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Container Soils - Water Movement & Retention VI

I first posted this thread back in March of 05. Five times it has reached the maximum number of posts to a single thread (150), which is much more attention than I ever imagined it would garner. I have reposted it, in no small part, because it has been 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 hopefully, the exchanges provide helpful information. Most of the motivation for posting this thread again comes from the participants reinforcement of the idea that some of the information provided in good-spirited collective exchange will make some degree of difference in the level of satisfaction of many readers growing experience.

I'll provide links to the previous five threads at the end of what I have written - in case you have interest in reviewing them. Thank you for taking the time to look into this subject - I hope that any/all who read it take at least something interesting and helpful from it. I know it's long, but I hope you find it worth the read.

Al

Container Soils - Water Movement and Retention - A Discussion About Soilssize>

As container gardeners, our first priority should be to insure 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. 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 IÂll 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 as an 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.

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 Water Movement information.

Consider this if you will:

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 enough nutrients in available form to sustain plant systems. Gas Exchange - It must be sufficiently porous to allow air to move through the root system and by-product gasses to escape. Water - It must retain water enough in liquid and/or vapor form to sustain plants between waterings. 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 of water in 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, waterÂs bond to itself can be stronger than the bond to the object it might be in contact with; in this condition it forms a drop. 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 .125 (1/8) inch.. This is water that occupies a layer of soil that is always 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 perched. The smaller the size of the particles in a soil, the greater the height of the PWT. This water can be tightly held in heavy (comprised of small particles) soils and Âperch (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, and 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. 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: 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 drain better. 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?

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 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 starve/"suffocate" because there is insufficient air at the root zone to insure normal water/nutrient uptake and root function.

Bark fines of fir, hemlock or pine, 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 natureÂs 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.

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 havenÂt 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 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 ½ BB size I leave it out of soils. Compost is too unstable for me to consider using in soils. The small amount of micro-nutrients it supplies can easily be delivered by one or more of a number of chemical or organic sources.

My Basic Soils

5 parts pine bark fines

1 part sphagnum peat (not reed or sedge peat please)

1-2 parts perlite

garden lime (or gypsum in some cases)

controlled release fertilizer (if preferred)

micro-nutrient powder, other continued source of micro-nutrients, or fertilizer with all nutrients - including minors

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)

1/2 cup micro-nutrient powder (or other source of the minors)

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)

micro-nutrient powder (or other source of the minors)

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 vigor closer to their genetic potential. 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, pea stone, coarse sand (see above - usually no smaller than ½ BB size in containers, please), Haydite, lava rock (pumice), Turface or Schultz soil conditioner, and others.

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

1 part uncomposted pine or fir bark

1 part Turface

1 part crushed granite

1 Tbsp gypsum per gallon of soil

CRF (if desired)

Source of micro-nutrients or use a fertilizer that contains all essentials

I use 1/8 -1/4 tsp Epsom salts per gallon of fertilizer solution when I fertilize (check your fertilizer - if it is soluble, it is probable it does not contain Ca or Mg.

Thank you for your interest.

If there is additional interest, please find previous postings here:

Posting V

Posting IV

Posting III

Posting II

Posting I

Al

Comments (152)

  • tapla (mid-Michigan, USDA z5b-6a)
    Original Author
    15 years ago
    last modified: 9 years ago

    Why not approach this from a volume perspective? The basic recipe is based on volume & not weight. 8-1/3 gallons each, of pine bark, Turface, and granite. If you want to adjust, keep the organic component at 1/3 or less and the inorganic component at 2/3 o/a - adjust the inorganic components as req'd. It makes life easier. ;o)
    E.g.
    3 parts bark
    4 parts Turface
    2 parts granite
    yields a 2/3 inorganic:1/3 organic soil.

    Don't incorporate the Epsom salts - it should be an ongoing thing, mixed with fertilizer solution (unless your fertilizer contains Mg - most don't) @ 1/4 tsp per gallon whenever you fertilize. Uncomposted, small chunks of pine bark with few (or no) fines are best in the gritty mix.

    Here's another current discussion with a picture of the soil:


    Al

  • aliceinvirginia
    15 years ago
    last modified: 9 years ago

    I went to the more convenient large nursery near me (Merrifield's), and bought something called Superfines. Don't know if it is a product just of that nursery.

    How can I tell if it is the right stuff, or if it contains shredded hardwood as well, or if it is composted?

    pH tests? I remember something about a perched water test, but I don't remember if that was for this or for the Turface.

