges provide helpful information. Most of the motivation for posting this thread another time comes from the reinforcement of hundreds of participants over the years that strongly suggests the information provided in good-spirited collective exchange has made a significant difference in the quality of their growing experience. I'll provide links to some of the more recent of the previous dozen threads and nearly 2,500 posts at the end of what I have written - just in case you have interest in reviewing them. Thank you for taking the time to examine this topic - I hope that any/all who read it take at least something interesting and helpful from it. I know it's long. My hope is that you find it worth the read, and the time you invest results in a significantly improved growing experience.

Since there are many questions about soils appropriate for use in containers, I'll post basic mix recipes later, in case any would like to try the soil. It will follow the information.

Before we get started, I'd like to mention that I wrote a reply and posted it to a thread recently, and I think it is well worth considering. It not only sets a minimum standard for what constitutes a 'GOOD' soil, but also points to the fact that not all growers look at container soils from the same perspective, which is why growers so often disagree on what makes a 'good' soil. I hope you find it thought provoking:

Is Soil X a 'Good' Soil?

I think any discussion on this topic must largely center around the word "GOOD", and we can broaden the term 'good' so it also includes 'quality' or 'suitable', as in "Is soil X a quality or suitable soil?"

How do we determine if soil A or soil B is a good soil? and before we do that, we'd better decide if we are going to look at it from the plant's perspective or from the grower's perspective, because often there is a considerable amount of conflict to be found in the overlap - so much so that one can often be mutually exclusive of the other.

We can imagine that grower A might not be happy or satisfied unless knows he is squeezing every bit of potential from his plants, and grower Z might not be happy or content unless he can water his plants before leaving on a 2-week jaunt, and still have a weeks worth of not having to water when he returns. Everyone else is somewhere between A and Z; with B, D, F, H, J, L, N, P, R, T, V, X, and Y either unaware of how much difference soil choice can make, or they understand but don't care.

I said all that to illustrate the large measure of futility in trying to establish any sort of standard as to what makes a good soil from the individual grower's perspective; but let's change our focus from the pointless to the possible.

We're only interested in the comparative degrees of 'good' and 'better' here. It would be presumptive to label any soil "best". 'Best I've found' or 'best I've used' CAN sometimes be useful for comparative purposes, but that's a very subjective judgment. Let's tackle 'good', then move on to 'better', and finally see what we can do about qualifying these descriptors so they can apply to all growers.

I would like to think that everyone would prefer to use a soil that can be described as 'good' from the plant's perspective. How do we determine what a plant wants? Surprisingly, we can use %s established by truly scientific studies that are widely accepted in the greenhouse and nursery trades to determine if a soil is good or not good - from the plant's perspective, that is. Rather than use confusing numbers that mean nothing to the hobby grower, I can suggest that our standard for a good soil should be, at a minimum, that you can water that soil properly. That means, that at any time during the growth cycle, you can water your plantings to beyond the point of saturation (so excess water is draining from the pot) without the fear of root rot or compromised root function or metabolism due to (take your pick) too much water or too little air in the root zone.

I think it's very reasonable to withhold the comparative basic descriptor, 'GOOD', from soils that can't be watered properly without compromising root function, or worse, suffering one of the fungaluglies that cause root rot. I also think anyone wishing to make the case from the plant's perspective that a soil that can't be watered to beyond saturation w/o compromising root health can be called 'good', is fighting on the UP side logic hill.

So I contend that 'good' soils are soils we can water correctly; that is, we can flush the soil when we water without concern for compromising root health/function/metabolism. If you ask yourself, "Can I water correctly if I use this soil?" and the answer is 'NO' ... it's not a good soil ... for the reasons stated above.

Can you water correctly using most of the bagged soils readily available? 'NO', I don't think I need to point to a conclusion.

What about 'BETTER'? Can we determine what might make a better soil? Yes, we can. If we start with a soil that meets the minimum standard of 'good', and improve either the physical and/or chemical properties of that soil, or make it last longer, then we have 'better'. Even if we cannot agree on how low we wish to set the bar for what constitutes 'good', we should be able to agree that any soil that reduces excess water retention, increases aeration, ensures increased potential for optimal root health, and lasts longer than soils that only meet some one's individual and arbitrary standard of 'good', is a 'better' soil.

All the plants we grow, unless grown from seed, have the genetic potential to be beautiful specimens. It's easy to say, and easy to see the absolute truth in the idea that if you give a plant everything it wants it will flourish and grow; after all, plants are programmed to grow just that way. Our growing skills are defined by our ability to give plants what they want. The better we are at it, the better our plants will grow. But we all know it's not that easy. Lifetimes are spent in careful study, trying to determine just exactly what it is that plants want and need to make them grow best.

Since this is a soil discussion, let's see what the plant wants from its soil. The plant wants a soil in which we have endeavored to provide in available form, all the essential nutrients, in the ratio in at which the plant uses them, and at a concentration high enough to prevent deficiencies yet low enough to make it easy to take up water (and the nutrients dissolved in the water). First and foremost, though, the plant wants a container soil that is evenly damp, never wet or soggy. Giving a plant what it wants, to flourish and grow, doesn't include a soil that is half saturated for a week before aeration returns to the entire soil mass, even if you only water in small sips. Plants might do 'ok' in some soils, but to actually flourish, like they are genetically programmed to do, they would need to be unencumbered by wet, soggy soils.

We become better growers by improving our ability to reduce the effects of limiting factors, or by eliminating those limiting factors entirely; in other words, by clearing out those influences that stand in the way of the plant reaching its genetic potential. Even if we are able to make every other factor that influences plant growth/vitality absolutely perfect, it could not make up for a substandard soil. For a plant to grow to its genetic potential, every factor has to be perfect, including the soil. Of course, we'll never manage to get to that point, but the good news is that as we get closer and closer, our plants get better and better; and hopefully, we'll get more from our growing experience.

In my travels, I've discovered it almost always ends up being that one little factor that we willingly or unwittingly overlooked that limits us in our abilities, and our plants in their potential.

Food for thought:
A 2-bit plant in a $10 soil has a future full of potential, where a $10 plant in a 2-bit soil has only a future filled with limitations. ~ Al

Container Soils - Water Movement & Retention

As container gardeners, our first priority should be to ensure the soils we use are adequately aerated for the life of the planting, or in the case of perennial material (trees, shrubs, garden perennials), from repot to repot. Soil aeration/drainage is the most important consideration in any container planting. Soils are the foundation that all container plantings are built on, and aeration is the very cornerstone of that foundation. Since aeration and drainage are inversely linked to soil particle size, it makes good sense to try to find and use soils or primary components with particles larger than peat/compost/coir. Durability and stability of soil components so they contribute to the retention of soil structure for extended periods is also extremely important. Pine and some other types of conifer bark fit the bill nicely, but I'll talk more about various components later.

What I will write also hits pretty hard against the futility in using a drainage layer of coarse materials in attempt to improve drainage. It just doesn't work. All it does is reduce the total volume of soil available for root colonization. A wick can be employed to remove water from the saturated layer of soil at the container bottom, but a drainage layer is not effective. A wick can be made to work in reverse of the self-watering pots widely being discussed on this forum now.

Consider this if you will:

Container soils are all about structure, and particle size plays the primary role in determining whether a soil is suited or unsuited to the application. Soil fills only a few needs in container culture. Among them are: Anchorage - a place for roots to extend, securing the plant and preventing it from toppling. Nutrient Retention - it must retain a nutrient supply in available form sufficient to sustain plant systems. Gas Exchange - it must be amply porous to allow air to move through the root system and gasses that are the by-product of decomposition to escape. Water - it must retain water enough in liquid and/or vapor form to sustain plants between waterings. Air - it must contain a volume of air sufficient to ensure that root function/metabolism/growth is not impaired. This is extremely important and the primary reason that heavy, water-retentive soils are so limiting in their affect. Most plants can be grown without soil as long as we can provide air, nutrients, and water, (witness hydroponics). Here, I will concentrate primarily on the movement and retention of water in container soil(s).

There are two forces that cause water to move through soil - one is gravity, the other capillary action. Gravity needs little explanation, but for this writing I would like to note: Gravitational flow potential (GFP) is greater for water at the top of the container than it is for water at the bottom. I'll return to that later.

Capillarity is a function of the natural forces of adhesion and cohesion. Adhesion is water's tendency to stick to solid objects like soil particles and the sides of the pot. Cohesion is the tendency for water to stick to itself. Cohesion is why we often find water in droplet form - because cohesion is at times stronger than adhesion; in other words, water's bond to itself can be stronger than the bond to the object it might be in contact with; cohesion is what makes water form drops. Capillary action is in evidence when we dip a paper towel in water. The water will soak into the towel and rise several inches above the surface of the water. It will not drain back into the source, and it will stop rising when the GFP equals the capillary attraction of the fibers in the paper.

There will be a naturally occurring "perched water table" (PWT) in containers when soil particulate size is under about .100 (just under 1/8) inch. Perched water is water that occupies a layer of soil at the bottom of containers or above coarse drainage layers that tends to remain saturated & will not drain from the portion of the pot it occupies. It can evaporate or be used by the plant, but physical forces will not allow it to drain. It is there because the capillary pull of the soil at some point will surpass the GFP; therefore, the water does not drain, it is said to be 'perched'. The smaller the size of the particles in a soil, the greater the height of the PWT. Perched water can be tightly held in heavy (comprised of small particles) soils where it perches (think of a bird on a perch) just above the container bottom where it will not drain; or, it can perch in a layer of heavy soil on top of a coarse drainage layer, where it will not drain.

Imagine that we have five cylinders of varying heights, shapes, and diameters, each with drain holes. If we fill them all with the same soil mix, then saturate the soil, the PWT will be exactly the same height in each container. This saturated area of the container is where roots initially seldom penetrate & where root problems frequently begin due to a lack of aeration and the production of noxious gasses. Water and nutrient uptake are also compromised by lack of air in the root zone. Keeping in mind the fact that the PWT height is dependent on soil particle size and has nothing to do with height or shape of the container, we can draw the conclusion that: If using a soil that supports perched water, tall growing containers will always have a higher percentage of unsaturated soil than squat containers when using the same soil mix. The reason: The level of the PWT will be the same in each container, with the taller container providing more usable, air holding soil above the PWT. From this, we could make a good case that taller containers are easier to grow in.

A given volume of large soil particles has less overall surface area when compared to the same volume of small particles and therefore less overall adhesive attraction to water. So, in soils with large particles, GFP more readily overcomes capillary attraction. They simply drain better and hold more air. We all know this, but the reason, often unclear, is that the height of the PWT is lower in coarse soils than in fine soils. The key to good drainage is size and uniformity of soil particles. Mixing large particles with small is often very ineffective because the smaller particles fit between the large, increasing surface area which increases the capillary attraction and thus the water holding potential. An illustrative question: How much perlite do we need to add to pudding to make it drain well?

I already stated I hold as true that the grower's soil choice when establishing a planting for the long term is the most important decision he/she will make. There is no question that the roots are the heart of the plant, and plant vitality is inextricably linked in a hard lock-up with root vitality. In order to get the best from your plants, you absolutely must have happy roots.

If you start with a water-retentive medium, you cannot effectively amend it to improve aeration or drainage characteristics by adding larger particulates. Sand, perlite, Turface, calcined DE ...... none of them will work effectively. To visualize why sand and perlite can't change drainage/aeration, think of how well a pot full of BBs would drain (perlite); then think of how poorly a pot full of pudding would drain (bagged soil). Even mixing the pudding and perlite/BBs together 1:1 in a third pot yields a mix that retains the drainage characteristics and PWT height of the pudding. It's only after the perlite become the largest fraction of the mix (60-75%) that drainage & PWT height begins to improve. At that point, you're growing in perlite amended with a little potting soil.

You cannot add coarse material to fine material and improve drainage or the ht of the PWT. Use the same example as above & replace the pudding with play sand or peat moss or a peat-based potting soil - same results. The benefit in adding perlite to heavy soils doesn't come from the fact that they drain better. The fine peat or pudding particles simply 'fill in' around the perlite, so drainage & the ht of the PWT remains the same. All perlite does in heavy soils is occupy space that would otherwise be full of water. Perlite simply reduces the amount of water a soil is capable of holding because it is not internally porous. IOW - all it does is take up space. That can be a considerable benefit, but it makes more sense to approach the problem from an angle that also allows us to increase the aeration AND durability of the soil. That is where Pine bark comes in, and I will get to that soon.

If you want to profit from a soil that offers superior drainage and aeration, you need to start with an ingredient as the basis for your soils that already HAVE those properties, by ensuring that the soil is primarily comprised of particles much larger than those in peat/compost/coir/sand/topsoil, which is why the recipes I suggest as starting points all direct readers to START with the foremost fraction of the soil being large particles, to ensure excellent aeration. From there, if you choose, you can add an appropriate volume of finer particles to increase water retention. You do not have that option with a soil that is already extremely water-retentive right out of the bag.

I fully understand that many are happy with the results they get when using commercially prepared soils, and I'm not trying to get anyone to change anything. My intent is to make sure that those who are having trouble with issues related to soil, understand why the issues occur, that there are options, and what they are.

We have seen that adding a coarse drainage layer at the container bottom does not improve drainage. It does though, reduce the volume of soil required to fill a container, making the container lighter. When we employ a drainage layer in an attempt to improve drainage, what we are actually doing is moving the level of the PWT higher in the pot. This simply reduces the volume of soil available for roots to colonize. Containers with uniform soil particle size from top of container to bottom will yield better and more uniform drainage and have a lower PWT than containers using the same soil with added drainage layers.

