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

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 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 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, water’s 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 ‘perch’ (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 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.

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 haven’t 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.

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 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 ˝ 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.

Al

If there is additional interest, please review previous contributions to this thread here:
Post VIII
Post VII
Post VI
Post V
Post IV
Post III
Post II
Post I

Some readers might also be interested in a discussion about fertilizer strategies for containerized plants at the link below.

Fertilizer Strategies for Containerized Plants

Thanks again, for your interest and for making this fun. ;o)

Al

Wow another new life for this thread! It's amazing that so much good information can be found in a single thread.

I'd like to thank Al for starting this thread four years ago and for all the great posts from GW members over the years! You all make this forum such a great place to share information. Virtually *anything* you'd want or need to know about growing plants in containers can be found somewhere within this 9-part thread.

Thanks again to Al for starting the thread, to GW for hosting the thread, and for the members who contributed so much info to the thread.

Regards,

Dave

I would sever the cutting with a razor-sharp, sterile tool, dip in sulfur powder, leave it on the bench for a week or two, then pot into terra cotta, using dry gritty mix & wait another week before I started misting the soil ever so slightly. I've had jade (and many other succulents) that were on the bench for several months with cut ends that were not in soil (just hanging out in the air) that were putting out roots. Recently (May), I potted 6 cuttings of Aeonium arboreum atropurpureum 'Schwarzkopf' that were on my basement grow bench all winter. They were also growing roots in the air and struck quickly after potting them up.

Al

I misunderstood things to begin with, got confused a bit but I am sure you have a better way of explaining things Al.

Again I hope this exchange helps at least a few people

Shannon

I didn't realize that Kashu had a fair amount of experience, so forgive the probably too specific advice. I think he has it right in his understanding that water isn't much of a priority for a good while when propagating this plant from cuttings.

I'll send you your finder's fee, Shannon - if you promise to drop the Almighty thing. It's embarrassing for me - I'm perfectly happy to be thought of as just one of the regulars. ;o)

Al

I think most of just want to offer some tried and true experience, not necessarily to be right but to offer some kind of explaination. (Or so I thought...)

Finder's fee: I think Kashu had already been around and prolly heard of you before... I'll take you up on that anyhow =D

Shannon

Thanks

Shannon

Your answer: It depends on the plant and the time of year. Ideally, almost all temperate plants would have all the soil removed during a spring repot, and tropicals the same, but the work would be done in the month before they exhibit their most robust period of growth.

Some plants just don't lend themselves to having all the soil removed, so for those plants, we do what experience tells us is reasonable. Hmmmm - as I think about it, most growers reading this wouldn't think removing soil from a plant's roots is in any way reasonable to begin with, so maybe that's not such a good gauge, eh? ;o)

You're going to be quite safe if you remove 1/2 of the soil at the first repot by cutting 2-3 pie shaped wedges out of the roots & leaving the rest of the roots/soil intact. Next spring, you can remove the older soil from the roots that remained last time. Surprisingly, plants recently repotted might sulk for a short time, but they almost always end up overtaking and passing, in mass, a counterpart that might not have been repotted by the end of summer or the growth cycle

It's not a good thing to have dissimilar soils in the same container. One soil will usually be too wet while the other is too dry.

Take good care GG. ;o)

Al

I realize its not the best time to do so but they are having mood swings in their current conditions.

I need to repot several peppers into larger containers because I can not water 4 times a day (which they are now requiring). One of the plants was started with pepper seeds someone brought back from Mexico, so if I messed it up my DH would be pretty upset with me... tstl!! (to say the least) :D

Shannon

Is this right? If not, what are the rules? Thanks.

Since the gritty mix has a higher starting pH it can't afford the boost in pH that the lime gives, so I elect to use CaSO4 (gypsum) and MgSO4 (Epsom salts) to supply Ca/Mg.

Al

iam sorry to hear about your bad misfortune the other day!!.

can you answer a question for me as best you can?, do
you think veggie,s can be grown in nothing but turface ?,
they would be grown in twenty five and thirty gallon
container,s fed at 1/4 or 1/2 strength f.p., what would
be your best guess as to watering cycle.s ? it is very
hot here, thank,s.

les matzek

There's no way for me to guess at how often you'd need to water. It depends on whether or not you screen, weather, how much plant mass is in the containers in relation to the volume of soil .....