    I haven't opened the bag yet. The nursery said the sample bins have been sitting there a long time, so don't necessarily match the bag contents. The sample bin looked the size of the particles at 12 o'clock but was the color of 3 and 9.

    Last year I turned up my nose at the Virginia Fines like the ones at 3 o'clock. I couldn't see what was in another bag, so I ended up buying something slightly larger from another nursery.

    I should probably just have gone back to the nursery that told me that their soil conditioner was the right stuff, and where it looked like the one at the top. But it was considerably further away (Wolf Trap Nursery). I figured I'd give the names of the nurseries for other people in the DC/northern Virginia area.

    Thanks,
    Alice

  • tapla (mid-Michigan, USDA z5b-6a)
    Original Author
    15 years ago
    last modified: 9 years ago

    How can I tell if it is the right stuff, or if it contains shredded hardwood as well, or if it is composted?

    I don't know, Alice. Ask - read what it says on the bag - call the company that packages the product, smell it (piney odor), examine it to see if the bark particles are pine .....

    Forget the pH tests. The PWT test was just a check to see if the soil held perched water. If you think your product is pine bark, if you follow the recipe, you should be fine, but you can do the PWT test if you're curious. Of course, my goal in providing the info here was so you could understand how 'it all goes together', but if you hang around a while, you'll eventually absorb most of it by osmosis. ;o)

    Al

  • lilion
    15 years ago
    last modified: 9 years ago

    Gosh, I hate to ask even more questions, but I really do want to make my own potting mix this year. I've finally found a nursery where I can buy fine pine bark mulch. It doesn't seem to be composted really, but it is what the nurseryman tells me they make their own potting mix out of...along with peat and sand. I told him about Al's mix and that it was pine bark fines, peat, perlite and lime. He said they never use lime and it isn't necessary. I'd think, since I might be buying it from him, he'd have sung its praises, but who knows?

    So...why is lime necessary? Is it because the pine is acidic?

    And...If the mix is 5 parts pine bark, 1 part peat and 1 part perlite - how much lime? I don't seem to see the amount anywhere, although I may have missed it.

    And...is hydrated lime okay? I have a bag of that for lowering ph in the garden.

    Thanks!!!

  • lilion
    15 years ago
    last modified: 9 years ago

    Didn't Al's mix used to have controlled release fertilizer back when it was like 3-1-1? Maybe it was someone elses mix I saw here...but don't you need some long-release fertilizer?

  • tapla (mid-Michigan, USDA z5b-6a)
    Original Author
    15 years ago
    last modified: 9 years ago

    Hi, Alys. Any soil with bark and peat as the two primary components is going to be very low in Ca and Mg, and low in pH (4.5 and lower is not uncommon). Since we need to supply Ca and Mg, as well as raise pH, and dolomitic limestone does all three, it is the most preferred method of accomplishing these things. I'm not sure why your nursery person told you lime is not needed ..... well, I guess technically it isn't - you could jump through a dozen technical hoops to accomplish your goals, but it's pretty silly to do so with something as simple as dolomite at the ready. I think I would have quickly engaged him in conversation by asking him how he raises pH and how he gets Ca and Mg to the plants. I'm sure his answer would have immediately revealed whether or not you were talking to the right guy. ;o)

    Your hydrated lime (calcium hydroxide) is another material which may be used for a rapid reduction of pH. However, this material contributes more ions to the soluble salt content of the media than ground limestone, and lacks Mg, setting you up for a possible Ca induced deficiency (antagonistic deficiency) of Mg. Generally speaking, the amount of hydrated lime used is reduced by 1/3-1/2 of the quantity of ground limestone used, but I wouldn't suggest using it.

    As noted, the most preferred material for raising pH is dolomitic lime (a calcium/magnesium carbonate). This material reacts much the same as calcium carbonate but also supplies magnesium for plant growth. This is particularly important where magnesium is not included in the liquid or granular fertilization programs.

    The actual amount of these materials to use per cubic yard of growing media is based on the CCE, cation exchange capacity and existing pH of the media, non of which any (?) of us measure. Since most of these values are not available for our soilless growing media, it is virtually impossible to precisely calculate how much material to add to achieve a desired pH. Generally speaking, growers use between 3-7 pounds of dolomitic lime/cubic yard of media to adequately buffer pH. However, the only way to be absolutely sure is through a trial and error procedure, but none (?) of us check, so we take an educated guess. I have been very happy adding 1 level tbsp dolomitic (garden) lime per gallon of the 5:1:1 mix or 1/2 cup/cu ft.

