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Container Soils - Water Movement and Retention XVIII

tapla
6 years ago

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

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

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

Is Soil X a 'Good' Soil?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, dust - 3/8 (size is important
1 part sphagnum peat (not reed or sedge peat please)
1-2 parts perlite (coarse, if you can get it)
garden lime (or gypsum in some cases)
controlled release fertilizer (if preferred)

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

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

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

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

The gritty mix:

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

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

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

Post XVII

Post XVI

Post XV

Post XIV

Post XIII


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

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

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

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

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

Al

Comments (225)

  • wisconsitom
    4 years ago

    At considerable risk of said throat-jumping-downing, I'll add in a personal perspective: I've grown large containers of ornamental plants for decades now, not just for the hell of it but as a part of my occupation as a pro horticulturist. Now-gasp-we have always used native soil as a part of our mix! So what gives with this guy showing up here and seemingly refuting a giant and apparently learned thread? Very simple-these were annual plantings! Nothing had to survive, let alone thrive, after roughly mid-October. That is to say, I agree completely with all of Al's recommendations......if..........we're talking perennial or long-term plantings in containers. But for those things which are only to last the one growing season, the decay and subsequent collapse of organic matter, as well as a host of other issues adequately and properly addressed via the 5/1/1 thing lose significance, at least here in a northern clime. Perhaps in Florida or some place where near-every containerized planting can rightfully be expected to be a long-term project, all of these factors take on significance. But not in Wisconsin, in a container full of plants which will be dead at first freeze!

    +om

  • rooftopbklyn (zone 7a)
    4 years ago
    last modified: 4 years ago

    5-1-1 is intended for annuals, not long term plantings. It is also intended to be easy to make, requiring no sifting once correct ingredients are found. However, it can be difficult to source in some places, but most people who persevere find ingredients relatively close to home.

    EDIT:

    also, the concerns raised (primarily PWT and it's effect on roots/growth/vitality) apply to any plant in a container, even ones that only live a single season.

    Daniel

    tapla thanked rooftopbklyn (zone 7a)
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  • ethanqsimmons
    4 years ago

    How necessary is the sifting process? What are the repercussions of not sifting?

  • ethanqsimmons
    4 years ago

    Also, which Napa floor dry should be used? It looks like they have a diatomaceous earth formula as well as a montmorillinite clay formula.

  • Ohiofem
    4 years ago

    Sifting is pretty important for the bark in the gritty mix to keep out pieces larger than 3/8 inch and dust under 1/16 inch. It is also advised for removing dust from granite grit, floor dry and Turface. In my opinion you don't need to sift the ingredients for 5-1-1 unless your bark has pieces larger than about 1/2 inch in diameter.


    I've used the NAPA Floor Dry that is made of Diatomaceous Earth, part number 8822.


    tapla thanked Ohiofem
  • four (9B near 9a)
    4 years ago

    All important factors taken into account, Napa 8822 is best ingredient
    to use for that role in a mix.

  • rooftopbklyn (zone 7a)
    4 years ago

    Four,

    Can you explain further? Which factors, and how is it better than turface? Have you worked with both? I am curious, as I've only ever used turface but can obtain Napa 8822 more conveniently than turface.

    Daniel

  • wisconsitom
    4 years ago

    Yes Daniel, but I'm not talking about failure. I'm talking about exuberant growth that knocks people's socks off, I'm talking about a proven methodology that-I will repeat myself-has worked for decades. My "mix" is a combo of leaf compost, native soil, and some volcanic rock that was added by my predecessor to reduce weight of these large planters. So I will agree to disagree, based again on the fact that what I've been doing since 1990 has not merely worked, it has been wildly successful.

    +oM

  • jodik_gw
    4 years ago

    Based upon the laws of physics, and so much more information and knowledge I wish I'd had access to as young grower just beginning my journey, Al, I have once again copied and pasted your articles to the desktop of my new laptop for easy access to reference.

