Container Soils - Water Movement and Retention XVII

6 years ago

Container Soils - Water Movement and Retention XVII

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

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

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

Is Soil X a 'Good' Soil?

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Container Soils - Water Movement & Retention,color>

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

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

Consider this if you will:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

I always remain cognizant of these physical principles whenever I build a soil. I have not used a commercially prepared soil in many years, preferring to build a soil or amend one of my 2 basic mixes to suit individual plantings. I keep many ingredients at the ready for building soils, but the basic building process usually starts with conifer bark and perlite. Sphagnum peat plays a secondary role in my container soils because it breaks down too quickly to suit me, and when it does, it impedes drainage and reduces aeration. Size matters. Partially composted conifer bark fines (pine is easiest to find and least expensive) works best in the following recipes, followed by uncomposted bark in the Bark fines of pine, fir or hemlock, are excellent as the primary component of your soils. The lignin contained in bark keeps it rigid and the rigidity provides air-holding pockets in the root zone far longer than peat or compost mixes that too quickly break down to a soup-like consistency. Conifer bark also contains suberin, a lipid sometimes referred to as nature's preservative. Suberin, more scarce as a presence in sapwood products and hardwood bark, dramatically slows the decomposition of conifer bark-based soils. It contains highly varied hydrocarbon chains and the microorganisms that turn peat to soup have great difficulty cleaving these chains - it retains its structure.

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

The basic soils I use ....

The 5:1:1 mix:

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

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

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

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

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

The gritty mix:

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

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

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

Post XVI
Post XV
Post XIV
Post XII

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

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

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

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

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


This post was edited by tapla on Mon, Jun 10, 13 at 17:06

Comments (189)

  • hairmetal4ever

    For dolomitic lime, when and how much should I have to reapply and topdress after the iinitial shot?

  • oxboy555

    None. Never. Just the initial shot.

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  • greenman28 NorCal 7b/8a

    Hairmetal, Dolomitic Lime is applied 1 Tablespoon per gallon of mix you make.


  • oxboy555

    I say 'never' but I suppose if you watered only with distilled/rain water and used a urea/ammonium based fert, you could be in danger of crashing your 5-1-1 pH below say 5.0. Not a death sentence for blueberries and azaleas, but adding periodic lime would stabilize that situation up closer to the mid 5 pH range that we all kind of shoot for with your typical container plantings.

    If you water with hard, high-alkalinity water and don't have the opportunity to flush your pots fairly regularly, do NOT add lime ever after the initial shot. That would likely be a death sentence after a while.

  • hairmetal4ever

    I'm not sure what the stats of my water are - I can't seem to find the data.

  • oxboy555

    It's pretty important to know. Call up your water provider and hound them for their water quality reports. You at least want an idea of the alkalinity (really important to know IMHO), avg pH and the relative strengths of included micros like calcium, magnesium and sulfur. It's also nice to know the hardness and TDS/salinity.

    Failing this, you can at least go buy alkalinity test strips at a pool supply store. Look for 'alkalinity' specifically, not pH or hardness (although those are related and nice to know). It's important to know the concentration of minerals/salts/particles that your irrigation water (read: tap for most of us) natively adds to the potted environment. This in turn tells you how often you need to flush, whether to add vinegar/acid to your irrigation source, whether to change your water source entirely (rain/distilled if that's an option), what type of plants may tolerate your unaltered water chemistry from the tap, etc.

    Some may call this nerdy and overboard, but then they wonder why their plants turn yellow and fail after 3 mos. It behooves us to put on the lab coat and learn a little bit about water chemistry, plant nutrition, soil composition etc. Reinforcing this desire to learn is Al's and the other experts' greatest contribution to this forum. I find it fascinating and our plants can only benefit from the more info we absorb and apply....unless of course we end up killing them with kindness, that is... and none of us have ever been guilty of that! wink-wink :)

  • hairmetal4ever

    Maybe I missed it in the thread - but how much mix do you end up with? For the 5-1-1, since particles fall together, having 5 cu yds of bark, 1 cu of peat, 1 cu of perlite won't result in 7 cu, it will be less.

    Same question for the gritty mix.

  • oxboy555

    Yup, you're right -- it condenses once mixed.

    I don't know - maybe 15% less?

  • hairmetal4ever


    From Baltimore City Water reports (they supply our county water here):

    pH averages 7.9 - 8.0
    Zinc varies from 0.0005 to 0.013 ppm (2 seperate treatment plants, the water all runs through the same lines)

    This data is from a home brewer's forum from 2009, but it's a start. That's an idea, anyway:

    Ca 24.2
    Mg 6.6
    Hardness 91
    Alkalinity 53
    Sodium 14.5
    Chloride 36
    Iron Mn 0.01
    Al 0.06

  • tapla

    Thanks to everyone for making this such a fun and popular thread!

