Container Soils - Water Movement and Retention XVI

December 18, 2012

I first posted this thread back in March of '05. Fifteen 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?size>color>

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 & Retentionsize>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 (partially composted fines are best)
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)

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 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 XV

Post XIV


Post XII

Post XI

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

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.


Comments (164)

  • sharonrossy

    Al, thanks for the encouragement. I'm going to need it! You've done a lot to alleviate my anxieties. I do have another question regarding pest control and any diseases which is a bit off topic. I remember reading about spraying early and alternating the spraying between insect control and fungus blight etc. but I cant find the post. Any thoughts and recommendations?

  • PRO

    It's in my best interest to be encouraging because I like to be around enthusiastic people. ;-)

    I'll leave the control issues up to you. A lot of growers use chlorothalonil (brand names include Bravo, Echo, and Daconil), maneb, or mancozeb fungicides prophylactically to guard against blight and septoria leaf spot (easier to prevent than cure). When it comes to bugs, you should get them identified and choose the least noxious remedy that will eliminate the specific pest or reduce their numbers to something you can live with.


  • sharonrossy

    I'll take that as a compliment! Thanks, Al. You'll be hearing from me soon, of that I'm sure.

    I'll leave my questions on seedlings on another forum!

    Thanks, you're the best,

  • wndy_gardenweb

    Laura -- thanks for the info on the screens!

    Al - three weeks ago I posted that I was going to properly plant my ficus cutting in medium instead of the water it was sitting in. At the time it had a few water roots, maybe 1" long? I think it took make a month to get those roots? Anyhow...

    The ficus cutting has been in a 1.5 cup size cylindrical container of "gritty-mix inspired" medium, not tented, but in the midst of lots of other plants. It was planted maybe 1" to 1.5" deep. The container is resting on big chunks of bark which are inside a bigger container, and the cloth wick from the small container touches the bark (I figured this would help with wicking).

    anyhow, three weeks later... there is a one inch root coming out the bottom! I hadn't even realized that three weeks had past! The root looks like a water root, which I think is because the bark area has water on the bottom. Anyhow, I am just shocked how quickly all this has happened--especially since the poor thing already spent energy on water roots.

    Now I need to figure out when to pot it up....

    Thanks again Al!

  • PRO

    I'll be leaving for a little vacation tomo - doubt if I'll have an opportunity to get to a puter. There are lots of folks here who can answer all your questions though - just wanted to give you a heads-up.


  • sharonrossy

    Thanks Al. I appreciate your letting me know. If I get desperate, I'll start a thread or something. Anyways at this stage, I'm just keeping an eye on my seedlings! Have a great vacation.


  • Loveplants2 8b Virginia Beach, Virginia

    Hi Wndy,

    Glad to help!!

    I also like to see pictures when we speak of containers , mixes and particle size. It is important to post pics and i appreciate your kindness. If you ever have any questions, please ask. I always like to help!! ;-)

    Hi Josh!! I hope you had a great Easter!! Hope all is well with you and yours in CA!!

    Happy growing to you...

    Hi AL.. Glad to hear you and your family had a wonderful Easter too! Have a great vacation!!

    Take care,


  • filix

    I'm still making these soils after so many years. Thanks Al. I hope you have a nice vacation. filix.

  • sharonrossy

    Need some help from anyone. I know Al is away. I have been searching for pine bark fines in the Montreal area. Nothing. Here's what I have found so far:
    1. Medium Pine bark - but the bag is not see thru so I cannot determine except by feel the size. They feel bigger than 1/2".
    2. Cacoa shell mulch
    3. Hemlock mulch
    4. Pine bark nuggets (again not visible and I'm thinking this is what I need)
    5. Cedar mulch
    6. ProMix BX with Mycrorrizae - 75% peat, perlite, vermiculite and dolomitic and calcite limestone with mycorrizae.
    7. Fafard has a container mix - Coconut fiber, peat moss,and biosol compost.

    I would greatly appreciate any feedback or help here. As I said, the pine nuggets and medium bark were not visible unless I ripped open a bag, which I wasnt' willing to do.By feel the nuggets might be a good bet. The hemlock seemed better, again not sure.

    Thanks, Sharon

  • sharonrossy

    Question about the perlite - is there a size I should be looking for?

  • Ohiofem

    Hi Sharon. I don't want to discourage you, but I don't think any of the 7 choices you list as a replacement for pine fines is going to work. It is important to use pine or fir bark in a size smaller than 1/2 inch. Sometimes you'll find small pine nuggets that work, especially if they are composted, but most of it is 1 inch or bigger. I don't know much about hemlock or cedar, but the hemlock and cedar mulch I've seen is in shreds, which won't work. Cocoa shells and coconut fiber are definitely out because they behave very differently than bark. And Promix and Fafard potting mixes are mostly peat. Since you are going to need a cubic yard, maybe you could contact some landscaping companies to see if they can get it for you in bulk.