    Having a clear understanding of the concepts involved, I am on track toward optimal genetic potential of those plants which I confine to containerized spaces... and I want to thank you yet again for generously sharing your insight, your knowledge, and conveying the science, the how and why, in laymen's terms that are easy to understand.

    Once one takes industry standards, convenience, fallacy, opinion and personal experience off the table as absolutes (which they are assuredly not)... and begins the journey of eliminating obvious limitations through knowledge, one actually begins to see the differences that occur.

    Success is a relative term... what one person is happy with could be considered failure by someone who measures success differently.

    I really do wish Houzz would consider this collection of concepts, recipes and knowledge important enough to permanently paste at the top of this Forum. It has proven itself worthy, and has stood the test of time and usefulness.

    If only more people realized that a "green thumb" is nothing more than applied knowledge.


    tapla thanked jodik_gw
  • wisconsitom
    4 years ago

    Heh, this is getting ridiculous. I like Al's treatment of the subject, but again, "my definition" of success is success, plain and simple. I'm not the guy who goes around smelling the flowers, or oohing and aahing...that's what the people visiting or living in this city do. For gawds sake, I'm all for science-based practice, but a part of science is realizing there's more than one route to success. Wow.

    My only failing here is in not having photos to show you, jodik. I can assure "what one person is happy with" in this case is not something that anyone would call failure. Just wow.

    +oM

  • drew51 SE MI Z5b/6a
    4 years ago

    I think many better ways exist to take care of plants. i find the info somewhat useful, but one must remember that soilless mixes were developed because of the weight problem in shipping. Many organic mixes work as well or even better. Movement in the industry is actually away from soilless mixes. I myself feel each plant group has different needs. Feeding all people solent green doesn't work, and one method to care for all plants certainly will never work. Also it's nice Al called it 5-1-1 and gritty, but these type of mixes have been around since the 1970's. It's nothing new that's for sure. We used to call gritty mixes mineral mixes. And 5-1-1 is a soilless mix. Many companies like Fafard have been selling 5-1-1 type mixes for decades. I first used a gritty mix in 1975.

    I have since moved on...

  • rooftopbklyn (zone 7a)
    4 years ago

    Tom,

    First, I did not use the word failure, or make a single judgement about how you grow. Not sure where you got that from. I simply stated facts, which is that water sitting in the bottom of a container IS detrimental. Maybe you disagree with that - if so, then there isn't much point in continuing to discuss.

    Will you accept that even with your explosive growth that makes you and observers impressed and happy, there is a possibility that growth could be better if some things were changed?

    I do understand that you have a method that works for you with an effort you're comfortable with, and no one is trying to tell you to change. This is a choice every grower gets to make.

    However, we are trying to educate people on limitations faced by plants in containers and how to remove them - so each person can make their own choices. Your messages seem to imply that it's not worthwhile for annuals, and I don't think you can back that up - especially if you haven't even tried the suggestions made herein.

    Daniel


    tapla thanked rooftopbklyn (zone 7a)
  • wisconsitom
    4 years ago

    As part of education, it is important to not slip into dogma. As much as I and everyone else admires the work of Al on this board-and heck, he's famous elsewhere too!- it would be exactly that-a disservice-to any prospective reader, to get the idea that there is but one way. BTW, where did I say it's OK for water to sit in the bottom of the container?

    There is virtually no chance the container work I do could be "better". That's a subjective term anyway, but i would guess that out of any random sampling of 100 people, there would be exactly zero that would find fault in any way.

    Al's own words support my statement that this is less a matter of import in annual plantings. The subsequent decay of organic material just doesn't matter within this time frame in this part of the country. And I allowed for differing results where growing seasons are longer, so any attack from that direction is pointless. Furthermore, water easily moves through these planters. There's just no angle from which you can disparage the results so obtained, using nothing more than good compost and filed soil.