Al

how does turface hold water compaired to hydroton ?.
not postive veggie,s can grow in turface ?, thank,s al

les matzek

Personally I would be afraid to use hydroton in an outdoor application as the watering frequency would likely be insane. Works fine indoors with houseplants though.

Paying less than $5.00 for a 50# bag of turface is a good price I believe. I don't recall seeing it for less than about $10 in my area.

I don't buy it often and there aren't many turface retailers in my area but I'd be happy paying $5.00 for 50#. I'm sure if you buy it by the pallet like Al probably does it's quite inexpensive as well.

Dave

the last two weeks here have been past 100 degrees do
you have any ideas why it is growing so slow ??.

the plant looks very healthy tho, regards.

les matzek

It could be the temperatures - any idea what the afternoon soil temps are? Can you shade the containers to keep the soil from heating up? You really don't WANT it to wilt, but I'm thinking you should hold on the watering and keep a close eye on it as you let it go to just barely the wilt stage at least once in the near future so you can gauge if you're over-watering.

When is the last time you fertilized - with what fertilizer - and at what strength (full, half ....)?

Al

I am a newbie gardener and you would cringe at the state of my containers (I'm currently using a mix of garden soil from the backyard and compost, not even a peat based mix from a box store). I have alright results (plants grew and bloomed), but for the ammount of effort I put into them, I expect better returns!

I'm so glad I stumbled upon your thread. I'm already gathering supplies for next year (you guessed it, new soil mixes). The big box stores were no help to me. I'm fortunate to live 6.5 miles from a turface dealer (she actually asked how many tons I wanted). So I ordered 100 pounds of MVP. I was able to find pine bark mulch (4 cubic feet), but I'm not happy with the coarseness of the product. I'll have to screen it somehow to get rid of the big stuff or keep looking for better fines elsewhere. A trip to the local feed and seed store found granite grits (coarse, 100 pounds).

The feed and seed store also sells perlite in 4 cubic foot bales. The box stores all sell sphagnum peat moss in 2.2 cubic foot bales. I'll get a CRF and mirco nutrient mix next year closer to the growing season (from what little I understand, fertilizer doesn't store well)

Other than quality pine fines, I believe I've found everything needed to make your 5-1-1 and gritty mixes. I plan on experimenting with an all turface mix, gritty mix, 5-1-1, and some kind of peat based mix.

I just wanted to thank you for sharing your knowledge with us beginners.

-Mike

A few offerings:

* For the pine bark - look for a product where (practically) all pieces are smaller than a dime. Partially composted for the 5:1:1 mix is better, and uncomposted 1/8-1/4 pieces are best for the gritty mix

* Gran-I-Grit in grower size, or #2 cherrystone is best for the gritty mix

* If you use a 3:1:2 ratio (do you understand ratio vs %s?)soluble fertilizer like MG, Peter's, or Foliage-Pro, you won't need the micro-nutrients, but be sure you lime the 5:1:1 mix and add gypsum to the gritty mix & then add Epsom salts when you fertilize (read up on it above or in the other threads, or ask)

* Fertilizer stores fine. You just need to try to keep moist air away from the small open bags of granular soluble fertilizers like MG and Peter's.

Al

The pine mulch I bought is going to be just that, mulch. I'll keep looking for fines (I have all winter). Perhaps the seed and feed store sells fine pine as bedding or something. Just the excuse I needed to look around the store a little more :).

I have a 50 pound bag of garden lime (from a previous project), but its a fine powder. Will that work or should I look for the coarse stuff?

I've seen bags of gypsum at the box stores, I'll be sure to pick some up along with the CRF (Any particular flavor I should look for?).

The water soluble fertilizer (Schultz) is 24% 8% 16% which is a 3:1:2 ratio if I remember my math correctly. It saids "with mirconutrients". I think I have Epsom salt somewhere.