The coarser the drainage layer, the more detrimental to drainage it is because water is more (for lack of a better scientific word) reluctant to make the downward transition because the capillary pull of the soil above the drainage layer is stronger than the GFP. The reason for this is there is far more surface area on soil particles for water to be attracted to in the soil above the drainage layer than there is in the drainage layer, so the water perches. I know this goes against what most have thought to be true, but the principle is scientifically sound, and experiments have shown it as so. Many nurserymen employ the pot-in-pot or the pot-in-trench method of growing to capitalize on the science.

If you discover you need to increase drainage, you can simply insert an absorbent wick into a drainage hole & allow it to extend from the saturated soil in the container to a few inches below the bottom of the pot, or allow it to contact soil below the container where the earth acts as a giant wick and will absorb all or most of the perched water in the container, in most cases. Eliminating the PWT has much the same effect as providing your plants much more soil to grow in, as well as allowing more, much needed air in the root zone.

In simple terms: Plants that expire because of drainage problems either die of thirst because the roots have rotted and can no longer take up water, or they suffer/die because there is insufficient air at the root zone to insure normal root function, so water/nutrient uptake and root metabolism become seriously impaired.

To confirm the existence of the PWT and how effective a wick is at removing it, try this experiment: Fill a soft drink cup nearly full of garden soil. Add enough water to fill to the top, being sure all soil is saturated. Punch a drain hole in the bottom of the cup and allow the water to drain. When drainage has stopped, insert a wick into the drain hole . Take note of how much additional water drains. Even touching the soil with a toothpick through the drain hole will cause substantial additional water to drain. The water that drains is water that occupied the PWT. A greatly simplified explanation of what occurs is: The wick or toothpick "fools" the water into thinking the pot is deeper than it is, so water begins to move downward seeking the "new" bottom of the pot, pulling the rest of the water in the PWT along with it. If there is interest, there are other simple and interesting experiments you can perform to confirm the existence of a PWT in container soils. I can expand later in the thread.

I always remain cognizant of these physical principles whenever I build a soil. I have not used a commercially prepared soil in many years, preferring to build a soil or amend one of my 2 basic mixes to suit individual plantings. I keep many ingredients at the ready for building soils, but the basic building process usually starts with conifer bark and perlite. Sphagnum peat plays a secondary role in my container soils because it breaks down too quickly to suit me, and when it does, it impedes drainage and reduces aeration. Size matters. Partially composted conifer bark fines (pine is easiest to find and least expensive) works best in the following recipes, followed by uncomposted bark in the <3/8" range.

Bark fines of pine, fir or hemlock, are excellent as the primary component of your soils. The lignin contained in bark keeps it rigid and the rigidity provides air-holding pockets in the root zone far longer than peat or compost mixes that too quickly break down to a soup-like consistency. Conifer bark also contains suberin, a lipid sometimes referred to as nature's preservative. Suberin, more scarce as a presence in sapwood products and hardwood bark, dramatically slows the decomposition of conifer bark-based soils. It contains highly varied hydrocarbon chains and the microorganisms that turn peat to soup have great difficulty cleaving these chains - it retains its structure.

Note that there is no sand or compost in the soils I use. Sand, as most of you think of it, can improve drainage in some cases, but it reduces aeration by filling valuable macro-pores in soils. Unless sand particle size is fairly uniform and/or larger than about BB size, I leave it out of soils. Compost is too fine and unstable for me to consider using in soils in any significant volume as well. The small amount of micro-nutrients it supplies can easily be delivered by one or more of a number of chemical or organic sources that do not detract from drainage/aeration.

The basic soils I use ....

The 5:1:1 mix:

5 parts pine bark fines, dust - 3/8 (size is important
1 part sphagnum peat (not reed or sedge peat please)
1-2 parts perlite (coarse, if you can get it)
garden lime (or gypsum in some cases)
controlled release fertilizer (if preferred)

Big batch:
2-3 cu ft pine bark fines
5 gallons peat
5 gallons perlite
2 cups dolomitic (garden) lime (or gypsum in some cases)
2 cups CRF (if preferred)

Small batch:
3 gallons pine bark
1/2 gallon peat
1/2 gallon perlite
4 tbsp lime (or gypsum in some cases)
1/4 cup CRF (if preferred)

I have seen advice that some highly organic (practically speaking - almost all container soils are highly organic) container soils are productive for up to 5 years or more. I disagree and will explain why if there is interest. Even if you were to substitute fir bark for pine bark in this recipe (and this recipe will long outlast any peat based soil) you should only expect a maximum of two to three years life before a repot is in order. Usually perennials, including trees (they're perennials too) should be repotted more frequently to insure they can grow at as close to their genetic potential within the limits of other cultural factors as possible. If a soil is desired that will retain structure for long periods, we need to look more to inorganic components. Some examples are crushed granite, fine stone, VERY coarse sand (see above - usually no smaller than BB size in containers, please), Haydite, lava rock (pumice), Turface, calcined DE, and others.

For long term (especially woody) plantings and houseplants, I use a superb soil that is extremely durable and structurally sound. The basic mix is equal parts of screened pine bark, Turface, and crushed granite.

The gritty mix:

1 part uncomposted screened pine or fir bark (1/8-1/4")
1 part screened Turface
1 part crushed Gran-I-Grit (grower size) or #2 cherrystone
1 Tbsp gypsum per gallon of soil (eliminate if your fertilizer has Ca)
CRF (if desired)

I use 1/8 -1/4 tsp Epsom salts (MgSO4) per gallon of fertilizer solution when I fertilize if the fertilizer does not contain Mg (check your fertilizer - if it is soluble, it is probable it does not contain Ca or Mg. If I am using my currently favored fertilizer (I use it on everything), Dyna-Gro's Foliage-Pro in the 9-3-6 formulation, and I don't use gypsum or Epsom salts in the fertilizer solution.

If there is interest, you'll find some of the more recent continuations of the thread at the links below:

Post XVII

Post XVI

Post XV

Post XIV

Post XIII


If you feel you were benefited by having read this offering, you might also find this thread about Fertilizing Containerized Plants helpful.

If you do find yourself using soils you feel are too water-retentive, you'll find some Help Dealing with Water Retentive Soils by following this embedded link.

If you happen to be at all curious about How Plant Growth is Limited, just click the embedded link.

Finally, if you are primarily into houseplants, you can find an Overview of the Basics that should provide help in avoiding the most common pitfalls.

As always - best luck. Good growing!! Let me know if you think there is anything I might be able to help you with.

Al


Follow-Up Postings:

 o
RE: Container Soils - Water Movement and Retention XVIII

Al - probably going to try both your mixes.

While I don't doubt for a moment the value of well drained mix like this, I have my concerns.

Even using Miracle Gro, I had plants last summer that were "snug" but not rootbound (meaning the rootball did fill the container, but only just), that would be watered Day 1 in the morning, and were actually wilted by the end of Day 2. I don't have the time to water 3 times a day! I have a day job, a wife, kids, etc, etc.

I am concerned such a well drained mix would leave me with wilted, half-dead plants once summer heat kicks in.


 o
RE: Container Soils - Water Movement and Retention XVIII

Great info

This post was edited by TheMasterGardener1 on Fri, Jan 24, 14 at 9:37


 o
RE: Container Soils - Water Movement and Retention XVIII

Even using Miracle Gro, I had plants last summer that were "snug" but not rootbound ...
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
That is the inherent nature of container gardening.
It is not just because of the medium used, but also pot size, climate .. are some of the limitations. As you mentioned, even a more moisture retentive medium (like MG) might not be able to deal with it as you would like.

Knowing all that, I have a plant to do some container growing this season, in bark based( Al's 5-1-1) medium. And I am prepared to water and fertilize more often, AS NEEDED.
as they say, YOU CANNOT HAVE YOUR CAKE AND EAT IT TOO !


 o
RE: Container Soils - Water Movement and Retention XVIII

I don't MIND watering more, but I can't quit my job and sit on a lawn chair with a hose in my hand all day, either.

Nobody has been able to tell me how much they end up having to water.


 o
RE: Container Soils - Water Movement and Retention XVIII

The concepts herein are not designed for convenience... they require a watchful eye, but are absolutely workable and useful to the optimum growth of containerized plants. The concepts follow basic science and physics of growing within confined spaces.

I have used both basic medium recipes, and have made some tweaks of my own to suit my individual environment, and I've been extremely happy with the results.

It's really the concepts that are important to think critically about... they make solid sense in the scheme of container growing.


 o
RE: Container Soils - Water Movement and Retention XVIII

Good info - I definitely will try it. It might take some experimentation to get right but I'm sure I can come up with a solution.


 o
RE: Container Soils - Water Movement and Retention XVIII

Al,

Congratulations on yet another new thread full of good information! Who would have believed there would be 18 threads on this topic?

Goes to show how popular you and your soil mixes are on this site.

TYG


 o
RE: Container Soils - Water Movement and Retention XVIII

I really enjoy experimenting with soil. I grow so many different plants I need all kinds of soil. Fast draining to slow draining. Water retentive to anti water retentive. I have so many situations to consider. Plants are so different. Some plants like wet feet, others you can let the roots dry for months in the open air. Trying to meet all these conditions that vary so much has been a challenge. A lot of fun too!!
Containers is only one aspect for me. I have raised beds and in ground plantings too. And how to maximize conditions in all these various environments is what I thrive on, so much fun, and keeps me out of trouble. I've learned so much about conserving our environment and materials, to preparation of foods produced. It's all connected.
From planting a seed to the best marinara sauce one could make. I get to buy new tools like dehydrators, and roasters, and the best pruning shears made, to discovering methods of propagation, and seed saving, and the breeding of hybrids. It's been a fun ride! One discovers that getting there is not really the goal, the journey is the prize.


 o
RE: Container Soils - Water Movement and Retention XVIII

Hair, I think most people water their 5-1-1 pots every 3-5 days on avg. Maybe once a week in winter and every couple of days in hot summer depending on where you live and how much sun the pot gets.

You should acquaint yourself with the wooden skewer method of gauging irrigation frequency. Do a search in this forum.


 o
RE: Container Soils - Water Movement and Retention XVIII

On a side note - what do you do with your "old" mixes (of any type) when they're no longer usable?


 o
RE: Container Soils - Water Movement and Retention XVIII

5-1-1 gets tossed/spread out on the lawn or in the garden.

I haven't had my Gritty "expire" yet, but I may try to salvage the grit from the bark and turface.


 o
RE: Container Soils - Water Movement and Retention XVIII

I can always use my old mix. Say, that it is MG Potting Soil. I can use some of it in place of peat moss or pine fine. That is basically what MG PS is with some perlite ..and time release fertilizer, maybe some calcium and magnesium. I have a bag and half of it that I am going to use as I said. If noting else you can dump it in your garden.


 o
RE: Container Soils - Water Movement and Retention XVIII

Hi Al,

I also want to congratulate you on another turning point for this wealth of information!

You always give great advise and always answer everyone's questions and do so until he/ she understands. You are a wonderful person giving your time and your knowledge to others trying to better their growing abilities.

I was so fortunate to have met you and all of the other great people who always take time to answer and also give advise as well.

Thank you, my friend! You are awesome!!!

Keep up the great work!!!

Please... We need this to be a " sticky". Maybe if people leave a comment for GW they will listen to us. This is very important not to have it at the top so everyone can learn the wealth of information.

My plants and I thank you!!! ;-)

I have included a pic of my Adenium that just loves the Gritty Mix.. One of many trees that love this and the 5-1-1

Have a wonderful evening!

Laura


 o
RE: Container Soils - Water Movement and Retention XVIII

Hello!
I have couple questions to ask.
But before that, I have to thank you for the WEALTH of inndepth and clear information you've provided everyone with these threads. I've been researching for years and just now have I seen these threads.
And here are my questions :)

1) How important is container choice when it comes to aeration and water retention.
The idea of PWT and water accumilation at the bottom of the pot makes sense with a plastic pot but what about terracotta pots? I know that terracotta pots tend to dry out quicker because of their porosity but does that do any good in diminishing the affects of the PWT? Also, what's the case with "grow bags" that air-prune roots? Do these kinds of containers help reduce or eliminate the PWT because they allow the water to escape more readily through the lining of the container or through evaporation?

2) Second question is your thoughts on soil inoculated with a well balanced microbial system as described in an article at The Permaculture Research Institute.
Check out a Permaculture Inspired Soil System: http://permaculturenews.org/2013/11/25/introduction-naturalised-nursery-practice/

3) Related to the latter link, how about adding earthworms to the soil mix you suggested. Could they help in providing some compost for the plants to use?

4) What kind of organic fertilizer do you recommend using for growing vegetables in the 5:1:1 mix?

5) And finally! (Hope I haven't lost you) I've read that biochar can effectively be used as an alternative to perlite (plus it could possibly be more sustainable). Could it possibly be better than perlite because it seems to have more pores? Check this out: http://lib.dr.iastate.edu/etd/13399/

Thanks Al and anyone else who'd like to reply!

This post was edited by GeoDe on Sat, Jan 25, 14 at 8:20


 o
RE: Container Soils - Water Movement and Retention XVIII

Hello!
I a have couple questions to ask.
But before that, I have to thank you for the WEALTH of inndepth and clear information you've provided everyone with these threads. I've been researching for years and just now have I seen these threads.
And here are my questions :)

1) How important is container choice when it comes to aeration and water retention.
The idea of PWT and water accumilation at the bottom of the pot makes sense with a plastic pot but what about terracotta pots? I know that terracotta pots tend to dry out quicker because of their porosity but does that do any good in diminishing the affects of the PWT? Also, what's the case with "grow bags" that air-prune roots? Do these kinds of containers help reduce or eliminate the PWT because they allow the water to escape more readily through the lining of the container or through evaporation?