    I worked in greenhouses long ago and of course no field soil is used in such production these days. But-and this is significant-one good hot weekend with nobody on hand to provide water would do in most potted materials at such businesses. Same would hold true for us if we had nothing but light and fast-draining media. The compromise between the varying factors is what makes this-or any-system work. If all one did was go for drainage, they would go too far in that direction. If all one did was go for water retention, same thing. But by balancing these factors,which is exactly what happens in our system, even three-day weekends are manageable. I'd wager that your experience is insignificant compared to my own. You are waving your arms around-look how smart you are-but I'm simply telling you and all readers, this method is not the only way. Because it's not.

    +om

  • rooftopbklyn (zone 7a)
    4 years ago
    last modified: 4 years ago

    Your experience is unquestionably longer and more complete than my own. I do agree that finding the correct compromise for their own situation is and should be everyone's goal, and that there's likely many different ways to achieve this.

    It's telling that you find no room for improvement in your methods.

    Daniel

    tapla thanked rooftopbklyn (zone 7a)
  • tapla
    4 years ago
    last modified: 4 years ago

    What we discuss here is not a method, and nothing is carved in stone - ever. We discuss a concept that has the potential to give every/any grower more control over their growing experience. I don't know what's buggin' you, Tom, but no one ever said, implied, or suggested there is only one way, and no one twists anyone's arm to do anything other than exactly what they want to do. The emphasis is always on helping people understand how water behaves in container media and how to eliminate the limitations associated with excess volumes of water, which is a huge problem that impacts a very large fraction of growers using commercially prepared media. With that understanding, they are intelligently able to determine what compromises are appropriate for their individual application. IOW, they learn how to take control of their plant's vitality rather than resign themselves to limitations associated with excess water retention. There are even threads devoted solely to dealing with excess water retention w/o having to touch a particle of bark, perlite, Turface, grit, calcined DE ......., so what's with the tirades/ huge chip on the shoulder? You haven't said anything new - anything that hasn't been discussed a hundred times over. You'd know that had you taken some time to look things over before you started jumping on everyone with both feet.

    Many hundreds of growers, if not thousands (probably more accurate) have offered testimony on this thread and many, many others about how an understanding of water dynamics in container media has turned their growing experience completely around. That's the part I'm interested in; I don't care about the guy who's already perfect and suggests there is no chance that his results could possibly be anything other than the manifestation of perfection itself. ("There is virtually no chance the container work I do could be "better".") You got me there. I KNOW there will always be room for improvement in anything I do - no matter how hard I try.

    Al

  • Ohiofem
    4 years ago

    One tell tale sign of the people who come to this thread with the main motive of wanting to start a fight is something very much like what you said in your first post here wisconsitom, when you predicted that "someone will take the opportunity to attempt to jump down my throat." The argument that is always made by folks who want to pick a fight is that those of us who praise 5-1-1 and/or gritty mix are claiming that one size fits all and will viciously attack anyone who says otherwise. I've it heard dozens of times on this thread and in this forum over the past five years, and it's just a waste of everyone's time.

    If you have a formula for a wildly successful container mix incorporating "a combo of leaf compost, native soil, and some volcanic rock," please start a new thread describing it in detail. I promise you many people will want to hear about it and most won't even argue with you.

    tapla thanked Ohiofem
  • four (9B near 9a)
    4 years ago

    Tom should be made to feel welcome here.
    Nobody had to get into sparring with him.
    When the sparring was in progress, I was about to write simply
    "Quit it, you two."


  • Ohiofem
    4 years ago

    Everyone who has ideas to share and questions to explore is welcome here. I was sincere in asking Tom and anyone else who has ideas about a superior potting mix to tell us the details.

    tapla thanked Ohiofem
  • ewwmayo
    4 years ago

    Honestly, my first mistake using gritty mix was assuming that 1:1:1 (turface/bark/grit) would be great and 'the solution' for my plants/succulents.