    As for the perlite, you want the coarsest stuff you can buy. In the states, the bigger bags (4 cubic feet) are much cheaper than the little bags.

  • sharonrossy

    Thanks for the tip. Someone mentioned that hemlock would work if its the right size. I'm going to have to check it out. What else do you suggest I use? I'm getting discouraged. Most of what I'm finding is either really shredded or large pieces. We have Home Depot here and they will order pine bark but their description of the product doesn't indicate what size the pieces are.
    For the perlite hopefully that shouldn't be a problem. I have a couple of other landscaping sources to check out. Guess I might have to poke a small hole in a few bags. Any help would be really appreciated.
    Thanks, Sharon

  • Loveplants2 8b Virginia Beach, Virginia

    Hey Dave.

    Wanted to bump this for you !

    Have fun with this info!

    Thanks AL!

    Take Care,


  • verde617

    Hello Al / All,

    Thank you Al for responding to my email. Very helpful.

    Next set of questions:

    Is there any container plant that shouldn't be grown in the gritty mix? I'm working on citrus, figs, herbs, bamboo, birds of paradise, and the odd flowering shrub or two.

    Also, I'm aiming for particles between 1/4" and 1/8", correct? So a 1/4" screen should work, yes?

    Apologies in advance if this has already been addressed.

    Joe V

    PS---fellow Lo-CaLers: Turface is available at
    6160 Marindustry Dr
    San Diego CA
    (800) 552-8873

  • edweather USDA 9a, HZ 9, Sunset 28

    1/4" to 1/8" is correct for the gritty mix, so a 1/4" screen will work. But you also don't want any powder in it, so I used a 1/8" screen also.

  • jodik_gw


    Grown in my own rendition of the Gritty Mix... slightly correcting for a teeny bit more moisture retention...

    Mike, this one's for you! :-)


  • flashAU

    I started reading GW because I have an avocado that desperately needs to be re-potted. After reading some of those threads, I stumbled upon this one and have been fascinated by things I had no clue about. Anyway, I decided to make the gritty mix and have been searching for the ingredients. I did find a soil conditioner that I think is the pine bark fines and I found some Poultry Grit by Manna Pro. There may be a place that has the Turface, but they're closed today, so I don't know for sure on that one. Anyway, I think I read that there is some DE sold by Napa that can be substituted for the Turface. Is this correct? I am really looking forward to trying this mix. Any help will be appreciated.

  • flashAU

    Here's some pictures of my pine bark fines. I screened using a pond basket (thanks Josh) to get the dust out. I still need to get the sapwood out.

    I haven't figured out how to put more than one pic on her or I would seek advice as to what to do with my avocado. Maybe another post in another thread.

  • Ohiofem

    Just took this photo to take to the NAPA store so I can buy more. They often try to tell me it doesn't exist, or try to sell me oil dry, which is not the same. I love this stuff. It is a little more water retentive than Turface or perlite.

  • flashAU

    Thanks Ohio. Do I need to add the gypsum if I use the Floor-Dry?

  • PRO

    Whether or not you need gypsum (and Epsom salts) depends on whether or not the fertilizer you're using has Ca (and Mg). If your fertilizer lacks Ca, add 2-3 tsp of gypsum/gallon of soil when you make it. If your fertilizer lacks Mg, use 1/8-1/4 tsp of Epsom salts added to your fertilizer solution every time you fertilize. Easiest is to use a complete fertilizer that also has all the secondary macros and all the micros in an appropriate ratio. I prefer a 3:1:2 RATIO fertilizer (RATIO is different than NPK %s. 24-8-16, 12-4-8, and 9-3-6 are all 3:1:2 ratio fertilizers. Foliage-Pro 9-3-6 has all the essential nutrients (including Ca/Mg) in a ratio appropriate for almost all plants. It's essentially all I use as my 'go to' fertilizer.


  • flashAU

    I fjound the Turface at a john Deere store and the "soil conditioner" at a local nursery. There is a stone and sand place that sells something called #89 grainite. I bought three 5-gallon buckets and screened using 1/4" screen and insect screen. Will this suffice? They also sell crushed limestone, but I due to pH concerns, I thought the granite would be better.


  • PRO

    The granite should be in a size range from 3/32-3/16 for best results. Gran-I-Grit in grower size, #2 cherrystone, and Mana Pro in poultry size all work very well.