2) Second question is your thoughts on soil inoculated with a well balanced microbial system as described in an article at The Permaculture Research Institute.
Check out a Permaculture Inspired Soil System: http://permaculturenews.org/2013/11/25/introduction-naturalised-nursery-practice/

3) Related to the latter link, how about adding earthworms to the soil mix you suggested. Could they help in providing some compost for the plants to use?

4) What kind of organic fertilizer do you recommend using for growing vegetables in the 5:1:1 mix?

5) And finally! (Hope I haven't lost you) I've read that biochar can effectively be used as an alternative to perlite (plus it could possibly be more sustainable). Could it possibly be better than perlite because it seems to have more pores? Check this out: http://lib.dr.iastate.edu/etd/13399/

Thanks Al and anyone else who'd like to reply!

This post was edited by GeoDe on Sat, Jan 25, 14 at 8:23


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sat, Jan 25, 14 at 14:47

First - thanks to all for the kind comments. The main reason I hang out at GW is because I enjoy the feeling I'm helping other growers expand on the amount of satisfaction they can get from the growing experience. I remember how I struggled through a lot of adversity in the beginning, almost all of it soil-related. Because I had so many soil issues, I knew others must be dealing with them too, so I decided to write something to help them avoid all the pitfalls I fell into at first. Someone upthread said the journey is the prize, but because so many battle frustration and struggle against poor soils when they first start gardening in containers, I see the journey as less rewarding, by far, than waking to the idea your struggles are behind you, which in my estimation is the culmination of your efforts.

HM4Evr - How often every plant needs watering will vary by the size of the plant and the degree to which roots have colonized the soil mass. One thing that's nice though, is the fact you can water on a schedule when using soils that support little perched water. For example, I have over 100 plants in the basement under lights and in the gritty mix. About 95 of them get watered every 4 days, and they're all in shallow pots. The remaining 5 or so, because they are in such tiny pots, get watered every other day. The succulents I grow at work (all in the gritty mix, get watered every Friday. My old soils go on the compost pile, get spread on the raised beds, or get tossed, depending on what soil we're talking about & how full of soil the beds are. Old 5:1:1 always finds a place other than the trash.

Thanks Laura - your comments were especially nice, and much appreciated. I think it would be really cool if they decided to make the thread a sticky, but I'll leave that to you guys and GW to decide. I always enjoy the pics you share - they illustrate how well you understand growing in containers and your dedication to their care.

GeoD -

1) How important is container choice when it comes to aeration and water retention.
The idea of PWT and water accumulation at the bottom of the pot makes sense with a plastic pot but what about terracotta pots? I know that terracotta pots tend to dry out quicker because of their porosity but does that do any good in diminishing the affects of the PWT? Also, what's the case with "grow bags" that air-prune roots? Do these kinds of containers help reduce or eliminate the PWT because they allow the water to escape more readily through the lining of the container or through evaporation?
I think the OP on this thread is an attempt to address all of these questions. Container SIZE choice will always be important because roots need room. What material the container is made of affects plant health to the extent that containers with porous sides offer better gas exchange, and therefore more potential for a healthy root system. Soil choice also impacts the importance of your choice of container. IOW, you wouldn't do too well if you use a 4" deep pot with a soil that supports 4" of perched water, because at container capacity the soil will be 100% saturated. When using water retentive soils, deeper pots offer more potential, as do pots with gas-permeable walls, which ensure a faster of air to the soil mass due to the water vapor that passes through the walls.

Like pots with their soil mass in contact with the earth, grow bags help eliminate PWTs by virtue of the earth's wicking action. Set a grow bag on concrete and it is more like a pot - set it on the ground and it acts like a mini raised bed, due to the wicking effect of the earth.

2) Second question is your thoughts on soil inoculated with a well balanced microbial system as described in an article at The Permaculture Research Institute. I read enough of the article to see that that person is looking to naturalize conditions in an unnatural environment. "Feed the soil - not the plant" works very well for plants in situ, but for ex situ applications (containers), not so well. Containers are an environment hostile to the proliferation of large populations of soil life. In some ways, that might even be a good thing, because soil life incrementally destroys soil structure, simply by virtue of the fact it exists in the soil.

Do some experimentation for yourself & see what you think. With the way I grow, I can be assured that all the nutrients essential to normal growth are in the soil in the right ratio and at a concentration that assures the plant will have what it wants whenever it wants it. I think that is exactly what our goal would be if we were to define it. I don't see an easy SURE way of arriving at that goal by depending on the soil to feed the plant. I think the article clearly illustrates the author was working within the limits of an ideology, so was limited in choices. There is nothing wrong with that, as long as we recognize the self-limiting nature of that ideology.

3) Related to the latter link, how about adding earthworms to the soil mix you suggested. Could they help in providing some compost for the plants to use? Again, if that's the approach you'd like to take, by all means, pursue it. I don't think this thread will help you much, though. It doesn't make a lot of sense to go out of your way to focus on a soil because of the structural advantages it offers, only to add biota that will eliminate the reason for your focus. You can grow perfectly healthy plants in a bucket of broken glass, if you're willing to water (fertigate) every hour or so.

4) What kind of organic fertilizer do you recommend using for growing vegetables in the 5:1:1 mix? I don't know. As you can see, I'm not big on fertilizers for containers that can't be counted on to deliver all the nutrients plants need, when they need them. An organic fertilizer might be dependent on feather meal, for example, as its primary N source. So when will the N be available? When it's warm/cool enough, moist enough, and soil biotic populations are high enough to break the feathers down into elemental forms the plant can assimilate. For me, soluble synthetic fertilizers offer the surest and easiest way of putting nutrients in the plant.

Whatever you decide on for a fertilizer, try to make sure you have all the nutrients covered. Many fertilizers, organic AND synthetic, lack one or several of the essentials likely to be deficient w/o supplementation.

5) And finally! (Hope I haven't lost you) I've read that bio-char can effectively be used as an alternative to perlite (plus it could possibly be more sustainable). Could it possibly be better than perlite because it seems to have more pores? I didn't see anything important in the thesis that hasn't been discussed on the Container Gardening forum and by dozens of other authors. Charcoal doesn't have any magical properties. It doesn't cleanse the soil of impurities or provided anything significantly different than perlite. I've said many times that if you would like to use charcoal, use it as a replacement for perlite in the 5:1:1. I would think its porosity would depend on what type of tree it came from, and in part on its particle size.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

I want to add my thanks to you, Al, for all the knowledge and experience you have shared on Gardenweb over these many years. You are truly a master teacher. And on top of that, you have provided a place where hundreds have been able to learn together, share ideas, ask questions and grow together. It's been so much fun!

I started using gritty mix and 5-1-1 about three years ago, and I cannot say enough about how well these mixes have improved my results inside and outside.

I'd also like to address one of the questions that often comes up when people first learn about these mixes: how often do you need to water your containers using one of the mixes? My answer is "way less than you imagine." Remember, more plants are killed by overwatering than under watering. But with these mixes, it is very hard to overwater. With little or no perched water table, plants in either mix can hold up to weeks of drenching rain.

I grow a wide range of different veggies in containers of 5-1-1 in the summer, and don't need to water any of them more often than every other day, even huge tomato plants during a heat wave. And yet those same tomatoes can withstand a rainy season when they are tiny in a 25-gallon pot.

I have about 50 house plants and small trees in gritty mix that I water about twice a week at the height of summer outdoors, but only water about once every two weeks indoors during winter.

One key is using containers that are large enough that your plants don't become root bound.


 o
RE: Container Soils - Water Movement and Retention XVIII

I know overwatering is more a concern, except that the plants I was speaking about - in just those 2 days, the MG mix would be bone-dry and shrunken away from the sides of the container, and the plant wilted - so I'm certain it was too LITTLE water that was the issue.

I'll take your word on Al's mixes though and try them myself.


 o
RE: Container Soils - Water Movement and Retention XVIII

HM4ever: What kind of plant were you growing? How big was the plant and how large was the container? Are you sure all of the MG in the pot was saturated after watering? A problem you can have with peat-based mixes like Miracle Gro is that there can be pockets of dry mix that is hydrophobic. I think it would be very unusual for all the mix in the pot to dry out to the point that it pulls away from the sides of the pot that quickly unless the plant was root bound.

I am not sure what you mean when you say your plant was "snug but not root bound." If you can lift the plant out of the pot and the soil comes out in one piece with many roots showing on the sides, it needs to be in a larger pot.


 o
RE: Container Soils - Water Movement and Retention XVIII

The specific plant was a marigold my son grew at school. There were roots on the sides but only a few.

It was about a 1 gallon size pot, the plant was about twice the width of the pot.


 o
RE: Container Soils - Water Movement and Retention XVIII

Is Redwood ok to use for bark?


 o
RE: Container Soils - Water Movement and Retention XVIII

We recommend that you avoid redwood bark.
It usually has a hairy, fibrous texture that tends to compact, hold excess moisture, and change the drainage dynamics of a container. It results in a very inconsistent mix, and may have chemical properties that are unfavorable, as well.

The best bark is Pine, followed closely by Fir. Some folks have used Spruce and Hemlock (Tsuga), but those barks aren't as commonly available.

Josh


 o
RE: Container Soils - Water Movement and Retention XVIII

Gotcha. Going to be on the lookout for Pine bark. Hey Greenman, since you live in Norcal, maybe you have similar stores there as I do here in Socal. Could you give me some possible places to find good Pine Bark? My biggest concern is getting one that has been dyed or has had something added to it and is not intended for potting mixes.


 o
RE: Container Soils - Water Movement and Retention XVIII

Hey! I use a product called Greenall Micro Bark.
It is actually produced by the parent company E.B. Stone, whose product line should be available all throughout California. The bark is Douglas Fir bark, which is much more common in our corner of the West.

Josh


 o
RE: Container Soils - Water Movement and Retention XVIII

Is it OK to use Miracle Gro Moisture Control (since I have it on hand) instead of straight peat for the peat portion of 5-1-1-?


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Tue, Feb 11, 14 at 12:55

Yes


 o
RE: Container Soils - Water Movement and Retention XVIII

Good: I have also a bag of MG MC from last year. So I will mix it in sparingly (not too much. "Moisture Control" means that it retains more moisture, longer.) so too much of it can defeat the purpose of 5-1-1, I would think.


 o
RE: Container Soils - Water Movement and Retention XVIII

Is there a difference between Cherry Stone's Traction Grit and #2 Poultry Grit? Both are fairly easy to find around here and I've always used the Traction Grit but I figured I'd make sure before I buy another batch.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Wed, Feb 12, 14 at 17:10

I'm not sure, but my guess is the traction grit probably isn't screened as carefully as the #2 cherrystone.

You could call them:

TCC Materials

2025 Centre Pointe Blvd, Suite 300
Mendota Heights, MN 55120
(651) 688-9116

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

Thanks for the info, I will do that.

Another unrelated question: I know you recommend using a wick for heavier and more water-retentive soils but is there any circumstance that you'd recommend it for the gritty mix?
For example, I have always noticed that tipping a pot forward with the gritty will almost always yield more water pouring out after the initial watering drainage has stopped. I have all my pots raised above the ground, ie. no saucers.
Is this perched water something to worry about, requiring a wick?


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Wed, Feb 12, 14 at 17:53

If the mix is screened properly, you shouldn't really need a wick, but even if a wick was overkill, it certainly wouldn't put you at a disadvantage.

How much water - and from what volume of soil when you tip the pot?

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

I have the opposite problem with my cookie-cutter Gritty. I get niagara falls out the bottom and sometimes wonder if any water stays up in the mix. :)


 o
RE: Container Soils - Water Movement and Retention XVIII

Tapla,
Is a 5-1-1 mix appropriate for noncontainer growing such as a small square foot raised bed?


 o
RE: Container Soils - Water Movement and Retention XVIII

Is the bottom of the bed enclosed or resting open on the ground? Can you post up a pic of this small raised bed?


 o
RE: Container Soils - Water Movement and Retention XVIII

Don't get me wrong, it's instant Niagara falls for me too when I water, and the surface of the gritty looks dry within an hour or two. But after it's done with the initial draining/dripping (I'm talking even hours after), I can tip any sized pot forward and get a constant single stream of water, especially with the larger sized pots. The length of time/amount of water dripping seems proportional to the pot's size. It doesn't take long to fully drain, maybe a few seconds for smaller pots and up to a minute with the larger pots. I could measure the amount of extra water coming out next time if that helps.

All the pots are different sized plastic with multiple holes. Holes in each pot are about 1/3" wide, large enough to need drywall tape to screen the holes of the gritty materials. With the pot elevated, and before tipping it forward, I can usually see water cohesion in the holes, like a drop forming. If I put my finger up to it, usually water will drip down my hand, kind of like a wicking effect. It's as if the water cohesion prevents the last bit of water from emptying.

I'm sure it's nothing too much to worry about but I figure any perched water is not desirable and I figured I'd make sure this isn't a common occurrence. Thanks for the info!


 o
RE: Container Soils - Water Movement and Retention XVIII

Well, some of the particles in Gritty may be right on that 1/8" size boundary between perching and no perching. I'll check out my Gritty pots next time I water to see if they do the same thing. I always assumed (perhaps wrongly) that there was no perched water at all given the flow-through, but now you have me thinking.


 o
RE: Container Soils - Water Movement and Retention XVIII

Oxboy,
I have the materials but haven't built it yet, the reason I was asking is that I believe I've seen mention of the 511 mix on other forums besides this one.


 o
RE: Container Soils - Water Movement and Retention XVIII

In my mind, it all hinges on whether you add a bottom or not and need this mini raised bed to be portable. If you have a bottom, it will act like a container and 5-1-1 is appropriate. If you have no bottom and the mini-raised bed mix sits right on turf or soil, the roots will eventually grown down into that soil. In addition, you won't have perched water concerns.