    I had read all XVIII and many more threads going several years back. I thought I understood it and everything seemed to make sense.

    But I didn't really understand that this 'recipe' for gritty mix was only the very first step in the right direction.

    My first two batches of gritty mix were a failure and I ended up repotting all my plants after just one month. After that, I made sure I sifted well and started to customize my component ratios for each plant/species I grew.

    Only after spending a huge amount of time learning, experimenting, measuring, and recording my results did it start to make sense. And then I started to get really good results.

    To me, Gritty Mix is just a general term for a somewhat chunky growing substrate. Over in the Cacti & Succulent forum (where I enjoy hanging out), it seems like every experienced and successful grower is using a different mix.

    And it's quite enjoyable to discuss the merits and reasoning behind their choices. My summer rooftop growing conditions are pretty unusual for Zone 6a and truthfully more like California.

    Who knows! I'm pretty new to this, but I'm happily using most of the tools/dataloggers used in commercial greenhouse operations and always doing my best to learn as much as possible. =)

    tapla thanked ewwmayo
  • pip313
    4 years ago

    Al has stated that it's a basic formula that you can tweak. The important idea is the concept.


    that being said, and keep in mind I mainly just grow citrus, after 20 plants and 200 gallons of the regular mix, I'm liking it. It's only been a month but they seem to respond well and I know I had issues with regular peat mix.

    tapla thanked pip313
  • wisconsitom
    4 years ago

    Forgive me for skipping past some recent posts here-I actually have work to do, lol, but let me just say, nobody, not Al, not rooftop, nobody...wants to have their truthfulness questioned. That is what happened to me when I made some additions to this giant thread-my veracity was put into doubt. That is hugely offensive. I have no horse in this race and as in the numerous other Houzz boards, on many of which I'm a much more prominent member, there is simply no other agenda than sharing-and possibly attempting to showcase another facet-of whatever is being discussed. Granted, most of you don't know me from Adam, but again, any person does not want to have doubt cast on their truthfulness or for that matter, their judgement.

    Again, when I said the container work I do is of exceptional quality, that is exactly what I meant. Any attempts to parse these words, to find hidden meaning, is at best a waste of our time and at worst, very insulting. I'm sorry for upsetting the apple cart you guys have going here. Proceed. You have obviously no need for questioning of anything.

    +oM

  • four (9B near 9a)
    4 years ago


    > "skipping past some recent posts"


    Do read them.

  • ethanqsimmons
    4 years ago

    Are 1/4" granite particles acceptable for the gritty mix? And has anyone tried the 5:1:1 mix using coconut coir? If you did use coir, what kind of results did you see?

  • ethanqsimmons
    4 years ago

    Also, are there any other substitute materials for granite besides cherrystone?

  • halocline
    4 years ago

    Expanded Shale (Haydite). Why?

    Rob

  • rooftopbklyn (zone 7a)
    4 years ago
    last modified: 4 years ago

    You can search the container gardening forum for "coir" and find MANY discussions, or you can just go to the top of this particular post and search with your browser's built in search (search of the webpage on the screen, not google) and find a number of thoughts about it on this very page.

    In short - folks who generally subscribe to the principles discussed here and who have tried coir in 5-1-1, find it inferior to peat. For details, search as recommended above.


    tapla thanked rooftopbklyn (zone 7a)
  • ethanqsimmons
    4 years ago

    Thank you both for your replies! I asked about substitutes for granite in case my local landscaping place doesn't have granite in the right size. As for the coir, I would really like to avoid using peat due to the environmental impact that it has. Are there any other alternatives to peat?

  • pip313
    4 years ago

    Shipping coir isn't environmentally friendly either. Nor is using massive amounts of water to flush the salt out.

  • pip313
    4 years ago

    As far as granite, farm supply stores are the best place to get it.