    Al


  • justaguy2
    15 years ago
    last modified: 9 years ago

    Alys,

    In the first post in this thread controlled release fertilizer is listed. It isn't necessary, but convenient for those who don't always keep on top of fertilizing.

    The lime question is answered by the trade in general. Virtually every bag of commercially produced bark or peat based potting mix is limed by the manufacturer. Why this nursery doesn't or what they do about pH I have no idea. Al also explains why the lime is necessary.

    Within this thread the issue of 'why lime' is answered in detail.

  • lilion
    15 years ago
    last modified: 9 years ago

    Thank you both very much. I thought I'd read this whole thread...and a couple more of them; I believe this particular thread has had several reincarnations...but I guess I missed the lime part.

    Thanks especially to Al. I'll definately remember to get some dolomitic lime.

  • happygardener23
    15 years ago
    last modified: 9 years ago

    I'm de-lurking and showing my incredible ignorance all for the love of tomatoes!

    Ok, I've looked over all of the earlier threads and am humbled by how much you all know and how much I can only hope to someday learn. Since you're leaps and bounds beyond me, maybe you can chime in so that my tomatoes don't suffer from my learning curve.

    So, I'm looking to have a container garden for fruiting plants (tomatoes, cucumbers, beans, peas, strawberries, etc.) I'll be growing in plastic pots. Nothing fancy or anything that requires power tools or 7 trips to the hardware store to construct. The pots will be on my brick patio. I am not open to using harmful chemical fertilizers. I'd rather forego the home garden entirely than do that (sorry).

    Now my questions....what growing medium mix should I be using? I know there's the basic recipe above, but somewhere along the threads I seem to recall reading that for veggies it's best to just use 5 parts pine bark fines and 1 part peat. Is that right? I also understand (I think?) that I should be using some sort of wick to allow the drainage of "trapped" water and that since I have a brick patio, the pots can just sit directly on the patio with the wick trailing out of the pot and onto the brick (but I don't know what makes a good wick vs. a bad wick or if there's any special way to position the wick within the pot). I also have been winter sowing my seeds in a homemade potting mix of 2 pts. mushroom compost, 2 pts. peat, and 1 pt. vermiculite. How do I handle the transfer of my sprouted seeds from this medium to the preferred mix in larger containers when the time comes?

    I totally don't understand fertilization or all of the wonderful nutrients and nutrient delivery agents that you have all discussed in such impressive detail. I need major guidance in this area.

    Can I just have the "for Dummies" version? I just need to be told exactly what to buy (I have HD, Lowes, Meijer, Ace, etc. available to me and I'm not opposed to looking elsewhere or buying online if I know what I'm looking for). I need to know what proportions to mix, what exactly to add, how to marry pot to container to wicking system in harmony, and how to fertilize (when, with what, how much). I need it to be explained to me as if I have NO IDEA what I'm doing or how gardening works, as I'm starting to discover how much that is the case.

    I promise that I will do what I am told and think of you all every time my girls stuff their faces with veggies fresh from the vine (I can hardly imagine how amazing my harvest will be this year now that I'm realizing how much I've been doing wrong in prior years).

    Thank you in advance, and thank you especially to Al for your amazing body of knowledge and your equally astounding desire to impart it to others to make the world a happier, greener place.

  • justaguy2
    15 years ago
    last modified: 9 years ago

    I am not open to using harmful chemical fertilizers. I'd rather forego the home garden entirely than do that (sorry).

    To put it nicely calling inorganic, water soluble nutrients, the only nutrients plants can use 'harmful chemicals' is silly. It reflects a basic misunderstanding.

    Using organic matter results in soil life processing the organic matter which results in inorganic, water soluble nutrients. Using water soluble, inorganic nutrients from the get go bypasses the soil life which is desirable in a container where that soil life doesn't thrive.

    There is nothing harmful about it.

    I will leave your other questions to others or to your rereading the thread, I just chimed in due to my frustration with organic minded growers (of whom I am one) calling synthetic fertilizers "harmful chemicals" when they are simply essential plant nutrients in a form plants can use right now without waiting for 'soil life' to work on them.

    What works well in the soil works well because of the soil. There is no soil in containers and if there were one would have major drainage/aeration issues.