5-1-1 is really built for contained systems. You have a fair amount more leeway with bottomless pots resting on bare soil. You can still use 5-1-1 but it might not be worth the expense and effort if you can just mix up a more pedestrian mix of say native soil, compost/peat mix and some hard particles to give it structure and longevity.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Wed, Feb 12, 14 at 21:41

Lucille - If you're growing in a raised bed (RB) - no matter how large or small, you'll probably want something heavier than the 5:1:1 mix. By 'heavier', I mean something that tends to hold more water. As others mentioned, with the earth acting as a wick, you wont have to be worried about perched water. If you're using RBs because of heavy clay, you'll maybe want to talk about things a little more. If the soil under the beds drains reasonably well, you're good to go.

Soil from my raised beds:
 photo misc057.jpg
It's very productive - great tilth - can plunge an arm into it a foot deep.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

Thank you Oxboy and Al. I will use a heavier mix for the raised beds, and 5-1-1 for the large pots I ordered.
That's some beautiful soil you got there Al.


 o
RE: Container Soils - Water Movement and Retention XVIII

Al, that looks like really quality soil.. What soil did you fill the beds with? Do you mulch? What do you fertilize with? Im curious because I know your perspective on containers, what do you do on the outdoor garden? My guess is you probably work hand to hand with microbes out there, huh?

Al, you said something that worries me.. You said something along the lines of "soil microorganisms ruin soil structure". This is only the case when you garden unnaturally in containers. Whereas, the organisms break down the larger particles into smaller particles, almost creating a mush.. This mush is actually compost/hummus. Outside, in plants natural habit, where they grew up and adapted to for eons, been relying of soil microorganisms to provide soil structure, nutrients, and a host of other beneficial things to plants. Plants couldn't live without microorganisms.

I understand, Al, that you are most likely aware of this. But, some people who consider you the "container guru" will read your post " soil microbes ruin soil structure" and be against soil microbes. When soil microbes been the basis of soil/plant life for eons.. It's just a rare case that soil microbes are a disadvantage, that is, if you are growing unnaturally.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Mon, Feb 17, 14 at 11:37

I'm not usually someone who would say that soil organisms ruin soil structure unless I qualify the statement or the context in which it was used was so clear that qualification probably wasn't necessary.

Let me take a second to say that I'm not bound by a particular ideology. What works best, is easiest, and has the widest margin for error is the route I take. I have found that container gardeners that limit themselves to practices whereby they are trying to use their container media to feed the plant, a practice born of the adage "feed the soil - not the plant' or variations thereof, usually have a much tougher row to hoe than gardeners who focus on ensuring their soils offer a structurally favorable home for roots and bear the responsibility for nutrition on their own shoulders.

I rarely fertilize my gardens or beds. I live in what used to be bottomland of the Saginaw Valley watershed, so my soil was a rich loam when I got here, with the mulching over the last 30 years improving it even further. I make a little compost, which I use, but I mulch every other year with about 2-3" of fine pine bark.

So, yes - for me there is a clear delineation between what works best in the garden and what works best in containers - two different types of culture with different approaches. If you're depending on the materials your soil is made of to feed the plant, you'll need material that breaks down quickly - and you'll still need to supplement. As the soil particles break down, aeration decreases and water retention increases, both of which are problems. Using materials that provide good structure for the intended life of the planting and fertilizing with something you know will provide nutrition reliably (the amount needed when needed) simply makes the most sense to me.

Growers who choose to grow this way can always get reliable help because of how simple the relationship between soil choice, watering, and fertilizing is. People who try to utilize the soil to feed the plant can't get the same simplified advice because everything is quite complicated. You never know how much of what (nutritionally speaking) the plant is getting, or when; the ability to water correctly is affected by the breakdown of soil particles; and the ability to fertilize efficiently is affected by the inability to water properly.

There is no right or wrong way to garden in containers, but there is an easy and a hard way.

Al



 o
RE: Container Soils - Water Movement and Retention XVIII

Thanks for clarifying Al!


 o
RE: Container Soils - Water Movement and Retention XVIII

I just measured the water that came out after tilting three of the pots. I'm not sure of the pots' volume but two of them are labeled as 8" and the other a 12".
About an hour after watering and no dripping, about 2.5oz came out of the 8 and 4.5oz came out of the 12.
Anything to worry about there?


 o
RE: Container Soils - Water Movement and Retention XVIII

The myth of PERCHED WATER TABLE:

When we talk about PWT in pots( no Earth geology here) it has a clear definition: AND it is a constant ,( more or less), for any given potting mix.

To understand and visualize this, lets say that you have filled a 5-gal. bucket(all the way to the rim, with a given 5-1-1 mix( remember that not anything that is called 511 is the same).
Now put that bucket in a big flat, 10" container, holding about 2 gallons of water.
Now,(assuming that bucket has hols at the bottom) it will start sucking the water in/up. This is called "Wicking", "Osmotic Action" or "Capillary Action".
Given enough time, the contents in the bucket will get wet, up to a certain height. This height is called "PERCHED WATER TABLE" for that particular potting mix.

Let me give you an example: I bottom water my seedlings. Some of them are about 8" tall. And the potting mix consists of " pine fines, coir/peat, vermiculite and some perlite.
After letting the pot to sit in a pan of water, it gets wet all the way to the top. So this tells me that this particular mixture has a minimum of 8 inch PWT. If I had to put this out in the rains, it will never dry up. But as a houseplant with a programmed watering it is not a problem.

THE MORAL: The role of pine nuggets in the 511 is to interrupt capillary/wicking action and reduce this PWT. Otherwise we might just as well use peat moss, This principle is further employed and dramatized by adding gravel(gritty) and things like turface, which have very little or no capillary action properties.

JUST MY TAKE & OPINION>


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Tue, Feb 18, 14 at 15:32

That's close, but not quite accurate. Water will wick upward higher than the ht of the PWT.

To determine the ht of the PWT, the soil is completely saturated then allowed to drain until it stops. The height of the completely saturated soil = the ht of the PWT, and that WILL be constant in pots of any size or shape.

Individual particles with tiny air spaces have greater capillary attraction than the sum of the soil's parts, so once the maximum ht of the PWT is limited by the force of gravity pushing down on the water column, soil pores with less capillary attraction can no longer be filled, but the individual particles can still pull water from smaller pore to smaller pore to hts greater than the ht of the PWT.

So soils that support 4" of perched water might be able to wick water to much greater hts - say 8" for example.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

I've read a lot of these threads. Not all 18 iterations, but perhaps a third. Thank you Al for sharing so many thoughts through the lengthy Q&A style. That's a lot of time to read just a third of it, let alone type out all those answers.

Until today, even after reading so much, I was still not clear about what exactly the pine bark fines were like. Perhaps it would benefit noobs like myself if some photos could be incorporated into the OP.

Al: "the middle pile is what my dry 5:1:1 looks like when done"

Al: "For the 5:1:1 mix, dust to 3/8 is best, but if you have some 1/2" pieces in there, don't sweat it."

Al:"What you see at the top is ideal for the 5:1:1 mix."


 o
RE: Container Soils - Water Movement and Retention XVIII

Al: Have you considered chopped coconut husk as a replacement for bark in your gritty mix, or even as part of a 5:1:1? I searched the threads, and only found one serious reference to it (thread XVI) where Ohiofem summarily dismissed it as "different". Otherwise it seems to be lacking in discussion. While it is rather sponge-like, I don't recall it being all too different from bark products in this respect. And the large square size would provide for many macro-pores in the mix.

When raising reptiles, and needing a moist substrate for tropical species, chopped coconut husk (not the peat-like coir fiber), was the only good choice. I would never have considered pine bark as it would decompose or mold, and could not retain it's structure nearly as well as coconut. It would seem that the resistance to degradation would make it a good candidate for the bulk of a long-lived properly draining mix.

Thoughts? Why is it offered for orchid mixes, but not considered more throughly in this series of threads?

I'm going to see if I still have one of the compressed 2cf bales, and might do a side-by-side comparison with pine bark for a couple of the blueberry plants I'm going to be putting in 15 gal pots this spring.


 o
RE: Container Soils - Water Movement and Retention XVIII

I'm sure Al will be along, but since you mentioned my comment (which I don't remember) I'd like to chime in. I tried both coconut husk chips (CHCs) and coir and had problems with them, which I won't go into here. There have actually been quite a few discussions of CHCs and coir on Gardenweb, but the search function here isn't very good. You can find older posts better by using Google to search GW. I just Googled the term "site: Gardenweb.com coconut husk chips vs pine bark" and found a discussion where Al explains what happened when he used CHCs in 5-1-1.

Here is a link that might be useful: Coconut husk chips vs pine bark


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Thu, Feb 20, 14 at 15:36

I've actually posted quite frequently about both coir and CHCs. There are issues inherent in these products that make them less than spectacular as a significant fraction of container media. They have a pH high enough that it precludes the use of dolomite as a liming and as a source of Ca and Mg. They are very high in their K content, which needs to be taken into account, and they are often very high in salinity as a result of having been processed using seawater.

Here is a copy/paste job from something I wrote on another thread:

Peat vs. Coir
Sphagnum peat and coir have nearly identical water retention curves. They both retain about 90-95% of their volume in water at saturation and release it over approximately the same curve until they both lock water up so tightly it's unavailable for plant uptake at about 30-33% saturation. Coir actually has less loft than sphagnum peat, and therefore, less aeration. Because of this propensity, coir should be used in mixes at lower %s than peat. Because of the tendency to compact, in the greenhouse industry, coir is primarily used in containers in sub-irrigation (bottom-watering) situations. Many sources produce coir that is high in soluble salts, so this can also be an issue.

Using coir as the primary component of container media virtually eliminates lime or dolomitic lime as a possible Ca source because of coir's high pH (6+). Gypsum should be used as a Ca source, which eliminates coir's low S content. All coir products are very high in K, very low in Ca, and have a potentially high Mn content, which can interfere with the uptake of Fe. Several studies have also shown that the significant presence of phenolic allelochemicals in fresh coir can be very problematic for a high % of plants, causing poor growth and reduced yields.

I haven't tested coir thoroughly, but I have done some testing of CHCs (coconut husk chips) with some loose controls in place. After very thoroughly leaching and rinsing the chips, I made a 5:1:1 soil of pine bark:peat:perlite (which I know to be very productive) and a 5:1:1 mix of CHCs:peat:perlite. I planted 6 cuttings of snapdragon and 6 cuttings of Coleus (each from the same plant to help reduce genetic influences) in containers (same size/shape) of the different soils. I added dolomitic lime to the bark soil and gypsum to the CHC soil. After the cuttings struck, I eliminated all but the three strongest in each of the 4 containers. I watered each container with a weak solution of MG 12-4-8 with STEM added at each watering, and watered on an 'as needed basis', not on a schedule. The only difference in the fertilizer regimen was the fact that I included a small amount of MgSO4 (Epsom salts) to provide MG (the dolomitic lime in the bark soil contained the MG, while the gypsum (CaSO4) in the CHC soil did not. This difference was necessary because or the high pH of CHCs and coir.) for the CHC soil.

The results were startling. In both cases, the cuttings grown in the CHC's exhibited < 1/2 the biomass at summers end as the plants in the bark mix.
I just find it very difficult for a solid case to be made (besides "It works for me") for the use of coir or CHC's. They're more expensive and more difficult to use effectively. The fact that some believe peat is in short supply (no where near true, btw) is easily offset by the effect of the carbon footprint of coir in its trek to the US from Sri Lanka or other exotic locales.

That's the view from here. YMMV

Below, you'll find a link to a coir study that you can probably assume applies to CHCs as well (if it doesn't mention CHCs). Someone posted it to a thread and I saved it because it very closely parallels what I either noted in my comparisons or found while researching WHY I saw what I saw.

SUMMARY:

These studies show that coconut coir should be used with great caution. Although the Sri Lanka brands performed better than the Mexican brands, no brand performed consistently better than sphagnum peat. Some species tolerate coir better than others. The addition of calcium sulfate to the media did not have a consistently beneficial effect on growth and in some cases it reduced growth. The best growth in coir media occurred in the Grow Coir® brand. We are continuing these studies to determine the underlying causes of poor plant growth in coir.

Take care - good luck!!

Here is a link that might be useful: Coir study


 o
RE: Container Soils - Water Movement and Retention XVIII

Saw some posts above discussing what to do with the mixes once they've run their course - so how do you know when your gritty mix needs to be replaced? Is there some difference you'll see? Or is it simply based on time?

And has anyone found a good way to separate the crushed granite from the other two? It should still be reusable, right? Thanks in advance to tapla and everyone else that shares their information.


 o
RE: Container Soils - Water Movement and Retention XVIII

Mostly time (3 or 4 yrs), but the bark and turface pieces can look a little mushy/depleted after a few years. You'll get to a point when the Gritty just won't look "fresh" any more and you'll want to replace.

Dump the old gritty in a container full of water. Keep what sinks, discard what floats.


 o
RE: Container Soils - Water Movement and Retention XVIII

"I just find it very difficult for a solid case to be made (besides "It works for me") for the use of coir or CHC's."

I actually can't think of a better reason for using something than 'it works'.
I'm trying some coir this year. I've heard the warnings but have seen first hand accounts of people who are delighted with it.