  • Ohiofem
    4 years ago

    I've researched the controversy about the environmental impact of harvesting peat moss and concluded that the Canadian peat industry is a responsible steward of this huge and renewable resource. If you are interested in their side of the argument, visit http://peatmoss.com. I don't think this is the right place to argue about the question. If you prefer to use a peat substitute, you might look into rice hulls. I tried various forms of coir and had a lot of problems.

    tapla thanked Ohiofem
  • four (9B near 9a)
    4 years ago

    > "any other alternatives to peat?"

    Yes, but environmental consideration is as for peat (use of them creates or increases financial incentive for their destruction).

    Best to adopt the gritty mix practice instead.

  • ethanqsimmons
    4 years ago

    Definitely not trying to start an argument, just curious. I ended up buying peat. Bu can someone please tell me what size of granite is best? My local farm supply stores don't have chicken grit so I'm going to a landscaping store so I need a rock size measurement. Thanks!

  • Ohiofem
    4 years ago
    last modified: 4 years ago

    The granite for gritty mix should be between 3/16 and 3/8 inch in diameter just like the other components of the gritty mix. A possible substitute would be #2 cherry stone.
    I'm curious about why you bought peat if you are wanting to make the gritty mix? Peat (or a substitute) is part of the 5-1-1 mix which doesn't include granite.

    EDIT: As Rooftopbrooklyn pointed out above, many of these questions are answered in this very long thread, including the issue of using coir and the size of the grit. So "go to the top of this particular post and search with your browser's
    built in search (search of the webpage on the screen, not google) and
    find a number of thoughts about it on this very page."

  • ethanqsimmons
    4 years ago

    I'm doing both the 5:1:1 as well as the gritty mix. And I did try searching "granite" and "size" with no luck. Sorry if my questions were repeats.

  • Ohiofem
    4 years ago

    Ethan: I'm sorry if my comment seemed like criticism. I just reviewed the discussion and see that you already considered cherry stone #2. Some people have substituted aquarium gravel. Here's a link to forum search results that should return many discussions about substitutes for grit and size issues: http://www.gardenweb.com/gardenweb/query/Grit/topic=contain

  • ethanqsimmons
    4 years ago

    So I ended up buying some kind of crushed granite from a landscaping store (see attached pic). Do you guys think it will work? Also, I have attached pictures of the bark that I bought. Will the bark with smaller particles (darker one) be suitable for the gritty mix? Will the bark with the larger particles (lighter one) be suitable for the 5:1:1? Thanks everyone!

  • tapla
    4 years ago

    These are copy/pasted from files I keep because the question arises so often:

    Grit Sizes


    Ideal for gritty mix:

    In a perfect world, the mineral fraction for use in the
    gritty mix would range in size from about 1/10 - 5/32" (.100 - .156" or from about 2.5 - 4.0 mm) The
    bark fraction would be slightly larger to allow for some breakdown over the
    life of the planting ........ from 1/8-1/4 is about ideal (.125 - .250" or
    about 3.25 - 6.25 mm)

    starter: 1/16 - 3/32 inch (1.5875 - 2.3813 mm)

    grower: 3/32 - 3/16 inch (2.3813 - 4.7625 mm)

    devoloper: 3/16 - 5/16 (4.7625 - 7.9375 mm)

    turkey: 5/16 - 7/16 inch (7.9375 - 11.1125 mm)

    turkey
    finisher: 7/16 - 5/8 inch (11.1125 - 15-8725 mm)

    My OPINION re peat vs coir or CHCs:

    Peat vs. Coir

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

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

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

    The results were startling. In both cases, the cuttings
    grown in the CHC's exhibited < 1/2 the biomass at summers end as the plants
    in the bark mix.

    I just find it very difficult for a solid case to be made
    (besides "It works for me") for the use of coir or CHC's. They're
    more expensive and more difficult to use effectively. The fact that some
    believe peat is in short supply (no where near true, btw) is easily offset by
    the effect of the carbon footprint of coir in its trek to the US from Sri Lanka
    or other exotic locales.