Thanks

-Mike

For the 5:1:1 mix, look for soil conditioner, aged pine bark, or other products labeled 'pine bark'. If you can find Fafard's aged pine bark, it will work well, but you may need to increase the perlite's presence as I've found it a little to water retentive for my taste, but then I generally grow in mixes even more coarse than I describe here.

The powder, if it is labeled 'dolomitic lime' is likely the same as the prilled (pelletized) version, except that it hasn't been prilled. Look to see that there is 2-4x as much Ca as Mg, and you'll be fine. If there isn't, I would look to another product - to make things easier on yourself.

Make sure you get the lime/gypsum/Epsom salts thing clear in your mind before you move forward.

Al

I think I'll just buy new dolomitic lime to be safe (and use the other stuff on the lawn).

I think I have the start of a grasp on the lime/gypsum/Epsom salt thing. I'll have to do further reading of course :). Here goes.

The dolomitic lime, which is CaMg(CO3)2, is used in the 5:1:1 mix to supply Ca and Mg (at 2-4x more Ca than Mg), and to raise the pH (because the peat moss lowers it, and the lower the pH, the tighter P is held).

The gypsum, which is CaSO4*2H2O, is used in the gritty mix to supply Ca.

Epsom salt, which is MgSO4*7H2O, is used to supply Mg to the gritty mix because most water soluble fertilizers don't contain Mg or Ca (I checked mine, and it doesn't). The Epsom salt is added at the rate of 1/8 to 1/4 tsp per gallon of fertilizer (which is 3/4 to 1 tsp of fertilizer per gallon of water)

Water with a weak solution of 3:1:2 fertilizer every watering because plants absorb it better at low concentrations. When watering, 10 to 15% of the water applied should pass through the drain hole to "flush" salts from the soil.

-Mike

Al

Hey sounds like you have a great handle on both the 5-1-1 and gritty mixes! It took me a long time to find all the ingredients and figure out the fertilizer side of things, but once you do some reading of this thread and the previous eight threads it does make sense. Al was most generous with his time, both on and off-list, and answered many of my "newbie" questions.

I'm sure your plants should respond much better using these soil mixes next season. My trees are showing huge root growth this season in the gritty mix.

Granted, hunting down the ingredients, sifting fines, and mixing the soil it is a bit more work than just buying a bag of MG potting soil, but I have no doubt that in general plants grow better in the 5-1-1 and grit mixes with proper fertilization, watering, drainage and air movemnet through the root zone. The peat in the MG soil acts like a sponge and retains far too much water for far too long, preventing air from getting to the roots and keeping the roots soggy.

I agree that typically the big box stores are not very helpful when it comes to finding the right ingredients for the soil mixes. Granted, a few list members have found the right size of pine bark, turface or even silica sand at a HD or Wal-Mart but typically in my area you have to go to local hardware stores, feed stores, etc. to find the ingredients. In my experience, if you go to HD or Lowe's and ask for turface no one has any idea what you are talking about. Sounds like you've already found some great sources for your materials!

Good luck next season and be sure to keep us posted on how your plants do in the new mixes.

Thanks

Dave

thanks ,

les matzek

Al

The concolor fir trees are the largest and oldest trees, and they have roots as long as 3 or 4 inches sticking out of the containers, and they were heavily root pruned this past April.

Even the tiny 2nd season white spruce seedlings have roots sticking out of their containers (actually aquatic plant baskets).

Remarkable growth for sure, probably due to the great gritty mix soil and the the regular feedings and waterings. In addition, the trees get direct morning and early afternoon sunlight, but late afternoon shade, which helps protect them from the very hot afternoon sun.

I have no doubt the gritty soil and watering/fertilizing schedule made most of this dramatic root growth possible.

Thanks Al, JAG and everyone who answered my *many* questions.

Dave

Al, I screened my floordry #8822 and came away w/ about a quart of fine powder/dust size particles. Wouldn't that clog up the 5-1-1?

Are you saying there's no need to screen the floordry? I thought you didn't screen turface?

If I was using Turface in the 5:1:1 mix, I wouldn't screen it, but I always screen it for the gritty mix. Of course, that's not carved in stone either, it's just what I've found to suit my own purposes/needs best.