Plenty of room in the universe for everyone to give different materials and techniques a try.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Fri, Feb 21, 14 at 18:05

You'll find I've given quite a bit of consideration to the phrase "It works for me" because I've encountered it as an argument so many times. I can think of much better reasons to do something than someone saying "It works for me", like "This is exactly why something will work well or exactly why something won't, followed by a concise explanation that is grounded in what we already know about the plant sciences.

People trying coir aren't exactly trailblazers - it's been tried before and a lot has been written about it in commercial journals and books about plant production. I only discovered that AFTER the dismal results I got using coir and CHCs and went looking for reasons. I found out for myself, so I shared in the hope I might save someone some hassle, but I guess it doesn't pain me much that someone else needs to find out for herself, too.

It Works for Me …. or, The Story of Ol’ Joe Pye

There’s this story I often tell ‘bout a real good friend I had a while back - called hisself Joe Pye. Now ol’ Joe was kind of a stubborn sort, but at least sometimes he'd listen ...... if you caught him on a good day. Well, I’m gittin off the track here, so lemme git back to my story.

Ol' Joe had a real peculiar habit. See, ever’ mornin he'd commence to banging his head against the wall for 15 minutes or so before he went to work. When I'd ask him, "Why o' why do you do that, ol' Joe?" His answer would always be, "well it works for me - wakes me up inna mornin. Gits my blood a movin‘"

Now I'd been around the block a time or two; and I was sure there was a more productive way for ol' Joe to wake hisself up inna mornin, so I timed it to when I figgered Joe would be in one of his listenin’ moods, and sorta half whispered a suggestion to him. Had to do it more'n a coupla times, too - even got some other folks agreein with me and telling’ ol’ Joe the same thing … to sorta help ol’ Joe along.
Well by gosh, through the blessed power of multiple suggestions, ol' Joe starts in to huggin & kissin on his wife ever’ morning’ afore work instead of pursuin his other long time habit of bangin his head on that wall. Stubborn as he was, ol’ Joe recognized right away he was better off - he just lacked the benefit of enough experience to see it at first. His wife was quite pleased with the change as well - took right kindly to it. Ol' Joe never ever did go back to bangin his head on that wall neither.


There's a moral to this here yarn: If yer real happy with how things is goin, and ‘it works for you’, by all means, please maintain the status quo; but at least allow it is possible there’s a better way you might not know about .... at least consider it …. please?

“It works for me” says nothing about the comparative quality/value of the method/product in question. It simply gives notice that the person using the argument is happy with things as they are and leaves the door open wide to the possibility/probability there are many other methods/products that would work so much better, that the method/product they hold so tightly to could be ridiculous in comparison.

"Every year I ride to Sacramento from Detroit on my bike. I get there very quickly - only takes me about 4 weeks."

"Hmmmm. I took a plane there from Detroit last year. As I remember, it took about 4 hours."

"So! It works for me!"

The logical error in “it works for me” has a name. It’s called Appeal to Tradition and occurs when the assumption is made that something is better or correct simply because it is traditional, or "I‘ve always done it this way". This sort of "reasoning" often has the following form:

A) I’ve always done/used ….. X
B) Therefore X is better or correct

The reasoning is faulty because having done something for a period of time does not make it better than other ideas/products …. If this type of reasoning was valid, it would still have us curing diseases by casting out devils and breaking witches spells.

In fairness, the reverse is also true. Just because an idea is new or different, doesn’t make it better. It seems though, that we’re all very willing to accept this line of thought, but we tend to be more likely to cling tightly to its converse. Again, the reason is, there is no stubbornness to overcome and no damage to the ego as there is in letting go of “it works for me”.

These points are moot IF the person using the fallacy admits that he/she is happy with the way things are because of a lack of interest in improving things because of how they prioritize or some other reason, and admits it’s quite possible, even likely there may be a better way/product.

Finally, if a person presses “it works for me” into argument, he should be able to demonstrate that what is in question has successfully stood up to challenges and tests for a long period of time, AND supply evidentiary offerings that both back the claim and show why the method/product is better than others suggested as superior or potentially superior. “It works for me”, offered as an argument without support, is really not worth the space it occupies on a page.

When you encounter people who hold fast to “it works for me” and offer it as though it should be the end of the debate - please tell them about Joe, and link to this post. ;o)

Al

This post was edited by tapla on Fri, Feb 21, 14 at 18:10


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Fri, Feb 21, 14 at 18:24

Deleted duplication

This post was edited by tapla on Fri, Feb 21, 14 at 20:05


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Fri, Feb 21, 14 at 18:25

Deleted duplication

This post was edited by tapla on Fri, Feb 21, 14 at 20:07


 o
RE: Container Soils - Water Movement and Retention XVIII

Obviously Al since you had to run your (I'm sure well prepared and set aside) response three times, you really aimed to vanquish any opposition to your opinion about peat even though you admit to not testing coir very well.

Which of course means that you were satisfied enough with peat that you saw no need to adequately test coir, or 'it worked for you'.

I believe I will forward this thread to some of the coir companies.


 o
RE: Container Soils - Water Movement and Retention XVIII

I recall when I read up on the topic several years back that correct sourcing for CHC's was critical. A lot of husks are soaked in seawater for processing. This fine if making rope, matts, etc, but not for reptile substrate, and even more unsuitable for most plants.

After reading up on it a little more in relation to plants, I’m reaching the same conclusion again. There appears to be a significant dichotomy between various test results. The USU review linked to above was one side - calling out mostly negative results. But there seems to be plenty of information to the contrary, and not just anecdotal information. Two fairly rigorous studies I came across today in relation to commercial tomato production didn't come out with glowing results, but using straight coir fiber was at least as good as other routinely used products. That certainly is in contradiction to conclusions by USU that they are harmful to plant growth.
See:
Alberta Canada Agriculture and Rural Development
and
U of AZ Comparison of Five Growing Media

Don't overlook that relying on a false negative and failing to recognize it as such can be a form of Appeal to Tradition.

I think CHC and Coir have great potential and could provide benefits that peat and evergreen bark cannot. But it seems their downside is that they are not as reliably beneficial as peat or pine bark, and much worse results may follow their use if they are not properly sourced/prepared.


 o
RE: Container Soils - Water Movement and Retention XVIII

The original question from charina was:
Have you considered chopped coconut husk as a replacement for bark in your gritty mix, or even as part of a 5:1:1?
But the studies cited talk about substituting coir (not chopped coconut husk) for peat in a standard peat-based mix or sawdust.

I suggest that those who want to test using CHCs or coir do so and report back on their results. Hundreds of us have tried the pine bark mixes Al first posted about back in 2005 and reported mostly very good results. What I like about Gardenweb is that many people report on their personal results. What I find less than helpful is when people assert ideas they've never actually tried for themselves and challenge other's experience without personal evidence. And snide comments about duplicate posts caused by Gardenweb software glitches don't contribute to a civil conversation.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by four 9B (near 9a) (My Page) on
    Sat, Feb 22, 14 at 12:58

> Posted by tapla
> more surface area on soil particles for water to be attracted to in the soil above the
> drainage layer than there is in the drainage layer

The sum of areas on mulitfaceted stones is more than area of the container floor,
therefore a coarse layer would not be worse than floor,
if soil volume remains sufficient for intended plant.
The advantage is increased evaporation,
so, I would regard it instead as an evaporation layer.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sat, Feb 22, 14 at 14:10

Four - I'm sorry - I don't understand what you're saying ......

Robin - we have people posting that have "rethought" the gritty mix a number of times w/o ever having made it or tried it. People who simply reject the use of Turface and make broad statements about it, even in the face of large numbers of success stories and the fact they've never actually USED it, because of someone else's comments that don't square with the observations of a LOT of experienced growers.

To be fair, there are a lot of areas in soil science where we can make some pretty reliable predictions. There are also a lot of gray areas that need qualification. When I listen to conversations at GW, I always pay closer attention to those who know the difference between the cut-and-dried areas and the not so cut-and-dried areas ..... and to those who know how to qualify their comments when navigating the not so cut-and-dried material. I made the sentence bold, because credibility is important, and that statement is how we maintain it.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

But the studies cited talk about substituting coir (not chopped coconut husk) for peat in a standard peat-based mix or sawdust.

Back up a bit. I asked about CHC’s. Al responded with comments about both coir fiber (which is the short fiber sections - there is a lot of coir in CHC, and their sourcing is the same) and CHC comments. The link to USU was about coir. The response was in contrast to the USU link. So, where is the disconnect here? There is a logical flow, not a leap. Why poo-poo the fairly rigorous comparative studies that provide a different perspective than the loose review of poorly cited studies? The point is that if there is such a dichotomy of results from well designed comparative tests, then there must be something more at play. Such soil science isn’t as fraught with personal agendas as environmental or political science. And there are studies, peer reviewed, out there that indicate what some of the factors at play are. But it is feeling very much like a different perspective, possible alternatives, potential improvements, are not desired. Your entrenchment is precisely the Appeal to Tradition that Al spoke to at length through allegory. No one is trying to say that 5:1:1 doesn’t work. This was a very simple inquiry, and an attempt to bring additional information to light. No one is trying to defame 5:1:1.

Lets not forget: 5:1:1 and countless other improvements came about as a result of questioning and asking if there might be a better way. Necessity isn’t the only mother of invention.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by saood Saudi - zone 10b/11 (My Page) on
    Sun, Feb 23, 14 at 2:21

Some of you might be aware that I tried my luck with container gardening this season and so far so good. After the initial hiccups, I have been able to get along quite well with my edible gardening endeavors. One of the major contributory to my learning was this very post of Al and I cannot thank him much. Thanks a lot Al.

Moving on I am thinking of trying out Self watering containers. I was just wondering as to why it works and why the water is not being wicked up infinitely and result in root rot. The reason that I came up with and I would need the the experts confirmation / comments over here (including Al if possible) is this

1/ A self watering container is constantly sitting above water and after all the soil in the container has just enough moisture, the water keeps on wicked up until PWT levels are reached. Now since the soil at the bottom is constantly in water, the roots do not grow into that PWT area and remain above that level for entire life cycle of the annuals (veggies) and they keep on getting the moisture and the air at the precise time that they need.

2/ On the other hand if we were to keep a container already having roots reaching the very bottom of it (the container) in a saucer full of water, because of the PWT the water will get wicked in through the drainage holes and getting the plant over watered since the roots in the PWT area will rot.

3/ Now that would mean that to make a very easy self watering container would be to let the container sit in the water saucer (perhaps an inch deep) and the potting soil will wick water up and also maintain that PWT. In order for roots to not reach the PWT area, we must ensure that the saucer is always full of water. (Ofcourse the container should be deep enough to allow for both PWT space and the enough free soil space for the roots)

Am I reasoning it correctly?

Thanks..


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sun, Feb 23, 14 at 11:26

The taller a continuous water column is, the more suction it takes to pull it upward. Another way of looking at it is, the taller the continuous water column, the greater the force of gravity is that pushes downward. Any given soil will support a perched water column to a given depth. Let's say we have a soil that supports 10 cm of perched water. That means that the water can no longer move upward after 10 cm because the force of gravity pushing down on the water column is greater than the capillary pull of the soil at hts >10 cm. However, the individual soil particles have greater capillarity then the soil as a whole, so water can still move upward above the level of perched water due to the greater capillary pull of individual particles, and water can move upward from particle to particle at hts greater than the top of the perched water column.

Also, with any given soil, the perched water column is generally higher in soils that are watered from the top. This is because there is a greater tendency for air pockets to hold onto water once they are flooded than there is for the soil to pull water upward to flood soil pores when the ht of the perched water column is approaching its ht limit.

Roots that grow into the water reservoir are generally not a problem, unless they dry out at some point. The roots that grow into water sources are quite different from those produced in a soil-like or highly aerated medium. Physiologically, you will find these roots to be much more brittle than normal roots due to a much higher percentage of aerenchyma (a tissue with a greater percentage of intercellular air spaces than normal parenchyma).

Aerenchyma tissue is filled with airy compartments. It usually forms in already rooted plants as a result of highly selective cell death and dissolution in the root cortex in response to hypoxic (airless) conditions in the rhizosphere (root zone). There are 2 types of aerenchymous tissue. One type is formed by cell differentiation and subsequent collapse, and the other type is formed by cell separation without collapse ( as in water-rooted plants). In both cases, the long continuous air spaces allow diffusion of oxygen (and probably ethylene) from shoots to roots (or form root to root in some cases) that would normally be unavailable to plants with roots growing in hypoxic media. In fresh cuttings placed in water, aerenchymous tiossue forms due to the same hypoxic conditions w/o cell death & dissolution.
Note too, that under hypoxic (airless - low O2 levels) conditions, ethylene is necessary for aerenchyma to form. This parallels the fact that low oxygen concentrations, as found in water rooting, generally stimulate plants to produce ethylene. For a long while it was believed that high levels of ethylene stimulate adventitious root formation, but lots of recent research proves the reverse to be true. Under hypoxic conditions, like submergence in water, ethylene actually slows down adventitious root formation and elongation.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by saood Saudi Arabia - z10 (My Page) on
    Mon, Feb 24, 14 at 2:40

Thank Al for the response.