    You need to change your mindset. Containers aren't the earth nor are they filled with them. Different rules apply.

  • tapla (mid-Michigan, USDA z5b-6a)
    Original Author
    15 years ago
    last modified: 9 years ago

    "what growing medium mix should I be using?"

    As you might easily guess, I would steer you toward a minor variation of the mix you described & have you add 1 part perlite to the mix.

    Wicks you use for drainage needn't be as absorbent as those you use to pull water up into the container for irrigation purposes, but I've found that strips from 100% rayon mop heads, or strips cut from 100% rayon (man made chamois) are great. The wick should be secure in the soil and contact the soil at the lowest part of the container. It doesn't matter if it is in the middle & more is not better.

    I'm surprised that you have had good results with the shroom compost, peat, vermiculite mix (have you?) because of it's likely high salt content & extreme water retention. Handle the transfer to this mix as you would to any other. Try to keep roots as intact as possible & keep the media moist and humidity high until the seedlings have established.

    Fertilizer: I'm not being harsh or on a high horse - just frank when I say I'm not going to tell you what to buy unless you relent on the all-organic approach. It's not that I'm trying to beat-up on you for being organic minded - not at all; it's just that I have no idea how to advise you to proceed with an organic agenda that will deliver the effort:reward quotient that soluble fertilizers will offer in containers. I've tried the organic approach, and though I adhere tightly to it in the gardens/beds, I find it very troublesome, & frankly, much less productive in containers. I'll have to leave you to your research on this subject. If you want guidance as to what soluble fertilizers are appropriate, please ask and I (or someone else) will be happy to help. ;o)

    Thank you too, for your kind words and the thank-you. I really appreciate it. ;o)

    Al

  • happygardener23
    15 years ago
    last modified: 9 years ago

    To be clear, I was using the term "harmful" as a qualifier. I can only assume (forgive my ignorance) that there may be some fertilizers that are not 100% pure organic matter that have been deemed to be essentially harmless (aka not harmful) due to the way that they are or are not processed by the plant vs. other applications that may in fact be harmful or potentially more harmful than others particularly when the plant, or portions of the plant, will ultimately be consumed by young children.

    I am not educated enough to speak to what these more, less, or non-harmful non-organic fertilizers might be, and I was hoping that some of you are. I was merely trying to distinguish my priorities and clarify that am willing to compromise some degree of productivity and appearance in my fruit to avoid harmful chemicals (harmful ones, not necessarily ALL of them-unless they're all harmful but you seem to suggest that it not the case, so I assume that you can advise me on which ones to use) being applied to what will be an edible plant.

    With regard to the planting medium. It looks like the recommendation is 5 pt. pine bark fines that are smallish (as pictured in the examples-likely to be found at HD, Lowes, or Meijer-labeled "pine bark fines" or mulch?) 1 pt. peat (already have) and 1 pt. perlite (I'll order online). Sound right?

    Thanks again!

  • happygardener23
    15 years ago
    last modified: 9 years ago

    Oh, and I forgot to say that I'm not married to any particular mix for WSing the seeds. If you have a better suggestion, I'm all ears (and have many seeds yet to sow). I just used the mix recommended on the WSing board.

  • tapla (mid-Michigan, USDA z5b-6a)
    Original Author
    15 years ago
    last modified: 9 years ago

    Sounds like you have the mix right, HG. Don't forget the lime, though.

    If I was starting seeds, I would go to the NAPA car parts store & buy a $7.50 bag of Floor-Dry. I would mix it with sphagnum peat at 5 parts Floor-Dry: 1 part peat and use no fertilizer until the first set of true leaves starts to emerge - then a 1/4 recommended strength dose each week until planting time.

    Ideally, a fertilizer with a 2:1:2 or a 1:1:2 ratio that has all the nutrients (or include a micronutrient (MN)supplement) would be best. Alternately, any 1:1:1 fertilizer (with MNs or a MN supplement) supplemented with a little 0-0-3 ProTeKt (a potassium supplement that also contains silicon) would really help to strengthen the seedlings.

    Al

  • justaguy2
    15 years ago
    last modified: 9 years ago

    I am not educated enough to speak to what these more, less, or non-harmful non-organic fertilizers might be, and I was hoping that some of you are. I was merely trying to distinguish my priorities and clarify that am willing to compromise some degree of productivity and appearance in my fruit to avoid harmful chemicals (harmful ones, not necessarily ALL of them-unless they're all harmful but you seem to suggest that it not the case, so I assume that you can advise me on which ones to use) being applied to what will be an edible plant.