Al

Less well known is the fact that sphagnum moss has a high zinc content in the form of a naturally occurring antibiotic called Tropolene. The anaerobic bacteria that cause decay in wood are (at least partially) nullified by the antiseptic properties of sphagnum moss. Hence, pure sphagnum (without the addition of any other organic material) is an ideal medium for re-invigorating weak plants, and plants with root-rot.

Al

I read in earlier threads that the pH of the 5-1-1 mix is low so I'd have to add about 1 tbsp of garden lime per gallon of soil to raise pH and to add CA and MG. A few years ago I checked our water supply and the pH was high, around 8 or so. Does that make a difference in how much lime I add to the soil mix? Does using high pH water raise the pH of the 5-1-1 soil mix over time?

Thanks

John

Can't answer your question because pH CAN be high and alkalinity low. Water with a high pH isn't a problem unless the alkalinity is also high. Water with high alkalinity will raise the pH over time, but water with a high pH and low alkalinity would have considerably less affect.

Al

For the 5-1-1 mix I will substitute granite in place of the perlite until I use it up. The pea gravel I will use in my driveway lol...

Sorry I should have mentioned that my water is high pH and high alkaline too. I dont remember the exact number but when I tested it I remember that both numbers were high. pH around 8 and alkaline somewhere over 100ppm, maybe 120 or 130.

I read that JaG recommended vinegar to lower pH if that's an issue.

I tested it I remember that both numbers were high. pH around 8 and alkaline somewhere over 100ppm, maybe 120 or 130.

I read that JaG recommended vinegar to lower pH if that's an issue.

If your alkalinity number is just over 100 you really have nothing to worry about. My water is pH 7.5 and alkalinity is just over 400 mg of CaCO3/L even though the alkalinity isn't entirely caused by CaC03. I use vinegar to reduce the alkalinity of the water so it can't shift the pH of my ground and container soils. The TDS (total dissolved solids) is just under EPA regulated levels so my situation isn't the norm. I have to use an RO/DI filter for aquariums or I would end up killing my aquatic friends (or at least shortening their life span)

Until very recently I was confused by how vinegar could take the water from pH 7.5 to 6.0, but alkalinity remained around 150 mg/L

I have since learned that counter intuitively (to me), pH needs to be lowered to 4.5 in order to remove all the alkalinity. I will have to test this to see if it works out.

Anyway, my above rambling probably isn't all that helpful to you. In your case I wouldn't recommend adding vinegar to your water as it really isn't necessary. You *could* if you wanted to, but I only add around 1 ounce per 4 gallons to take the pH down about 1.5 points and drop alkalinty from over 400 to around 150. In your case a few drops per gallon would probably do it, but your water is already lower in alkalinity than my acidified water.

Al

Just didnt want to raise the soil pH too high with the water.

Thanks

John

http://www.moltan.com/Industrial_DE_Clay/industrial_absorbents.html

Thanks!

Dave

Al

Napa Floor Dry P#8822 is calcined DE. Some people have also been using cat litter made of calcined DE.

Where is this available? I'd like to get bigger bags than the napa floor dry.

The local NAPA store does not carry the NAPA Floor Dry 8822, instead they carry OilDri! I'm sure they could order it, just found it odd that a NAPA store would stock OilDri but not their own brand.

Thanks!

Dave

Looks like I have an overly moist growing area (which I've tried to on account of the orchids but which also adds to spider mite infestation problems.) as well as a lot of other temptations for insects and creepy crawlies in the other plants.

After reading through some of the soil problems on this forum and houseplants forum, I first trashed all the egg shells, mango seeds, etc., then cleaned up my soil using a home recipe of household detergent and oil mix, and then decided to start repotting all the plants afresh.

In almost timely fashion, I came across your soil analyses, and armed with your soil recipe visited the local Lowe's.

I came across pine bark mulch (shredded variety - didn't look dime-sized like you stated) and pine bark pellets which were much larger, so couldn;t decide what to opt for; no one there seemed to understand what pine bark "fines" were supposed to mean. Then the woman there argued that pine bark mulch was not at all recommended for indoor use as it was not sterilized, and the miracle-gro product she had was the best answer for indoor potting soil, so that's what I bought as I had to make a decision then and there; I also brought some pea pebbles as I read somewhere here I think, that a layer of it on top of the soil would discourage insects from burrowing deeper to lay eggs...