While your reply has raised a couple of new questions in my mind, but first things first - Based on your scientific reply, can this be concluded that bottom watering (in the manner as explained above in my first post) can also give the good / similar results as self watering containers?


 o
RE: Container Soils - Water Movement and Retention XVIII

great discussion here..i thought i posted other day..i bet i didnt hit send..duh..:)
the more respectful discussion on container soil/mix the
more i learn and incorporate in my own uses..
my potted tropicals (mostly amorphophallus) certainly did well in my version of 5:1:1 mix last growing season..
i currently have over a dozen in this potting mix now..and
they are doing great..
ive unpotted 2 titanums so far..and the roots,corms look
and did great !!!
i was concerned during the summer 2013 the pots would dry out to much.. (utah here..desert) i did water more frequently..but the plants did super !! much better than when i started couple yrs ago..using as i believe most
amorph growers use..a good potting mix..
the mix just held to much water for to long
much thanks especially to al !!! the MAN !!! :)
thanks to u all for postings..hope to see many many more !!!


 o
RE: Container Soils - Water Movement and Retention XVIII

I've seen in a number of places mention of using plastic screening to keep soil/substrate in the container, which I've been doing. But, it can be pricey, and a bit wasteful sometimes. A number of "popular" guides to repotting plants have recommended using paper coffee filters. Does anyone have thoughts on how that helps or hinders drainage?


 o
RE: Container Soils - Water Movement and Retention XVIII

I didn't like coffee filters when I tried them in pots with gritty mix. I think they slowed down the draining too much. If you think about it, the purpose of a coffee filter is to keep the very fine powdered coffee grounds from passing through. The filter does the same thing to the dust in your mix. I'd rather have that stuff wash out of the pot. I had a similar problem when I used paper towels.

I have been using pieces I cut from a roll of fiberglass insect screen I picked up at a hardware store for repairing windows. It lets the stuff under 1/16th inch through and keeps the rest in the pot. It has an added benefit when I use it outdoors because it keeps pill bugs and slugs out of the pot. Those guys can eat through paper.


 o
RE: Container Soils - Water Movement and Retention XVIII

Two words:

Drywall Tape

Two more words:

Home Depot

Buy it. Cut it. Stick it over your drainage holes. Make sure you get the sturdy kind.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Wed, Mar 5, 14 at 17:29

Laura (from Texas) - if you're following this thread ...... I can't reply to your email unless you include your addy in the body of the message or configure your user page settings so others can reply to your messages. I hope you see this, I know you put a lot of effort into your questions.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

If you use 5-1-1 do you need a wick?


 o
RE: Container Soils - Water Movement and Retention XVIII

Not with the cookie cutter 5-1-1 recipe. If it's altered to be more water retentive, possibly.


 o
RE: Container Soils - Water Movement and Retention XVIII

Thanks.

I bought the ingredients and will put together a test sample for you all to check out.

I'm not sure if my perlite is coarse enough, but the pine bark fines seem to be the right texture and everything else (peat moss from Canada, dolomitic lime not hydrolized) seems to fit the bill.


 o
RE: Container Soils - Water Movement and Retention XVIII

Why don't you post some pictures of the bark fines and perlite just in case before you start?


 o
RE: Container Soils - Water Movement and Retention XVIII

Al, rather than resurrecting a very old thread, I thought it better to ask a clarifying question here. In relation to growing fruit trees in a fabric pot set directly on the ground, you wrote:
Almost anything will work for your application. You could even use 40% garden soil, 40% sand, 20% compost. The earth will act as a giant wick, so perched water in a soil comprised of small particulates won't be a problem.

I was under the impression that in addition to avoiding a perched water table, that the mixes were to provide greater aeration to the root zone to enhance root health. Did I misunderstand that? I understand that with the smart pots on the ground, one could use soil, sand, and compost and avoid a pwt, but would this be less ideal than 1:1:1 where there is greater air pockets in the mix?


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Thu, Mar 6, 14 at 17:33

I think more aeration than would be in the example above is still better, eve though in the finer mix a PWT won't be an issue, but we have to weigh how often we want to be tied to watering. As fussy as I am about wanting to be sure plants get a great opportunity to grow to their potential, there are things I'm not willing to do to ensure that opportunity. Watering several times a day a whole bunch of gritty mix filled fabric pots that are in direct contact with soil that wicks & percolates water out and away from the pots is probably one of them. I'd want something that holds onto quite a bit more water.

I'm really glad to see you're able to use the concept in your reasoning. It shows you get it. ;-)

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

Here's the Perlite


 o
RE: Pine Fines

And here's the Pine Fines... (Sorry it's a bit wet.)


 o
RE: Container Soils - Water Movement and Retention XVIII

Reading about wicking, and doing research on 511 and gritty (and what a chore it is to track down the ingredients :) ) had me thinking about "intentional" layering for high moisture-requiring plants.

I started an experiment using a slow draining pot; filling the bottom third with the local clay-based earth, and the top two thirds with commercial patio mix which seems to be about 50% vermiculite if I had to guess. The thought is that; yes the clay holds water but it holds a lot of water before there is any free perched water. so the looser mix is in of itself a wick.

so far the strawberries are doing ok. I water it every 2nd or third day. the setup keeps it nice and damp (not wet).

I might try another pot with the layers reversed for some vietnamese coriander I'm getting ready to pot up.

edit: nevermind, just re-read al's explanation and it seems that the clay will perch water since the air space will be replaced. the reverse layer might be interesting ...

This post was edited by farm96744 on Sat, Mar 8, 14 at 23:12


 o
RE: Container Soils - Water Movement and Retention XVIII

Woodland,

Perlite looks good. Too hard to tell in your bark pic -- need to see it dry and up close -- yours could be too shreddy. That said, strain out all the big chunks over 1/2", as well as the light-colored sapwood, and it will still be much much better than crappy store-bought peat pudding.


 o
RE: Container Soils - Water Movement and Retention XVIII

I was afraid my pic was too dark so I set it out to dry. Much more visible!

Hopefully not too shreddy? The sapwood pieces are really small. How do I get them out? I don't have anything I can see that is larger than a corn flake so I should be ok on size.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by four 9B (near 9a) (My Page) on
    Sat, Mar 8, 14 at 23:20

> Posted by four
> The sum of areas on mulitfaceted stones is more than area of the container floor,
> therefore a coarse layer would not be worse than floor,
> if soil volume remains sufficient for intended plant.
> The advantage is increased evaporation,
> so, I would regard it instead as an evaporation layer.

> Posted by tapla
> Four - I'm sorry - I don't understand what you're saying ......

Ok, to illustrate :


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sun, Mar 9, 14 at 13:20

Farm - FWIW, experiments show that water will perch in layers of material that are comprised of particles smaller than about .100 inch and are layered above particles more than about 2.1X the size of the smaller particles in the over-layer.

Four - Let's say you have a soil that supports 3" of perched water in a 12" deep container. Without the drainage layer, at container capacity, you'll have 3" of soggy soil, then 9" of soil that should support reasonable to very good growth. If you introduce a 3" layer of coarse material on the pot floor, you'll end up with a drainage layer with lots of air porosity that is 3" tall, then 3" of saturated soil, then 6" of soil that should support reasonable to very good growth. Essentially, the drainage layer has cause the location of the soggy soil (perched water) to change to a position higher in the pot, and reduced the depth of soil that should support reasonable to very good growth from 9" to 6". That isn't an advantage because you can roughly duplicate the latter by NOT using a drainage layer and only filling the pot to a depth of 9".

You quoted me in your post upthread, but there isn't enough context there for me to determine what I was discussing, or how it was related to the topic at hand. If you remember where you saw the quote, could you please provide a little more context so I can explain my meaning?

Thanks.

Take care.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

Is my pine fines okay?


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sun, Mar 9, 14 at 14:53

If nothing is lager than a corn flake, it should make a great base for your container medium.

Where do you live?

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

I am in Kentucky Zone 6B


 o
RE: Container Soils - Water Movement and Retention XVIII

Not only are Al's mixes great for mature plants, but they're great for starting seeds as well. I've started seeds in a gritty style of 5-1-1 for the past four years now, and I've never had an issue.

Josh


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by four 9B (near 9a) (My Page) on
    Sun, Mar 9, 14 at 20:51

Josh, do you have to water in a way that avoids the descent of seeds
deeper than they should go for reliable sprouting?


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by four 9B (near 9a) (My Page) on
    Sun, Mar 9, 14 at 21:18

> Posted by four
> if soil volume remains sufficient for intended plant.

> Posted by tapla
> reduced the depth of soil that should support reasonable to very good growth from 9" to 6"

That's cool, we can quantify my "sufficient for intended plant" as being 6".

> Posted by tapla
> what I was discussing... where you saw the quote

The point being made was :
"The coarser the drainage layer, the more detrimental to drainage it is"
It is in episode XVII.

What I have been contending is that the maximum possible coarseness.is that of
the unity (can't call it a part-icle) which is the container floor,


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sun, Mar 9, 14 at 21:27

That doesn't sound like something I would say ("The coarser the drainage layer ....."). I'd still need to see the context.

I'm a little confused, but you shouldn't just say "Alright"!! and be happy because you have 6" of soil above a soggy layer of soil because you believe your plant only needs 6" of productive soil to grow in. You're still going to be dealing with the ill effects of the that soggy layer, the perched water.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

Al - couple questions:

1. If I need X Gallons if 5-1-1, how do I calculate what I Need? I realize that 5 + 1 + 1 does not equal 7 when it comes to volume, because of the smaller particles falling between larger ones. Is there some guide to this?

2. Some, but not all, of my containers will be fabric pots (Smart Pots) sitting on the ground. I realize this will essentially eliminate PWT issues. This is why I am asking question #1. For the fabric pots, since I will have the ground to assist in drainage, what is a good proportion to use if I still want to use the same basic ingredients as the 5-1-1- for simplicity, that will still provide decent aeration and good root growth, but not dry out TOO fast? I was thinking something more like 2-2-1...


 o
RE: Container Soils - Water Movement and Retention XVIII

Greetings.

"Josh, do you have to water in a way that avoids the descent of seeds deeper than they should go for reliable sprouting?"

- I use a spray-bottle to mist the mix before the seeds sprout, and I keep plastic wrap on top. As soon as the seeds show a bit of green, I remove the plastic and begin to water normally with a watering can.

As coarse as the mix looks, there really isn't anywhere for the seeds to go.

Josh


 o
RE: Container Soils - Water Movement and Retention XVIII

That's a good question hair. I wish I had thought of it myself.

When I put together my mix, the pine fines made the bulk of it. I made 3 gallons and it fit a 4 gallon container with a little room to spare.

Of course I still want to hear Al's answer.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Mon, Mar 10, 14 at 15:31

HM4evr - If you use all of a 2 cu ft bag of bark, + 4-5 gallons each of peat and perlite, you'll end up with about 2.5 cu ft of mix, which is not quite 19 liquid gallons (as opposed to the dry gallon, which is calculated as a function of a bushel - 1/8). Actually, that works pretty well as it would yield almost exactly 2 bu ----- if you're not from the city and can envision how much a bushel is. Having worked as a slave on truck farms for most of my youth, I am intimately familiar with bushels and fractions thereof. A dry gallon would be a half peck.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

I realize that 5 + 1 + 1 does not equal 7 when it comes to volume, because of the smaller particles falling between larger ones

I haven't found that there is a significant loss of volume, so don't worry about it. If anything, 5-1-1 has slightly more volume than you start with once it's mixed because there is more air space. One thing many don't realize is that the gallon measurement for typical nursery containers is actually only about 0.7 gallons. I don't know for sure that this is true of Smart Pots, but I have been using them for five years, and they never seem to hold as much as the label says they do.

I use 5 parts pine bark to one part compost to one part NAPA Floor Dry or Turface for my Smart Pots, and it works very well. People who complain that it dries out too fast often have used containers that are too small for the plants they are growing. I wouldn't cut back on the PBF if I were you.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Mon, Mar 10, 14 at 16:02

HM4evr - If you use all of a 2 cu ft bag of bark, + 4-5 gallons each of peat and perlite, you'll end up with about 2.5 cu ft of mix, which is not quite 19 liquid gallons (as opposed to the dry gallon, which is calculated as a function of a bushel - 1/8). Actually, that works pretty well as it would yield almost exactly 2 bu ----- if you're not from the city and can envision how much a bushel is. Having worked as a slave on truck farms for most of my youth, I am intimately familiar with bushels and fractions thereof. A dry gallon would be a half peck.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

Hi Al,

Many thanks for this and your other very informative posts on soils and watering. I was wondering if you could provide a few comments on pot size (large vs. small) and shape (tall vs. broad).

In particular I am interesting in learning more about the perils of overpotting which I have frequently noticed on the forum. Here is a link to an article I recently read on this topic about why using a large pot is not like planting in the ground: "Why the Earth Is Not Like a Pot".

Based on my understanding of your post and this article, I believe that the pot size and shape influence the perched water table. (I think the other author refers to it as a saturated soil column.) However, with a well draining mix, how much of a role does the pot actually play? Could please elaborate on this or correct me if I am wrong.

Many thanks,

Nathan


 o
RE: Container Soils - Water Movement and Retention XVIII

This has come up before, and overpotting isn't really a concern with Gritty and 5-1-1.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Fri, Mar 14, 14 at 18:00

How large a container ‘can’ or ‘should’ be, depends on the relationship between the mass of the plant material you are working with and your choice of soil. We often concern ourselves with "over-potting" (using a container that is too large), but "over-potting" is a term that arises from a lack of a basic understanding about the relationship we will look at, which logically determines appropriate container size.

It's often parroted that you should only move up one container size when "potting-up". The reasoning is, that when potting up to a container more than one size larger, the soil will remain wet too long and cause root rot issues, but it is the size/mass of the plant material you are working with, and the physical properties of the soil you choose that determines both the upper & lower limits of appropriate container size - not a formulaic upward progression of container sizes. In many cases, after root pruning a plant, it may even be appropriate to step down a container size or two, but as you will see, that also depends on the physical properties of the soil you choose. It's not uncommon for me, after a repot/root-pruning to pot in containers as small as 1/5 the size as that which the plant had been growing in prior to the work.