  • tapla

    Here's a link to the new thread.

    Thanks again!


    Here is a link that might be useful: Continuation of this thread

  • oxboy555

    If your alkalinity is really 53ppm, you're in great shape. It's the perfect amount between keeping your soil pH stable and avoiding a rapid accumulation of minerals in said soil (which is what can happen if you have 120+ ish ppm like I do). Flush your pots completely every month or so in summer and once or twice between fall and spring if you can. Water so only 20% at most comes out each time so you're not flushing all your fert particles out with each watering.

    I would still try to find a more "official" and more recent report from your water district. Or spend the $5 at the pool supply store for the text strips to confirm. I'm kind of OCD and want the peace of mind so that's what I did.

  • Whitney Harmon Stoskopf

    Hi. I may be over thinking, and this may be stupid, but how do you measure by volume. I read several comments saying the equal parts were by volume. Shoot. I just measured by 5 pints of each prepared ingredient( size of container I had

  • four (9B near 9a)

    Choices from there are to go with what you have (equal parts), or to adjust to get some other ratio.
    If you want 5:1:1, then add twenty of first ingredient.

  • tapla

    WHS - If you're making the gritty mix, which is equal parts by volume of screened Turface, screened grit, and screened pine or fir bark, it doesn't matter what size container you choose. It could be one pail full of each ingredient, a bushel, a cup, ....... If you're making the 5:1:1 mix, you would use 5 scoops (any size) of screened pine bark + 1 scoop each of sphagnum peat and perlite + an appropriate amount of lime. The pine bark for the 5:1:1 mix doesn't need to be screened unless it has a significant fraction of particles larger than 3/8" or it has a large fraction of fine particles from dust to 1/8"


  • fidgety

    Hello Al, I cannot easily get Turface around here, but I do have a supplier for Kyodama. The supplier says: "is a fired clay product with high porosity and a good CEC (cation exchange capacity) and excellent moisture holding capacity.
    The product has a very high mechanical integrity and is completely
    frost proof, this ensures that the granules do not break down, even
    after many years in the pot. Particle size 2mm-5mm". Does this sound OK to you ? photo

  • halocline

    Hi Al,

    I recently posted some instructions & advice on the thread "Indoor Gardening for 2017" in the "Growing Under Lights" forum. Here's the latest post from the person I was communicating with.

    Bit Brush

    "Want to give everyone an update - I followed the soil recommendations @halocline posted and my plants are doing INCREDIBLE. I have never seen such a positive reaction from any of my plants - even when I tried last summer to make my own compost soil. I highly recommend others follow the guidelines established in this post for success.

    Container soil water movement and retention

    Growing lavendar, rosemary, basil and got our succulents potted into this soil. Planning on setting up grow lights on our baker's racks from IKEA this fall once the sunlight in my window boxes subdues."


    tapla thanked halocline
  • tapla

    Fidgety - If you have a 4mm screen, I'd screen it and use only what
    does pass a 4mm screen and doesn't pass aluminum insect screening, the
    later being more about removing the dust. If you have to use the
    fraction containing larger particles, you'll need to be careful that the
    bark and grit aren't overly large, too. If I was using all of the
    Kyodama, I might even be tempted to increase it's volume in the soil.
    Like 3 parts bark, 4 parts Kyodama, and 2 parts grit.

    BTW - Kyodama LOOKS like Haydite. Do you have a link that definitively tells us what Kyodama is made of?


  • halocline

    Here's some pics of Haydite correctly sized for use in the "Gritty Mix"; which I procured through a specialty supplier (That no longer exsists).

    (Haydite in comparison w/ grit)

    (The type of grit I use. "Insoluble Granite")


  • myermike_1micha

    Al, could you please take a close look at this thread and correct ant misinfo if there is any?

    I certainly know you can help out and I really appreciate that!! Hope all is well.

    Hope everyone is well. Many things going on and I will be back! Hugs to all I know.


  • halocline

    mike - I clicked on your link, and then unintentionally read the majority of that thread.

    I tried to put forth some beneficial information, and, some constructive criticism. ;-)


  • halocline

    I'm going to do an experiment similar to what I did w/ my Adeniums. I bought 2 Pachypodium lamerei (Madagascar Palms), and I'm going to put one in the Gritty Mix, and the other in my Adenium mix.

    These were both grown in California, and there's one slight difference. The second one has a baby near the base.