I haven't yet repotted the plants - but what would you do??
Firstly its September already, and would the plants survive the winter (DC/MD area) in new pots and with roots pruned etc - I dont know what condition their roots are in in the first place. Or should I just wait through winter, reduce watering, till then?

On the positive side however, my oncidium is just beginning to bloom, and the divided sections of the cattleya have begun a root and a bulb respectively, and the dormant phal has also begun to spring a root..., and there's a new leaf on the angel wing begonia :)

I won't tell you now is a good time to be repotting houseplants, but if it's an emergency, what are you going to do? It's probably more likely you'll lose them to a water-retentive soil over winter than to the effects of a repotting. Too, I think you're in pretty good shape if you know you can provide good light & some warmth (like a sun room) this winter.

Your turn. ;o)

Al

Kyle

I'm not Al, but if you are looking for various sizes of screening I'd look at your local hardware store. Any hardware store should have screen/hardware cloth in various sizes at very reasonable prices.

I recently purchased some insect screen for various household projects and it cost me about $6.00 for a 10-foot roll.

So any hardware store should carry it. The big box stores should carry it as well.

pardak

Keep us posted on your progress, Green .... Good luck.

Al

I just made a batch of Gritty mix for my new dwarf naval orange tree and... WOW. It drains FAST. So fast that I can't water log it with the hose full open. Given that, I'm a bit apprehensive.

My exact mix:
1 Part Screened 1/2" - 1/4" Pine Bark
1 Part Bug Screened OilDri (Tested to be sure it doesn't break down)
1 Part Bug Screened Orchid Pumice

I used pumice and OilDri because I figure I want the higher water holding capacity.

First, its supposed to be that fast, right?

Second, I'm in Las Vegas and I worry about the water holding capacity. I am thinking of moving the tree from its nursery pot (#5) to a Homer 5 gallon bucket (seems a lot bigger than the #5). I could also make up some more mix and use a big 18 Gallon round tub I have. Should I pot it up in the big tub?

If I need to I'll hook it up to a timer drip system to water it a few times during the day in the summer.

Thanks for your help.

I am using a modified 511 for some citrus as well as the gritty mix for some others.

I am in Wisconsin rather than Vegas, of course.

My impression of the 511 in 16" pots is it drains well, but holds water longer than I would like. This is particularly true indoors over the winter, but even in the summer. The gritty mix I find a much better choice, but even with it's instant drainage it holds water longer than I would prefer. During the summer I don't have to water more than once every few-several days. I can water more often due to it's outstanding drainage, but don't need to.

I will be interested to see what your watering interval becomes in the summer. I would be at least a little surprised if it was more than daily.

Because the soil you made probably holds no perched water, you're not restricted by the container size considerations you have to take into account when using slower soils. IOW, you could grow a very small plant in 100 or even 1,000 gallons of soil if you choose, with no unpleasant repercussions.

Good luck!!

Al

Thanks for that reassurance and information. I am going to re-pot the Orange tree tonight from the nursery's pot/soil to an 18" pot and gritty mix.

The batch I mixed up and watered down a couple days ago felt real dry in the first couple of inches. When I dumped it out into another container I could see that it was moist and I could tell the amount of water collected as a film on the particles was relatively large. I think I understand better now.

Thank you for you time and assistance!

Al

Al

Looks like I will have to keep an eye on it myself now... =( I too boiled it, froze it, etc... and it seems to be fine (right now). Thanks for that heads up.

Feels like I've got time bombs in my back yard waiting to explode now.

I lucked out, however, and found some granite chips in the poultry section of our local Rural King, a large farm oriented store... kind of like Blain's Farm & Fleet... it's called Manna-Pro Poultry Grit, and it's the perfect size granite chip for using in Al's Mix.