Plants grown in ‘slow’ (slow-draining/water-retentive) soils need to be grown in containers with smaller soil volumes so that the plant can use water quickly, allowing air to return to the soil before root issues beyond impaired root function/metabolism become a limiting factor. We know that the anaerobic (airless) conditions that accompany soggy soils quickly kill fine roots and impair root function/metabolism. We also know smaller soil volumes and the root constriction that accompany them cause plants to both extend branches and gain o/a mass much more slowly - a bane if rapid growth is the goal - a boon if growth restriction and a compact plant are what you have your sights set on.

Conversely, rampant growth can be had by growing in very large containers and in very fast soils where frequent watering and fertilizing is required - so it's not that plants rebel at being potted into very large containers per se, but rather, they rebel at being potted into very large containers with a soil that is too slow and water-retentive. This is a key point.

We know that there is an inverse relationship between soil particle size and the height of the perched water table (PWT) in containers. As particle size increases, the height of the PWT decreases, until at about a particle size of just under 1/8 inch, soils will no longer hold perched water. If there is no perched water, the soil is ALWAYS well aerated, even when the soil is at container capacity (fully saturated).

So, if you aim for a soil (like the gritty mix) composed primarily of particles larger than 1/16", there is no upper limit to container size, other than what you can practically manage. The lower size limit will be determined by the soil volume's ability to allow room for roots to ’run’ and to furnish water enough to sustain the plant between irrigations. Bearing heavily on this ability is the ratio of fine roots to coarse roots. It takes a minimum amount of fine rootage to support the canopy under high water demand. If the container is full of large roots, there may not be room for a sufficient volume of the fine roots that do all the water/nutrient delivery work and the coarse roots, too. You can grow a very large plant in a very small container if the roots have been well managed and the lion's share of the rootage is fine. You can also grow very small plants, even seedlings, in very large containers if the soil is fast (free-draining and well-aerated) enough that the soil holds no, or very little perched water.

I have just offered clear illustration why the oft repeated advice to ‘resist pottting up more than one pot size at a time’, only applies when using heavy, water-retentive soils. Those using well-aerated soils are not bound by the same restrictions. As the ht and volume of the perched water table are reduced, the potential for negative effects associated with over-potting are diminished in a direct relationship with the reduction - up to the point at which the soil holds no (or an insignificant amount) of perched water and over-potting pretty much becomes a non-issue.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

Thank you very much! I was very curious about how all of the properties work together. What was most interesting to me was how the soil volume related to the growth rate. I was surprised to learn that large containers require more frequent watering but it makes sense if there is a fast draining soil. After reading that, I feel some of the problems I have had recently have been due to underwatering. The elimination of the pwt is also why we seldom need to worry about overwatering the gritty mix provided the pot is elevated above the drip tray, correct?

It is great to learn about what is going on inside the soil especially since we can only see what happens outside. Thank you for elaborating on this topic.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Fri, Mar 14, 14 at 19:18

You're welcome. Thanks for the kind words!

Keep learning - it's the fastest way to a green thumb.

"The elimination of the pwt is also why we seldom need to worry about overwatering the gritty mix provided the pot is elevated above the drip tray, correct?" That's right.

Al


 o
Maryartist

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sat, Mar 15, 14 at 13:08

Maryartist. On the off chance you're following this thread - I can't reply to your email message because of how you have your user page settings configured. If you go to your user page and click the box that says, Allow other users to send you email from your profile page or if you wish to receive message reply notifications, and arrange it so the drop down menu just above is configured to "Show your email addy to Members", you're good to go. You'll need to resend your email, email me your addy, post your questions here, or start a new thread. I hope you see this. I get several emails I can't answer every day from GW members, because of how their user page settings are configured.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

Just to be sure I'm understanding:

When you use 5-1-1, in a large container, you can expect rapid growth, larger growth with only the gardener's space and time as the limiting factor.

Should I adjust my understanding of the water requirements on the plant tags at the garden center?

Here is an example of the type of planting I'm expecting:

Arisaema Trifolia as the centerpiece, surrounded by mounding coleus and trailing creeping jenny. I plan to use a large pot, (at least 10 gallons). The water needs of the plants are "medium" according to the standard expectation that you're going to be using peat-based/compost based water retentive soils.

Should I then understand that the watering requirement will be high a planter like this in 5-1-1?


 o
RE: Container Soils - Water Movement and Retention XVIII

Well, 5-1-1 gives you about the best shot out the gate, but it's no guarantee of success. "Rapid and large" growth are relative.

Irrigation in 5-1-1 is more frequent than peat pudding mixes. For the first 3-4 days, you'll want to water daily. Then you taper off to eventually arrive at the final schedule. It's kind of a feel thing. If you have veggies, annuals or roses outside and it's 90 plus degrees, you may need to water daily. If you have a drought tolerant perennial in a cool unheated spot during winter, it might be once a week or longer.

Most people I think water 5-1-1 every 3-5 days, even for "thirsty" plants. The mix holds more water than people think. Remember to keep up with your light but steady liquid fertilizing especially if you don't use CRFs. New plantings in 5-1-1 without nutrients can show signs and go downhill quick in just a few days.


 o
RE: Container Soils - Water Movement and Retention XVIII

Oxboy is right - more frequent waterings after transplant, in order to keep the upper inches of the mix moist while roots are establishing in the new containers.

During the Summer, when the temps are hot, I water my #5 containers every 2 - 4 days on average....which is much less than most folks think the 5-1-1 needs to be watered. This is where that trade-off comes in. *If* you find that you have to water every day, then your chosen container is probably too small for the plant/application - or perhaps you need to shade your container to mitigate excessive heat (sited directly on a hot driveway for example). We also need to remember that one aspect of the 5-1-1 is that larger containers can be used without fear of root-rot, and so it is counter-productive to use such a great mix in a small container. That won't net the results that so many have enjoyed, and will create an inaccurate impression of the mix's performance.

Josh


 o
RE: Container Soils - Water Movement and Retention XVIII

Thank you for your clear answers. I've been growing a very pale green coleus from seeds and I planted seedlings in larger pots that so far haven't needed much watering. So I agree that the idea that you're pouring water through the drainage holes in 5-1-1 is pretty overblown. But I felt the need to ask just in case.

I've watered with a light application of fertilizer and they've done well.


 o
RE: Container Soils - Water Movement and Retention XVIII

"So I agree that the idea that you're pouring water through the drainage holes.."

You want to see niagara falls, try the Gritty mix next. :)


 o
RE: Container Soils - Water Movement and Retention XVIII

Al (or someone else): I may have missed a reply to my question last month in this large thread but should I indeed worry that my gritty mix and/or the pots I'm using seem to be holding a certain amount of water after the initial, almost instant, Niagara Falls when watering? Or is it normal for water to drip a bit when tipping the pots forward?


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Tue, Mar 18, 14 at 17:12

It's normal. Water doesn't perch in pores between particles, at least it shouldn't, but water will perch in the spaces where particles touch, even in soils with very large particles. When you change the vertical axis so gravity tugs in a different direction, some of that water will be pulled loose from in between the particles and exit the drain.

I saw flurry of discussion in my mail, so stopped to see what it was all about. Good advice given by all, which is really great!

Woodlandpatio - if you're going to be watering your immature plantings frequently, you might try using a wick until the roots have colonized the entire soil mass. If/when you see the plants are starting to press you for water more often than you want to be watering, just pull the wick out. Generally speaking though, plantings that require more frequent watering are going to offer plants a greater opportunity to realize their genetic potential than soils that hold onto water for days on end.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

Hey Al, I have a question for you.
In another topic (http://forums2.gardenweb.com/forums/load/contain/msg111319389323.html, November 2, '07), you gave your personal succulent mix. I was wondering why you have silica sand as a separate ingredient from the crushed granite. Aren't they basically the same thing? If they're not the same thing, are they close enough that one can substitute for the other?
Thanks!

Here is a link that might be useful: Succulent Soil Mix


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Tue, Mar 18, 14 at 22:32

Disregard it. For the purpose of a soil fraction, and on a size for size basis, there is not enough difference between them to warrant listing them as separate ingredients. Either could be used and duplication is unnecessary. That was a long time back, but still - sorry for the confusion.

Man! You guys DO read everything! ;-)

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

Thanks for the info!
I've been trying to read, at least. I have a whole google doc 60 pages long that's mostly stuff on container and bonsai soil....
Every time something goes wrong with a plant, I try to figure out what's going on. That means I spend a lot of time reading >_<

This post was edited by AndrewRaz on Wed, Mar 19, 14 at 9:03


 o
RE: Container Soils - Water Movement and Retention XVIII

Thank you again Al for the further explanation on pwt. I was wondering if anyone could also elaborate on root anchorage in the gritty mix especially. I had a little trouble stabilizing the plants after my last repot.

My approach was to withhold water for one week, repot, and begin watering after one more week. The plants are jades and an aloe. Even several weeks after resuming watering, the plants (especially the aloe) still feel loose in the soil. In fact, I ended up putting the jades in 2/3 gritty with 1/3 potting to hold them in better which is something I would prefer to avoid the next time around.

Thanks for any tips!

Nathan


 o
RE: Container Soils - Water Movement and Retention XVIII

Nathan, use stones to hold the succulents in place.
They will anchor very readily in a short amount of time. When you do water, however, be sure to remove the stones so that you don't leave any dry-pockets in the mix.

Josh


 o
RE: Container Soils - Water Movement and Retention XVIII

Thank you everyone for their contributions. I'm in the process of transitioning my balcony container garden to organic for the upcoming season and this weekend's project is preparing the potting mix.

Question about the pine bark. I live in the Pacific Northwest and am wondering if I can replace the pine bark with cedar mulch? To my thinking, it might be less coarse than traditional bark. Here's an example: http://www.homedepot.com/p/COASTAL-2-0-cu-ft-Cedar-Mulch-52058060/100598806

Also, has anyone had success omitting the perlite portion of the 5-1-1 mix?

Happy gardening!


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Wed, Mar 19, 14 at 17:47

Andrew - We usually don't need to look too far to figure out what's wrong with our plants. In most cases, the problem will be linked to poor root health. If you can discount the easy to figure stuff like light and temperature, there isn't much left but root health. Even diseases and insect infestations are seen with much greater rates of incidence in plants with depressed metabolic rates that are caused by problems in the root zone.

I've posted Some Whitcombisms by Dr Carl Whitcomb, Ph.,D, but I'll post them again:

"If the root system ain't happy, ain't no part of the plant happy"

"Roots control the tree, the stems and branches just think [not my emphasis] they are in charge."

"The more roots to share the load, the faster the dirty work gets done"

"Roots provide the fuel for the plant engines we call leaves"

"Each root tip casts a vote to decide what the top will be allowed to do"

"Top growth gets all the glory, but the roots do all the dirty work"

He also notes that "Stress can ALWAYS be measured in the root system before symptoms appear in the top [of the plant]".

*******************************************************************

Jim - I haven't used cedar mulch/bark to grow in, so I can't comment on that practice directly. I can say though, that because the tannins, as well as terpenoid and phenolic compounds cedar is rich in are known to be allelopathic (inhibit growth) to many other plants, I have discounted the likelihood that it would be a suitable choice for me.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Wed, Mar 19, 14 at 18:03

Some plants can be temporarily anchored with these little spring clamps and some garden twine:
 photo repotting027.jpg

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

Agreed. I would not use Cedar mulch.
Use Pine, Fir, Hemlock, and even Spruce (or so I've heard).

Josh


 o
RE: Container Soils - Water Movement and Retention XVIII

Thanks Al and Josh for the replies. Looks like I can pick up Pine mulch at the local big box. I'll call around to the local nurseries as I prefer to shop independents.

I have a confession. I'm finding myself struggling to fully buy in to the 5-1-1 method, or variation thereof, for no good reason. The facts have been laid out clearly and concisely. It's just so different from the typical raised soil/compost beds I've gardened in since I was 5. For containers, I've always used a commercial, peat moss based potting mix, which at least resembles dirt. Even then, those pesky little white perlite pellets annoy the hell out of me. Again, for no good reason; I just think they look tacky because they don't look like dirt. That felt awesome; glad to get that off my chest.

Admittedly, I'm a newcomer to the forum. I know this thread originated somewhere around 2005. Have people documented side by side tests of the 5-1-1 along side other mixes?

My 8 year old daughter is really embracing gardening this year, so I'm thinking about running a test of our own and turning it into a spring/summer project. We're growing heirloom tomatoes (Black Plum and Gold Medal) out of 5 gallon buckets which I think would make perfect test cases. Anyways, I'm off on a tangent. I'll start a new thread if/when we start the test.

Cheers!

Brady


 o
RE: Container Soils - Water Movement and Retention XVIII

For me, container mixes have never looked like dirt, because where I'm from the dirt is a tan color, orange or bright red, and the texture of Play-Doh. It wasn't until I had visited my grandmother's house that I noticed that what she planted her geraniums in was black and fluffy.

If you don't like the look of the perlite (which is understandable) why not cover it with something like leaves, spanish moss, or bark mulch?


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Thu, Mar 20, 14 at 13:51

Brady - If you stick around for a while, you'll have a better idea of why so many are using soil recipes that promise better aeration and drainage, and relief from the excess water retention built into off the shelf soils based on fine particulates. It takes some effort to make your own soils, so it's a sure thing people wouldn't be using it year after year if it was inferior to what's usually commercially available.