    None of the synthetic fertilizers are harmful to humans unless one eats it directly. They are just nutrients. Think vitamins. Miracle Grow, Foliage Pro, Dynamite, Schultz etc. are all fine to use.

    Plants use inorganic, water soluble nutrients. Those nutrients can be contained in organic matter and released over time by soil critters (largely absent in a container) or they can be prepackaged in water soluble, inorganic form so the plants can use them right away.

    There is nothing at all harmful about using them on plants kids will eat. My own kids eat them. Virtually every produce item you buy at the store or eat at a restaurant was grown using synthetic fertilizers.

    I can understand being concerned about pesticides, but not plant nutrients.

  • jodik_gw
    15 years ago
    last modified: 9 years ago

    This thread deserves to be bumped... with spring just around the corner, it can be very useful to many gardeners!

    I'm tellin' ya, Al... you should include this and your other article about fertilizers in a book! I'd stand in line for hours just to buy a copy and have you sign it! ;-)

  • deep_roots
    15 years ago
    last modified: 9 years ago

    Root crops (potatoes, onions, radishes, yams, etc.), with all the container gardening talk, I would like to try growing some more vegetables in containers this year. While the container mixes that Al suggests seem great for most plants, does anyone have any ideas for modifying the mix for root crops or experience proving the mix is useful in these applications as well?

  • justaguy2
    15 years ago
    last modified: 9 years ago

    Onions aren't root crops ;) They are actually better thought of as a leafy crop, like lettuce is.

    Anyway, why would a mix suitable for growing veggies and flowery stuff *not* work for potatos, onions and radish?

    I don't really grow potatos, but I have grown onions and radish in mixes similar to Al's 5-1-1 mix and it works just fine. There really isn't anything special about the mix other than it provides better than average aeration to the roots while holding on to a reasonable amount of water.

    That is a recipe for success with any plant regardless which part of the plant we want to eat.

  • deep_roots
    15 years ago
    last modified: 9 years ago

    Provided I water and fertilize properly, I would like to experiment with the gritty mix. With vegetables like potatoes and yams, I was concerned the weight of the mix would not expand as well as a fluffy peat-based mix.

    Also, I appreciate your feedback on radishes and onions doing well in a modified 5-1-1 mix. I would like my container vegetables to have at least the same vigor as when grown in my raised beds. In looking at onions growing from another thread, I am wondering if the larger tote-style containers would do better with exceptional drainage and aeration.

    {{gwi:1235}}

    It seems that field grown vegetables get larger and display more health in general.
    {{gwi:1236}}

  • justaguy2
    15 years ago
    last modified: 9 years ago

    With vegetables like potatoes and yams, I was concerned the weight of the mix would not expand as well as a fluffy peat-based mix.

    Well, think of it this way. Would it's weight be greater or lesser than the typical garden/field soil folks grow them in?

    I am curious though as to why you would choose the gritty mix over the 5-1-1 mix for veggies.

    I am not going to suggest it won't work well (never tried it), but it seems... unusual to build a long lasting mix for a short term plant. Is the idea to reuse it pretty much forever? It seems that field grown vegetables get larger and display more health in general

    I used to frequently hear/read folks saying it was unreasonable to expect container grown plants to do as well as ground grown plants. I never understood that. If we are 100% meeting the plant's requirements for optimal growth, what difference would growing in a container make versus in ground?

    In a container we have more control over nutrients, moisture levels and with an appropriate potting mix, aeration.

    About the only limiting factors I can think of are potting mix volume and lack of temperature insulation.

  • deep_roots
    15 years ago
    last modified: 9 years ago

    justaguy2,
    Yes, I was considering the gritty mix for a long-term use with short-term plants. At end of season, I was considering a hydrogen peroxide or bleach solution, followed by an adequate rinse. This would be for 22" diameter pots that would be left out over winter and re-used in spring. I was considering periodic fertilizing with slow-release Osmocote and occasional watering with Maxi-Crop sea kelp solution. Watering would be done with drip irrigation.

    You mention container volume and temperature buffering, both of which are good points. I try for larger containers, but am looking at ways to control temperature spikes in late summer.

    If I can fine tune the process, I may end up doing more vegetable gardening in containers.

  • deep_roots
    15 years ago
    last modified: 9 years ago

    Just a thought, but anyone changed out a 35 gallon potted 8' high palm for gritty mix over a nice carpet?