A note to Al... I'm once again busy spreading the gospel of medium to all my bulb compadres! It's a new season for our bulbs, and several new bulb lovers have joined our group. I cringe when I hear about some of the things used in containers, but I've been privileged to use a better medium for a while now, and I see the healthy results.

I'd love to be able to recommend a book about soils to my gardening friends... but you haven't been published yet! Hint, hint!

I've been published in hard copy magazines and several online magazines, and tons of newsletters that have asked permission to publish some stuff I've written I'd never have dreamed there would be interest in, but I just can't get past the 'daunted' stage when it comes to undertaking a book. I had a dear friend who offered to do most of the organizing if I did the writing, but now she's going back to her home in Sweden, which makes it all seem even MORE daunting. It looks like that will have to be a project for when I retire ...... if I still have all my marbles. ;o)

BTW - thanks for the kind words, my friend. The offer of help stands.

YPA

Well, I really hope you do eventually publish a book... to have all your experience and thoughts conglomerated into a garden book would be so great for the beginning gardener, and a good guide for those of us who are a little forgetful! When it comes to my bulbs, you've saved me an untold amount of heartache... and now, there's no rot or fungal issues whatsoever, and roots are as healthy as they can be!

Writing a book is a daunting undertaking... my husband is constantly hounded to publish one on his experiences in breeding and the American Bulldog, but where do you begin? And how do you go about arranging all those random thoughts and stories, you know? We're in a few books and videos and magazines, too... but I'd still like to see you, and my husband, come out with your own books! Someday... :-)

When I finally get to the point where I need more than just a small batch of Al's Mix, I will ask about locating large quantities of turface and pine bark. Thanks for the offer of help with locations!

Happy Gardening!

Al

N San Antonio
15480 Capital
San Antonio, TX 78249-
Phone: (210) 479-2888
Fax: (210) 479-2112

S San Antonio
17141 Benton City Road
Von Ormy, TX 78073-3925
Phone: (210) 622-9634
Fax: (210) 622-9637

Glad you stuck around to hang out with us. ;o)

Al

http://en.wikipedia.org/wiki/LECA

I would consider it more comparable to Turface MVP or Napa Auto Parts Floor Dry in that it is very water retentive while perlite and granite are not.

My understanding is that LECA is made in a very small size, but I personally have never seen it. Around 1/4" pieces is the smallest I have ever seen at a hydro store.

Al

Al

I think if you know what the purposes are for the different ingredients, it would make it easier to find items to substitute. I read a very interesting website on bonsai, and they give some suggestions for medium ingredients in other countries. I'll include the link here... be sure to check out the whole site... it's extremely interesting and educational!

Al

I use Perlite extensively, along with bark and pumice, and it sometimes *seems*
as though all the water is simply passing through the medium. However, more
water is being retained than one might think.

Josh

If you think it needs another more water retentive ingredient, you could always add a little vermiculite or turface... I know there are other ingredients that would do the same thing... check out the listing of medium ingredients in the link below. There are even products listed available in Germany!

Al

Once I can obtain some turface, I'm definitely going to add a little to the current mix. I think the mix is fine as is, but I do think a tiny bit more moisture retention would improve it.

Switching from a finer, peat based potting soil to Al's Mix takes a bit of getting used to... but once you find a happy watering/feeding schedule, it makes all the difference in the world to the plants and their roots!

In the 5:1:1 mix, when the bark gets dry, the peat is dry, too; so almost the entire soil becomes hydrophobic & difficult to rewet. That isn't the case with the gritty mix when it's made with either Turface or calcined DE (floor-dry). The Turface/floor-dry doesn't get hydrophobic, so even if the gritty mix is completely dry, the Turface or DE readily soaks up water, then the water diffuses into the bark, breaking it's water-repellency with no problems and with only one quick watering.

When I make the 5:1:1 mix, I make it on a tarp, usually late in the day. As I'm pulling the edges of the tarp to turn the soil over & mix it, I keep misting it with the hose. When it's mixed, I just fold the tarp over the soil & by AM the water has diffused into the soil and broken its water-repellency.

I wasn't really suggesting a way for BK to wet his soil; rather, I was trying to help find a way for him to judge just how much water the soil holds. I hope it works out for him. ;o)

Al