    I have two other Pachy l.'s. One is 21" tall, and the other is 6".

    The big one is in need of a transplant, but I've been putting it off until I have an extra set of hands. In spite of it's cramped conditions, it's growing like crazy!


  • halocline

    The tall one (above), is still in the same pot I put it in; two years ago when I bought it. I'm pretty sure it's in the Gritty Mix.





    (11/25/16 New & old)


  • Andi C

    my 5-1-1 and 3-1-1 are having some drainage issues.

    whenever I water them, the water seems to be flowing directly down and out the drainage holes. some areas of the container remain dry even after watering/fertigating.

    this seems to be happening with multiple containers (10g, 15g, 25g)

    any advice?


    5-1-1 and 3-1-1 soil.

    x3 wax Jambu in 10g containers - up potted from 3G nursery pot in the spring. the roots appear matted and almost overgrown already

    15 & 25g container lychees. up potted from 3G containers also. slower growers and roots starting to extend to the container edge.

    every 48h (at 1pm) gets spout spitter spray on the leaves and soil. also gets watered 1-2 times/week by hand.

    zone 9b. black containers baking in the sun (7am-4pm) - highs 95, lows 75. humid weather but rains only every 2 weeks so far

  • halocline

    Andi - Just by reading your first two sentences, I believe I know exactly what the problem is. Your soil has become hydrophobic ("tending to repel or fail to mix with water.").

    Did you just recently make your soils, or have the materials been stored for a length of time?

    The organic components in your soils; like Pine Bark, Sphagnum Moss can become hydrophobic when they are allowed to dry out for an extended period of time, and it can be difficult to reverse the issue. Basically, a waxy like substance has built up on the organic materials in your soil; causing the water to run off the soil surface, like water off a Duck's back. It's actually more complicated than that, it has to do with polar, and non-polar molecules. Here's a link to Wikipedia on the subject.


    There are different ways to deal w/ this. Try taking a long skewer (or similar), and poke a bunch of holes deep throughout the soil surface, and water slowly for a long period. Or, better yet, if you have a container (bathtub maybe) large enough to soak the entire pot for 2-4 hours (maybe longer). I would use slightly warm water. This may have to be done more than once.

    Or, you could go the scientific route, and use a surfactant.



    You may find that some people will suggest using "Dawn" dishwashing liquid. Although it does work, I would only recommend using it as a last resort, and at very low concentrates. If you should try using this method, USE ONLY "DAWN DISHWASHING LIQUID" (the Blue stuff). Begin with one SMALL drop per Gallon of water.

    Good luck,


  • Andi C

    thanks Rob.

    can hydrophobicity develop months after planting?

    these plants were potted 3-5 months ago and drainage was excellent until the past month. only difference between now and before is that it's summer (hotter) and the plants have grown.

    maybe i could plug up the drainage holes and water?

  • andrewraz

    Yes, it certainly can develop months after planting. Basically any time the soil has a chance to dry completely it can become hydrophobic. It kind of becomes like sand, and water just basically pours straight through. Summer is a prime time for it to happen. Higher temperatures and more direct sun contribute to quicker evaporation directly from the soil. In the spring plants are putting out tons of shoots, but later in the season they focus more on root growth, and that means more roots absorbing water from the soil. Couple that with the summer temps again, and the plant is loosing water out of its leaves, so it sucks up even more water. Voila, drier soil. I'm fighting that with a couple of mine too.

  • halocline

    Andi - You said that you "up-potted"? So I assume that the old soil was left intact, with new soil added to fill the new extra space. When this is done, what often happens is, the original soil mass never incorporates, or binds w/ the new soil, and it becomes hydrophobic first.

    Due to the difference in compaction between the two soils, the new soil absorbs water more readily; while leaving the old soil dry. To make things worse, if you don't tease the roots of the plant before transplanting, often times they won't grow into, and populate the new soil; which usually ends w/ a dead plant.

    If it's been 3-5 months since transplanting, try brushing a bit of the top soil away & lightly pull up on the plant. If you can still clearly see the dividing line between the old soil, and the new soil, then they probably haven't "combined" to make an even, biologically active soil mass.

    Yes, plugging the drainage holes might work.


  • four (9B near 9a)

    The path could be at the circumference.
    Build a rim dam of absorbent medium, to keep most of the water away from
    the circumference at the top.

    Poke holes, as was suggested; small, to avoid /minimize root damage; many.

    No dam needed for watering at a fast drip / slow trickle rate.
    I either leave the hose in the pot, or
    set my trickler jugs into it --- milk /bleach jugs suitably perforated.