    I am thinking two guys to pull out the plant after tipping it over onto newspapers; a garbage can for manually removing and discarding old container mix; and backfilling with gritty mix.

    It's my fault that the plant won't fit out the door and is too heavy to get to the elevator.

  • deep_roots
    15 years ago
    last modified: 9 years ago

    One time, Al mentioned getting Axis and PlayBall in Indiana. Anyone know where that was? Also, aside from the weight, what would you think of planting in pea gravel for long term plantings?

  • azbookworm
    15 years ago
    last modified: 9 years ago

    New to Northern Virginia. Looking for Turface. Anyone know where I can get it without purchasing a 50 lb bag? I want to try this "Al's Mix" on some of my houseplants. Try. Not ready to commit.

    BTW - great work by Al, Justaguy2, and others. Thanks for all your time and patience with us Newbies!!

    Mary

  • justaguy2
    15 years ago
    last modified: 9 years ago

    Mary, See if any of the garden centers around you carry Schultz Soil conditioner in 5lb bags. It's Turface inside, at a premium per pound price. Don't be confused by other products called 'Soil Conditioner' that are bark/wood products, Turface looks more like clay kitty litter and will be the Schultz brand. I believe there are some other sources of it in 5lb bags, but can't recall names.

  • tapla (mid-Michigan, USDA z5b-6a)
    Original Author
    15 years ago
    last modified: 9 years ago

    It was in Indianapolis, but I don't remember the place I bought it now. That was more than 10 years ago.

    Peastone doesn't work well because of its wide variance in size. When I talk to groups about soils/container gardening, I use a clear plastic canister filled with a quart of boulder-size marbles. I point out the wonderful aeration the space between the marbles offers. I say "This canister is completely full of marbles ..... can't get any more in it - right?" Then I add a pint of BBs to the quart. So now I have 1-1/2 quarts in a 1 quart container. Finally, I add another pint of fine sand, so I've put 2 quarts in a 1 quart container, destroying that wonderful aeration in the process. That is peastone.

    I suppose if you wanted to screen out everything that passes through insect screen and what's left on top of 1/8 or 3/16 hardware cloth (depending on the application) you could use it; but if you're going to do THAT ..... crushed granite is prescreened, and for what volume of peastone you'll have left after screening - less expensive and no work. Not a difficult decision, for me. ;o)

    Al

  • azbookworm
    15 years ago
    last modified: 9 years ago

    Thanks Justaguy2,
    I checked Schultz - they no longer package the soil conditioner. I am looking into the kitty litter route or the aquatic soil route. I have looked at local nurseries and hardware stores with no success. Maybe it is too early in the "growing season" here.

    Thanks for your help.

  • lilion
    15 years ago
    last modified: 9 years ago

    Well I'm committed to using Al's mix this year, and it looks like I'm going to have a LOT of it! The only thing I'm having trouble finding is the lime for some reason. Hydrated lime is everywhere, dolomite, not so much. Found the bark for $40 a "scoop" - they don't sell lesser quantities. Peat and perlite I can find at Lowe's. For the gritty mix I found both granite grit and turface for $8 for a 50 lb bag. Again, can't buy less. I'm not sure how big a 50 lb bag is, but judging by the 40 lb bags of dogfood I buy - it's a LOT.

    I have two large (4' x 18") planters that I think I'll use the gritty mix in even though I plant petunias and cucumbers in them, since I hate the thought of emptying them every year because of the size. Other than that, I don't actually have many perennials. I was wondering, what would it do if I used the turface in place of the perlite in the regular mix? If it doesn't hurt anything, would I need to change anything else?

    I'm getting excited about spring!

  • justaguy2
    15 years ago
    last modified: 9 years ago

    Alys,

    If you use Turface in place of Perlite (something I do often) you have a heavier container and the Turface will hold more water than perlite.

    In my 5 gallon bucket test, Turface will hold a larger volume of water than small sized, uncomposted bark fines will.

    AZ,

    If you use kitty litter or Oil-Dry or other Turface replacements be sure to soak a sample in a cup of water overnight and check it in the morning. Some folks get lucky and find it stays solid, others, like me, find it turn to clay muck. It seems that those who find a suitable replacement have it remain suitable from bag to bag and those who don't find them suitable also have a consistent experience from bag to bag. Seems to be a regional manufacturing thing.