The recipes aren't important - just good starting points. What's important is that growers understand what goes on in the root zone of container plantings insofar as water movement and retention and its impact on root health ..... and by extension, plant health.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

Al, if you don't mind, I have a couple more questions on the gritty mix. I asked the first one in the last topic, but I think it got buried in a flurry of rapid-fire responses.

In this topic (http://forums2.gardenweb.com/forums/load/houseplt/msg0410560810570.html) you wrote a bit about your choice of materials in the gritty mix.
You said that the water/nutrient retention of bark is about the average between grit and Turface. So by that logic, bark is not a necessary component where cost and weight aren't a consideration, right? That seems to be the implication, at least.

The second question is kind of similar to the question I asked last week and regards to the exact meaning of the word "sand." I hear that used all over the place, and I wonder if everyone is using it the same way. They say succulents should be in a mix with a good portion of "sand." Cuttings should have "sand" in the mix. Recently, a book I read had a page on rooting large cuttings, and it said to put the cuttings into "coarse sand" to root. Do they all really mean "coarse sand" as basically the equivalent of chicken grit sized grit, or do some of them mean something more fine?


 o
RE: Container Soils - Water Movement and Retention XVIII

Andrew,
coarse sand (the kind that can be used/is recommended for container applications) has a diameter very close to 1/8 of an inch.

Josh


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by four 9B (near 9a) (My Page) on
    Sun, Mar 30, 14 at 15:43

I saw it at Home Depot. No way that I would pay such price.

In my way of thinking, the only valid mineralogical rationale for the name "sand"
would be a silica content much higher than in other stones of high silica content..
Does anyone happen to know whether it is so?


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by four 9B (near 9a) (My Page) on
    Tue, Apr 1, 14 at 2:15

> Posted by AndrewRaz
> by that logic, bark is not a necessary component
> where cost and weight aren't a consideration, right?

Right.
And my gritty is barkless, 1 : 1 .


 o
RE: Container Soils - Water Movement and Retention XVIII

That's a good question: if you're not worried about the cost and weight advantage of using pine fines, could one just use a 1:1 ratio. turface:cherrystone? That way, the soil would last basically forever, since the pine fines is the only ingredient that degrades (on average about 3 years I recall), correct? Curious what Al's take on this would be.


 o
RE: Container Soils - Water Movement and Retention XVIII

Thanks for the answers, they are helpful.

Does anyone use the gritty mix for very large containers indoors? I ask because I have noticed that it drains a lot, and I have to water plants over the sink. I can't imagine doing that with a 24" container filled with gritty mix and a plant. Does anyone use it in containers that large indoors? (I feel like outdoors wouldn't be as much of an issue).


 o
RE: Container Soils - Water Movement and Retention XVIII

Can you carry a 24" container to the sink with any mix in it? For a plant in a container that large to survive indoors, it needs to drain well no matter what mix you use. So you are going to have to make some kind of arrangement to deal with the runoff.

Here's a photo of the largest container I have, an 18-inch ceramic pot that probably weighs at least 30 pounds empty and holds a four foot tall bougainvillea. It has about 16 gallons of gritty mix in it. I needed help to get it into that 2-foot wide drain saucer. I put two bricks in the saucer and rested the pot on top. When I water it, the run off fills the saucer to just below the pot. If there's too much, I use a kitchen baster to remove some of the run off. This plant has been in gritty for a couple years. The plant really thrives in summer. I only need to water it every 2-3 weeks during the winter indoors.


 o
RE: Container Soils - Water Movement and Retention XVIII

24 inches was an exaggeration for the sake of point. It can be done with forklifts, but probably not otherwise unless you have a moving crew. I was just wondering what people do with larger pots that aren't easily movable and a mix that drains freely. You answered that: big basin, and a kitchen baster when necessary. Thanks! :-)
Gorgeous plant, btw!

This post was edited by AndrewRaz on Sun, Apr 6, 14 at 18:56


 o
RE: Container Soils - Water Movement and Retention XVIII

thanks for the detailed info tapla.

can someone give me a quick rundown for the major differences of ideal container succulent mix vs. planting in ground (PIG) mix?

i'm planting in northern california, and up till now i've mixed 1 part soil (low peat) : 2-3 part (pumice, perlite, crushed gravel) with decent results

am i on the right track? (wasn't sure whether i should post this question here or on cacti/succulent sub-forum)


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Fri, Apr 11, 14 at 18:54

Are you looking for recipes for raised beds and/or containers? You'll get a lot of different opinions on the succulent forum about what an appropriate soil might be, and not many will be based on reasoning that centers on what type of root environment will provide the best opportunity for your plants to realize their genetic potential.

Animals and plants are in different kingdoms (Animalia and Plantae kingdoms, respectively) for a number of reasons, one being so we resist attributing animal, and especially human traits to plants. Plants are predictively reactive organisms, and the more you know about plants, the more predictable their reactions will be (for you). Healthy roots are a requirement for healthy plants, but fortunately, a healthy root system isn't difficult to achieve. With some experience, you'll discover that the further you operate outside the concept discussed in this thread, the more difficult it becomes to consistently bring along plants that aren't limited by impaired root health or root function.

Because the variance in opinions will probably leave you confused, in the end you'll probably be better off if you make a decision about whose advice seems to make the most sense from a scientific perspective, and then follow that advice. I would suggest though, that you resist trying to implement everything that sounds like it has the potential to be productive. Much of what you'll read might have that potential, but only under certain circumstances and conditions. First, learn the basics, then start branching out and see what works. I've been growing pretty seriously in containers for about 25 years, experimenting with soils the entire time, and one thing I've learned is that the easiest way to consistently produce healthy plants is by embracing the concept we've been discussing on this thread since '05.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

Okay... why isn't this part of the GW forum that never goes away?


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by neuf 5 Indy (My Page) on
    Mon, Apr 14, 14 at 12:34

Here is a picture of the best that this guy can do with what I have available based on many trips out looking for pine bark fines. It is called a mulch, but is significantly more ground down that "Nuggets".

I hope my Sphagum, Perlite and Vermiculite to five parts pine bark mulch is OK, because I've got some seed planted in it. I am also going to be planting cuttings in the mix.

If I'm screwed, maybe more fine textured mulch will be available somewhere for the next batch.

Thanks!

Jeff

This post was edited by neuf on Mon, Apr 14, 14 at 12:41


 o
RE: Container Soils - Water Movement and Retention XVIII

Your bark doesn't look too bad, but it would be a little better if you could remove the larger pieces by screening it through a 1/2 inch hardware cloth. Why did you add the vermiculite? That's not part of the recipe.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by neuf 5 Indy (My Page) on
    Tue, Apr 15, 14 at 5:41

I added the pine bark and perlite to a mix that was just spahgum peat and vermiculite. The first mix was suggested by a commercial grower for starting seed in another forum at GW and was only a week old when I first found out about 5-1-1. I'll build a screen when I have more time to devote to the soil project. I was not aware of the concept of screening when I first found out about tapla's 5-1-1.


 o
RE: Container Soils - Water Movement and Retention XVIII

I recently got into orchids and African violets, and again realized how much the understanding of the mechanics inspired by this thread gives me a huge advantage over the average beginner to these hobbies. Thank you Al!

My favorite aspect is being able to "over pot" or underpot with impunity, as long as I use the right mix and water/fertilize appropriately. So many times last year I heard how my African violets would die over the winter because I potted them up in too large pots. There were no such comments when I returned this spring with profuse flowers and thick strong roots.

I can grow so many things in a gritty-type mix that are not supposed to survive in Houston - like dittany of crete, which braved a very wet winter like a champ as long as its roots had plenty of air.


 o
Feet First into Gritty Mix

Though I have been educating myself on the site for many, many weeks, this is my first comment. Started my studying back in early January when I received a fantastic Buddha Pine as a holiday gift. The plant was in serious need of a repot. So I purchased some MG and made a meticulous effort to repot this large, beautiful plant.
The deluge and destruction began about 3/4 days later. To my horror I discovered a teeming mass of little tiny flies- this would come to be known as the Fungus Gnat Fiasco! Thank you MG and Scott's.
Over the following days & weeks I spent studying Tapla, Josh, meyermike and many other comments and questions. My quest to find the gritty ingredients began: grit-Tractor Supply, turface-not easy but did find Pro's Choice red @ turf supplier nearby despite the fact it was the dead of winter here in MA. The bark was another story. I went to every possible supplier and touched, inspected, hustled garden supply employees to find the "right stuff". Finally, ended up at Petco (really wanted to find a less costly option). Made my own set of screens and spent hours in the yard sifting and screening in some miserable weather! The fungus gnats were disrupting my life and taking over ALL my plants as each generation continued to hatch despite several attempts to disrupt their life cycle.
So now it's April-3 months later and the transfer is finally complete. All plants in gritty-some with reluctance. Yes, there were mistakes made in my haste to get this all done ASAP. My Meyer Lemon was not happy for a bit but I'm hoping he's finally adjusting. Did file a complaint with MG and got some$$. But the whole process was a huge, crazy mess. Now when I'm at the garden center or a big box store and I see anything MG I cringe.
So this is a shout-out and TVM to everybody in gritty land who unknowingly supported my indoor garden and myself over the past 12-14 weeks of fungus gnat frenzy and gritty mix mania-my friends & family think I'm on a grit & bark bender! Again, without this web I'd probably be plant-less and sad.

This post was edited by darbyndawgs on Wed, Apr 23, 14 at 13:25


 o
RE: Container Soils - Water Movement and Retention XVIII

Forgot to put the thread/subject of posting-newbie error, sorry!


 o
RE: Container Soils - Water Movement and Retention XVIII

Darbyndogs: Welcome, glad you decided to chime in. Congratulations on your long trek and stick-to-itiveness. If you haven't vanquished all the fungus gnats yet, I suggest BT in the form of mosquito bits or dunks or Knockout Gnats. It is the only safe, specific insecticide that is 100% effective against them.


 o
RE: Container Soils - Water Movement and Retention XVIII

Ohiofem: Thanks so much for the welcome. I tried everything-there's a hydroponic store nearby and I went through sticky traps, DE, BTI, safe spray and repots until I did the gritty! Those gnats are pesky devils and they are like unwelcome relatives-they kept coming back. But I hopefully have had my final throw down thanks to gritty. BTW- fungus gnats are a common problem with MG guess I was lucky in the past. Never going back though.


 o
RE: Container Soils - Water Movement and Retention XVIII

I had some MG I used as the peat component in 5-1-1 and it was nothing but gnats. Disgusting. Threw it out and I'm not buying from them again. Bleh.


 o
RE: Container Soils - Water Movement and Retention XVIII

I've got a question about the pine bark--I could not find anything in the right size range except cedar. What kind of problems with the soil might having "mini" nugget sized wood chips cause? Are there ways to compensate for this either in mixing the soils or when fertilizing? (the recommended ways of breaking them down: lawnmower, car wont work as I don't have those tools, nor do I have the space for composting).
(I'm looking at the 5:1:1 mix--though I think I'm a bit low on perlite as well)

This post was edited by silverrowan on Sat, Apr 26, 14 at 16:47


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Sat, Apr 26, 14 at 12:50

To those asking about omitting bark from Al's recipe, what you are basically talking about is a Missouri Gravel Bed mix being researched at the U. Of Missouri. They recommend no more than 40% turface. I use 2:1 gravel:turface and it works pretty well. I am thinking about getting a half yard of 1/4" scoria for a little better water retention though since I'm in SoCal.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by four 9B (near 9a) (My Page) on
    Sat, Apr 26, 14 at 22:59

> Posted by nil13
> > I use 2:1 gravel:turface
>`
> thinking about getting a half yard of 1/4" scoria for a little better water retention

I am guessing that price of Turface is the driving consideration
both in your current ratio, and in the scoria idea.
Is scoria close in price to bark?

This post was edited by four on Sat, Apr 26, 14 at 23:39


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sun, Apr 27, 14 at 21:55

I've been away for a while - out to the East Coast for a bonsai convention. It was a great time - a LONG drive, though.

Nil - if the scoria is available screened to your specs, opt for something finer. .100-.125 would be perfect, with maybe a small; fraction of the whole a little larger than .125 if it can't be helped.

SR - I wouldn't use cedar or any sort of sapwood, though redwood in an appropriate size range might be ok.

Al


 o
acceptable diameters

  • Posted by four 9B (near 9a) (My Page) on
    Mon, Apr 28, 14 at 21:15

Hi, Al. Would you say that the upper tolerance in size is more flexible for bark than for stony components?
.


 o
RE: Container Soils - Water Movement and Retention XVIII

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Mon, Apr 28, 14 at 21:48

Only because the bark tends to break down and get smaller with time. If it didn't, then the "ideal" bark size would be the same as the ideal inorganic particle size - in that 1/10 - 1/8" size range.

Al


 o
RE: Container Soils - Water Movement and Retention XVIII

sorry, it's probably answered in the long Q&A, but are the fertilising options for the mix down to:

1. CRF only and nothing else, or
2. No CRF/fertilising weakly with using a water-soluble fert. and adding Ca or Mg if it's not present.


 o
RE: Container Soils - Water Movement and Retention XVIII

You can use both CRF and soluble fertilizers in conjunction - that's how most of us do it :-)

Josh


 o
RE: Container Soils - Water Movement and Retention XVIII

oh. the reason I put it that way is because I have a soluble fert. that has everything apart from Mg. So, if I add that, there's no reason for the CRF. Is CRF mainly just a convenience thing for those that don't want to water with fertiliser every time?


 o Post a Follow-Up

Please Note: This thread has reached the upper limit for the number follow-ups allowed (150). If you would like to continue this discussion, please begin a new thread using the form on the main forum page.


Return to the Container Gardening Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.


Learn more about in-text links on this page here