  • Andi C

    i moved some of the soil around the circumference and also the top 2-3 inches after watering. even after dumping 2L of water into the 10g container, the top 1 inch was wet, but then everything below was dry. The roots below the 1st inch were matted with roots and dry. I disrupted the earth at the edges, and top 2-3 inches, and tried to use a bamboo stick to make holes - it ended up breaking because the roots were so dense.

    what can i do to prevent this from happening?

    should i root prune the 10g plants (wax jambu)?

  • halocline

    Picture please.


  • fidgety

    "BTW - Kyodama LOOKS like Haydite. Do you have a link that definitively tells us what Kyodama is made of?"

    Hello Al, thanks for your reply. I'm quite happy to adjust my mix and work with what I can get locally. I have not been able to find out what Kyodama is made of, except that it is a byproduct from an industrial process and it's made in the UK (so fewer carbon miles to transport it). Visually it's not quite the same as Haydite, it has black and white particles with pretty much no shades of brown/grey inbetween.

  • Andi C

    here are some photos of the 10g wax jambu. the roots were matted, and when i was moving the soil at the edges, there were encircling roots, which i pruned off. The soil felt very compacted and even breaking it up by hand was difficult.

    i'm going to increase my watering frequency to try to prevent the containers from drying out. i'll probably have to flush it with

    soil before any disruption

    removed top 1 in ch of soil. many matted roots. the color is also darker. in the spring the roots were white.

    watered about 2L, top of soil is damp

    brushed aside 0.25 inches of soil and it is dry already.

    2-3 inches below, the soil remains dry, compact, and with dense roots.

    forgot to take pictures of the canopy, but many of the leaves are yellowing as the plant is finishing a vegetative flush.

  • fidgety

    Thanks! Yes, I wish it stated on the label what it is made from. I will be trialling this to see if it is any good.

  • four (9B near 9a)

    You wrote that you also do 15gal and 25gal containers.
    This 10gal needs one of those.

    Although 25 might seem to be the clear preference,
    an alternative would be a 15 and my stacked pot technique :
    I make a deep bowl of medium in the 15;
    cut off the bottom of the 10 pot;
    set intact 10 pot+plant into bowl, half of 10 higher than 15 rim;
    add and pack medium around 10 pot;
    slide 10 pot (not plant) upwards a bit, to expose more roots to medium;
    if needed, jam long stablizer poles INSIDE edge of 10.

    Purpose /result is much more (mostly deerper) medium
    without a humongous pot.

  • Andi C

    i can't move the wax Jambu above 10g because they need to winter indoors. this is turning out to be quite a problem

  • four (9B near 9a)

    Meant to be seen /enjoyed, or simply protected?
    If the latter, then It can be diagonal during winter..

  • halocline

    Andi - I just did a little reading on the "Wax Jambu" (I'd never heard of it), and it sound's like they can be kept in smaller pots (even Bonsai).

    "Wax Jambu is a medium sized tree but can easily be kept at a smaller height with a little pruning."

    So maybe do a bit of research on WJ root pruning, and you could put it in a more manageable sized pot.

    Edit: This is a tropical plant, so it can't be overwintered outside.


  • halocline

    four - Picture please.


  • four (9B near 9a)

    Uploading of photo results in nothing but a permanent
    activity indicator, animated circle.

  • halocline

    Yeah, that happens sometimes. When it happens to me; I'll backspace and then try the "Houzz Photo" option (or vise versa).

    If that doesn't work; I just say #%@!!&%#$@!!, and try again later. :-)


  • Andi C

    thanks for the tips. i poked some holes using a bamboo stick and increased watering. Now when i water, i see air bubbles come up and the soil seems evenly wet. thanks everyone!

  • halocline

    Air bubbles are good. That means the water is pushing the old air out, and pulling new oxygen in behind it (gas exchange).


  • halocline

    I found a Surfactant that isn't a multi-function product. ("Revive Organic Soil Treatment")

    How it work's: https://www.revive.com/how-revive-works


  • myermike_1micha

    Rob, you are very helpful around here. I enjoy reading what you have to say.

    All my friends, I pray you are all doing well. I am ok. Just taking care of Mom and Dad.

    Al, thanks a million for stopping by that thread.

    Anyone else finding that summer is quickly passing by? I have yet to hit 90 again since weeks ago. Today was 65, yesterday 55, the day before 60's..What gives?


  • mesembs

    Mike- must be global cooling.

  • halocline

    Thank you Mike; for your acknowledgment. I enjoy sharing my experience, and what I've learned with others.


  • halocline

    Amazon has FP 9-3-6 for $18.29/Quart.

    Cheapest I've ever seen it!



    tapla thanked halocline

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