    Also, thanks for the info on Schultz, I didn't realize they stopped offering it.

  • lilion
    15 years ago
    last modified: 9 years ago

    Holding more water doesn't sound like much of a problem. I just wouldn't have to water as often, right? Or did I miss something? I seem to do that reading all this material.

  • justaguy2
    15 years ago
    last modified: 9 years ago

    Using Turface in place of perlite would extend the interval between necessary waterings a bit, yes. It's one of the reasons I use it in place of perlite myself (it's also why I use large containers for anything that pouts quickly if the moisture levels are on the dry side of moist).

    If you use a fast draining mix that maintains no PWT (or maintains an inconsequential PWT given root depth/container height) you are freed to water as often as you like (because air spaces are being maintained), but by choosing the amount of water each ingredient can hold on to you can extend the interval at which watering becomes a necessity.

    Frequent waterings are still helpful to bring in fresh oxygen and push potentially harmful gasses out before they become a problem.

  • lilion
    15 years ago
    last modified: 9 years ago

    Sounds good. I have a week in the height of summer I'm always out of town and I hate the idea of having to get a friend or neighbor to water several times so if I can water less often that'll do. I think I'll still buy the perlite and use it in containers where weight is a question, but if I have a ton of turface left over after doing the perennials, I'll likely incorporate that into my bigger pots. Thanks!

  • aliceinvirginia
    15 years ago
    last modified: 9 years ago

    Mary - if you find a source of Turface in NoVA let me know. I'm thinking of going that route too.

    Also, I did some research on the Norfleet Superfines.

    They are composted, but they are half hardwood bark and half pine bark.

    Norfleet also sells Virginia Fines Special Blend which is all pine fines.

    Thanks,
    Alice

  • lilion
    15 years ago
    last modified: 9 years ago

    Husband picked up the turface and granite today since those stores close before I get off work. In thinking I'd have really big bags, I wasn't thinking about the fact that granite is a ROCK! Duh. So...not as much as I thought. Is there any substitute for the granite so I don't have to buy a bunch more?

  • tapla (mid-Michigan, USDA z5b-6a)
    Original Author
    15 years ago
    last modified: 9 years ago

    It really boils down to being mainly about size. I use the granite because the size is so close to perfect. It's purpose in the soil is to add to the bulk of the soil, contribute to macro-porosity (big air pores), and help reduce water retention. Other substitutes would be lava rock (pumice) in the same size, Haydite in the same size, or perlite. Perlite is very light and plants that don't tolerate fluoride well might not like a soil with a 1/3 perlite component.

    Al

  • filix
    15 years ago
    last modified: 9 years ago

    I wanted to try sifting some of my bark through a few different size screens and record the results. I have alot of bark ready to be used that I sifted through 1/4 inch screen. There is alot of fine stuff in there. I want to sift some through a insect screen to get the real fine bark out and use the top stuff. Also some through a 1/8 screen and use the stuff that stays on top. Then some of the bark that went through the 1/8 screen, resift that through an insect screen and use that stuff.Then finaly use the bark that passed through the 1/4 screen without doing more to except add more perlite then the others. And see how the same plants do, filix

  • tapla (mid-Michigan, USDA z5b-6a)
    Original Author
    15 years ago
    last modified: 9 years ago

    Ok. ;o) Keep us posted.

    Al

  • filix
    15 years ago
    last modified: 9 years ago

    Al I'm sure you already know what the outcome will be. Am I waisting my time? :>) filix.

  • justaguy2
    15 years ago
    last modified: 9 years ago

    Am I waisting my time?

    Not if you are having fun :)

  • justaguy2
    15 years ago
    last modified: 9 years ago

    I have been going through my bookmarks lately, cleaning house so to speak. In the process I have come upon a few old gems.

    One that I wanted to share with everyone with an interest in this thread is this one.

    It's an article from Ohio State university on physical characteristics of growing media. The reason I am putting it in this thread is because as I reread through it I had to chuckle at how similar the author sounded to Al. I had to check to see who the author was to make sure it wasn't Al :)

    In many ways this article says the same thing Al does, but in a little different way, but they both still sound quite alike. See what you think.

  • tapla (mid-Michigan, USDA z5b-6a)
    Original Author
    15 years ago
    last modified: 9 years ago

    "Al I'm sure you already know what the outcome will be. Am I waisting my time?"