  • sharonrossy

    Al, not to be redundant, but I finally found the pine bark necessary for the 511 mix.Of course our weather has been really dreadful, but in any event, I have a couple of questions. For the fertilizing, do you still recommend adding a slow release fertilizer when planting and should I add Epsom Salts or not necessary? I have everything, just waiting for the weather to clear up and be safe for the tomatoes. It's Montreal, we never know one minute to the next what the weather will be.
    Thanks, Sharon

  • sharonrossy

    Al, not to be redundant, but I finally found the pine bark necessary for the 511 mix.Of course our weather has been really dreadful, but in any event, I have a couple of questions. For the fertilizing, do you still recommend adding a slow release fertilizer when planting and should I add Epsom Salts or not necessary? I have everything, just waiting for the weather to clear up and be safe for the tomatoes. It's Montreal, we never know one minute to the next what the weather will be.
    Thanks, Sharon

  • sharonrossy

    Al, not to be redundant, but I finally found the pine bark necessary for the 511 mix.Of course our weather has been really dreadful, but in any event, I have a couple of questions. For the fertilizing, do you still recommend adding a slow release fertilizer when planting and should I add Epsom Salts or not necessary? I have everything, just waiting for the weather to clear up and be safe for the tomatoes. It's Montreal, we never know one minute to the next what the weather will be.
    Thanks, Sharon

  • cameracassidy

    I've been using the gritty mix for succulents indoors. I've checked to make sure I don't have a perched water table but using a toothpick in the bottom of the pot after it stops draining. Nothing drips out so I assume I'm good as far as that goes.

    How often can/should I be watering? I was watering once a week but my plants seem to be suffering a little. I generally tend to over water so I wanted to check with the experts before I water more. Thanks for your help!

    Here is a link that might be useful: Succulents and Sunshine

  • greentoe357

    Al and others, thank you for years worth of very useful info in this thread. I am a total newbie and just went through 5 or so of the 16 sub-threads over several days. Some questions recur and answers are difficult to find in all these screens. Perhaps a FAQ that includes details on each ingredient would simplify things for active responders (no need to repeat) and those looking for answers like me. FAQ should probably include sizes of the ingredients, names they can go by, substitutions if you can't find it, best pictures, and brand names. Maybe some general advice on variations of the mix depending on what people are growing; how often they want to water, how big the container is etc. Anyway, just a thought.

    My question is : how long can I store my 5-1-1 mix with lime and fertilizer mixed in? I am afraid the fertilizer granules will start leaching if stored mixed into the soil. I have relatively small quantity of plants and am still building my collection, so there is a very good chance that I'll need the mix again and again this season and can definitely use it next season if I can store the mix. It will be stored indoors. I prefer not to mix it every time when needed in order to minimize the mess. Maybe I can mix only what can be stored for some months and then just add fertilizer or whichever components start degrading sooner? What do you guys recommend? Thanks.

    This post was edited by greentoe357 on Thu, May 30, 13 at 4:41

  • Ohiofem

    I mix my ingredients in a fairly dry state and have not worried about the lime or Osmocote Plus breaking down while in storage. Both are pelletized and require water to be activated. I make 25 gallons of mix at a time in a compost tumbler. If I added water to the mix, I wouldn't be able to turn the tumbler. I add the water when filling the pots. If I have time, I let the pots with wet soil sit for several days after watering to allow the ingredients to begin working. Sometimes -- like when I am potting up a plant whose pot has broken -- I don't wait.

    You could wait to add the lime and fertilizer to the other ingredients until just before using the mix if you want to be especially careful. I stored a 30-gallon garbage can of completed 5-1-1 mix in my garage over the winter and saw no problems develop in the plants I used it on this spring. I've done the same things with store-bought potting mixes that have a fertilizer charge.

  • PRO

    Sharonie - you prolly don't need Epsom salts at all in the first year of using a particular measure of soil if you used dolomite. If you push the soil to a second year of service, some Mg supplementation might be necessary because the Mg is much more soluble than the Ca fraction of dolomite. GOOD LUCK!!! ;-)

    Cameracassidy - If you made the gritty mix correctly, it will be hard to over-water even succulents ...... but still, it's best not to tempt fate. If your pot is deep and the root mass shallow, you might need to water every other day until the roots colonize the soil. I regularly leave cacti/succulents out in even shallow puts during periods of extended rainy, wet weather with no root issues.

    If you're worried about over-watering, why not use a wick or tilt the pot and water more often until you're sure the roots have found a home deep in the pot?



  • Ohiofem

    Great illustration, Al. I hope you're going to continue this topic for a 17th round. It is such a valuable service. I wish GW had sticky threads.

  • PRO

    I have lots of sticky threads at a competing forum site. There, they make them a sticky if one or two members other than the original poster make the request that they be pinned to the top of the forum. Not sure why they don't do that here ..... maybe if enough people requested it? I do intend to continue the thread when it tops out. It's been soo much fun, and I've met soo many interesting people through my participation here. I haven't been around as much as I usually am lately. I get a lot of mail off forum that I try to answer, and I've been really busy with work and my own garden/bonsai projects this spring. I read more than I post, and everyone has been giving such good advice lately that I don't have as much opportunity to join the exchanges. For the most part, we're pretty much all on the same page.