    I have a pretty good idea, but your actually seeing the results will give you a better feel/understanding, and additional confidence when you make future soil decisions. No matter how it turns out, it won't be wasted effort - experience is a good teacher. It's the same kind of thing I used to do while the whole 'soil thing' was coming together in my mind.

    Al

  • filix
    15 years ago
    last modified: 9 years ago

    Thanks Al. I'm thinking the bark that goes through a 1/4 inch but won't go through an 1/8 inch might be the best. Because it will be very fast. Just more work to keep wet.
    justa, cool link. Does sound alot like Al. Good science is good science. filix

  • tapla (mid-Michigan, USDA z5b-6a)
    Original Author
    15 years ago
    last modified: 9 years ago

    Mmhmm - that will make a very fast soil if you're using it at 5:1:1 or close. I don't screen the partially composted fines that I use in the 5:1:1 mix & use 1/4" pre-screened fir bark in the gritty mix.

    Al

  • nathanr
    15 years ago
    last modified: 9 years ago

    Hi Al! I think of your advice to us often and I always try to follow the principles of good container media that you have so generously shared with us. For all of this I thank you. Now I have a specific question regarding the levels of dolomitic lime you suggest to use in your pine bark fines based mixture. Your post at this website from March 19, 2005 specified to use "1 cup lime" in your big batch recipe. Now at the beginning of this post, you recommend that "2 cups lime." On checking pH of mixes made with 1 cup lime/big batch, I found it to be around 6.0 to 6.5 pH which would be a good pH range for most lime-requiring plants. What accounts for your change of lime levels?
    Thanks so much Al.
    Nathan

  • tapla (mid-Michigan, USDA z5b-6a)
    Original Author
    15 years ago
    last modified: 9 years ago

    4-6 lbs of dolomite will generally raise the pH of 1 yard of media by 0.5 - 1.0 point. 16 (fl) oz of dolomite weighs about 1 lb, so we can use ounces interchangeably (fluid vs weight) for lime. Bark/peat soils usually come in at an unlimed pH of 4.0 - 5.0, so we want to raise them about >1.0 point.

    There are 80 oz in 5 lbs of lime, or 160 tbsp, which will raise the pH of a yard (202 gallons) of soil about 1 point. The big batch is about 35 gallons (4.5 cu ft) or 1/6 of a yard. We need 1/6 of 160 tbsp or 27 tbsp to raise the pH about 1 point. There are 16 tbsp in a cup, so 27 tbsp is 1.7 cups. Since we need to raise the pH more than 1 point, we round the 1.7 cups up 0.3 cups to 2.0 cups.

    The change comes as a result of realizing that supplying a single cup of lime might not have raised pH high enough. This can ensure that Ca remains reactive and relatively unavailable instead of (in the case of adding more dolomite) residual and exchangeable.

    Al

  • esteban_2009
    15 years ago
    last modified: 9 years ago

    Test

    Steve

  • esteban_2009
    15 years ago
    last modified: 9 years ago

    I lost my first post, the reason for a test message.
    Is Pine Bark Compost and Pine Bark Fines one and the same?
    Thanks to all who respond.
    Steve

  • tapla (mid-Michigan, USDA z5b-6a)
    Original Author
    15 years ago
    last modified: 9 years ago

    Pine bark fines are just pine bark that has been chipped or ground to a fine size. It may or may not be composted or partially composted. Partially composted pine bark fines have composted in piles, usually from one harvest season to the next.

    The thread has reached 150 posts, so please follow the link below to the new thread, if there is interest.

  • jennp9
    3 years ago

    I just transplanted my current house plants into larger pots but accidentally used GARDEN soil as the supplemental soil to fill the remaining space in the larger pots. Should I take them out now and transplant using a potting mix? or will they be ok since the amount of garden soil I used is minimal compared to the bulk of the plant/roots transferred? (I used the garden soil at the bottom and to “top off“ the plants).

    thanks in advance for your help and suggestions.


  • tapla (mid-Michigan, USDA z5b-6a)
    Original Author
    3 years ago
    last modified: 3 years ago

    Hi, Jenn. This thread has been dormant for 11 years, and I've been trying to guide contributors to the newest repost of the same info. What I'm going to do is leave this note so others get the idea there's a much more recent version that's active. I'll copy/paste your message to the new thread, then answer your question. Just click this live link, then scroll down to your question at the end of the last text box.

    Others - please do not ask questions here. The newest version of this topic can be found if you Simply Click This Link. Thanks for your help.

    Al