  • Loveplants2 8b Virginia Beach, Virginia

    Hi Guys!

    I agree. This needs to be at the top of the forum since it is the most informative thread for all levels of growers! I always find people asking me questions through emails and I like to send them here or send them the link .

    Great information Al. Thank you!!

    I will let them know my thoughts on the sticky idea!!!

    Hope you are having a wonderful summer!!! ;-)

    Take care,


    This post was edited by loveplants2 on Thu, Jun 6, 13 at 22:12

  • Loveplants2 8b Virginia Beach, Virginia


    Get ready, Al...

    It's getting close!!!

    Thanks for all you do!!


  • PRO

    Thanks for the reminder, Laura.


  • PRO

    Now is a good time to jump in and leave a link to the new thread. Thank you, and everyone else for helping to get the word out to more & more growers. I can see it's making a difference!

    You can find this thread continued here.


    Here is a link that might be useful: New thread

  • nakenge12

    I have a question. I'm very new to this but I just wanted to know, are the 511 and gritty mix non-soil putting mixes? Because it looks like it from the recipe. I'm new like I just potted my first plant yesterday.

  • Ohiofem

    Yes. They are non-soil potting mixes.

  • nakenge12

    Thank you for answering. I was getting a headache trying to figure out why I didn't see soil in the ingredients list for soil mixture. I thought it was a given, like it was assumed everyone knew to put in soil. That cleared up a big part of my confusion.

  • nakenge12

    Also, is the 511 a good mix for Anything or do you have to be more specific for other things? Like vegetables, fruit trees, and herbs?

  • Ohiofem

    People talk about potting soil in general even when it doesn't include soil. Very few experienced growers are in favor of including soil in a container.

  • Ohiofem

    5-1-1 works for everything I've tried it with including vegetables, flowers, herbs, house plants and trees.

  • greenman28 NorCal 7b/8a

    Ohio is right! Both of these mixes are incredibly versatile because they can be tailored to your particular gardening situation. 5-1-1 is wonderful for outdoor Summer vegetables, but can also be modified for indoor Hoyas or jungle cacti.


  • nakenge12

    Thank you both very very much

  • nakenge12

    Another question. What's good for repelling ants? The first day it warmed up here I noticed several of them and I can only assume it will be worst because I've only lived here for two months.

  • Ohiofem

    This is a very old discussion that few people are following. It also is focused on growing in containers where ants are rarely a problem. It's generally better to start a new thread when you have a new topic. You are likely to get more feedback if you post this question as a new one on the Vegetable Growing Forum:


  • PRO

    Now is a good time to jump in and leave a
    link to the new thread. Thank you, and everyone else for helping to get
    the word out to more & more growers. I can see it's making a

    You can find this thread if you click me!


    Here is a link that might be useful: It takes you to the most recent thread.


  • Sergey Varlamov

    Hi Al and others,

    I would appreciate advice on saving sick/dying Picea glauca, in pic.1, please. I bought it on post Xmas sale and it was ~50cm tall, looking healthy, with very bushy top. I repotted it without much root cleaning to keep most original soil with fungus, which I read Picea, like other pines, needs. I planted the rootball with old soil into gritty mix, mostly pine bark fines with seramice, with a bit of gravel, see in pic.2 very "gritty" indeed :); trunk is ~1/2" at the bottom). I used a biggish pot to let it grow freely for a year or two. I also cut the top to encourage lower branches growth but it never happened. Water it when the pot feels light, ~ weekly (it is early autumn here in Sydney) by bottom watering in a bucket, then drain well by keeping the pot at ~45 degrees for a while. Use diluted Nitrosol liquid plant food every two weeks. Keep it on sun for 2-3 hrs, then half shade.

    Despite all my care (or coz of it ? :), the picea never showed any new growth but started developing warning signs for last 2-3 weeks. Those few thin branches started dying. Their stem turns from brown to greyish-green and gets soggy before dying. See in pic 3&4, that branch in front which is dying now, with grey stem. Other branch died a few days ago. Only three normally looking branches are left. But I am afraid they are facing same fate.

    Anything I can do to rescue my future picea bonsai at all? Thanks and cheers, Sergey

  • Diego Romero

    Hellow buddy, this is the best topic ive everr seen about soil in my life. Thank you indeed! Any problema addint you on facebook ? I am gret student of plants / soil , etc. I made some experiemnts all turned for succulents and cacti. Do you have some to share about this kind of soils / plants ? Thanks a lot man, keep rolling.

    tapla thanked Diego Romero
  • PRO

    ..... no longer monitoring this post. Most recent continuation of the thread can be found here: https://forums2.gardenweb.com/discussions/2842847/container-soils-water-movement-and-retention?n=8

Need help with an existing Houzz order? Call 1-800-368-4268