    That's the view from here. YMMV

    Coir Study: https://sites.google.com/site/plantandsoildigest/usu-crop-physiology-laboratory/coconut-coir-studies




    Peat - Renewable or Not? - Does it Matter?



    Chicken Little would be
    aghast at your inference!! In my estimation, it doesn't matter much if it's
    renewable or not, and I refuse to be made to feel guilty about using any form
    of peat.



    Here is a reply I often leave
    when the non-renewable thing comes up:


    "Sorry, but I'm not buying
    the non-renewable lament. In Canada alone, there are more than 270 million
    acres of harvestable peat bogs. If we make the conservative guess that the
    harvestable portions of these bogs are 10 feet deep, that means there are
    probably more than 900 billion cu. ft. available for harvest, just in Canada!
    That doesn't even take into consideration what's available in Europe, Asia, or
    places like New Zealand where they also mine peat. Canada currently has
    mining/harvesting operations underway on approximately 40 thousand acres or
    about .014% (that reads 14 one thousandths of 1 percent)."



    Check the math - it's
    accurate and conservative. It's more likely that the next ice age will be upon
    us and glaciers will have covered what's available before we even use a noticeable
    percentage.



    Renewable/non-renewable =
    moot.


    Al


  • ethanqsimmons
    4 years ago

    Thanks! I have repotted all of my succulents that were doing poorly in gritty mix, and I'll keep everyone posted on how they do.

  • ethanqsimmons
    4 years ago

    What are the repercussions of using bark that's too big?

  • tapla
    4 years ago

    It varies because it depends on the size of the other components. IOW, if the other components of the soil are appropriate in size, the change in water retention and aeration is fairly insignificant, but it one of the other components is also on the large side, the effect is much more significant.

    Al

  • ethanqsimmons
    4 years ago

    The bark seems to be significantly larger than the other particles. Should I expect issues trying to grow in this mixture? Any way to remedy it without repotting?

  • tapla
    4 years ago

    Here's what I urge: Don't look at making the gritty mix or even finding the ingredients as a necessity. Take a deep breath, organize your thoughts, and proceed at a relaxing pace w/o establishing a time frame. I suggest this because it's frustrating if you don't know where to look or find the ingredients you need, and you're much more likely to make decisions (like using inappropriate materials or sizes of materials) that will sour you on the concept - and that would be very unfortunate.

    Make SURE you understand the concept. When you do, it opens potentialities of using alternate ingredients. Did you let us know where you live?

    Al

  • ethanqsimmons
    4 years ago

    I live in the Bay Area which is Zone 9b. And for what it's worth, here is my attempt to answer my own question about bark being too large (please correct me if I'm wrong): if the bark particles are significantly larger than the other particles in the mix, be they perlite or gravel or peat, the PWT height will be decreased slightly (slightly because, at least in the gritty mix, bark is not the major component). Additionally, the larger bark particles will have less surface area and so gas exchange and nutrient release (organic matter) will occur at a slower rate. How much these factors will be affected by the bark size, I'm not sure, but hopefully it's not detrimental. More frequent fertilization may need to occur in order to compensate for decreased rate of nutrient release from the bark. Also, due to decreased surface area, the bark portion of the mix will retain less water, making the mix very, very quick-draining. Again, I'm hoping this will not be to an extent that the plants are harmed. That's about all I can think of in terms of the impact of large bark particles. I would appreciate any input! And, I have re-read this thread many times, and I've absorbed the concepts as much as I can, so I would appreciate it if I was not told to read the thread again and figure it out on my own. Thanks!

  • ethanqsimmons
    4 years ago

    And if my mix doesn't work, I definitely will not blame it on the gritty mix. Unless I follow the instructions to a "T" I don't think I can say it does or does not work.

  • ewwmayo
    4 years ago

    To help aid your inner dialogue, here are my thoughts:

    1. Bark too big = more empty space. Empty space aids gas exchange but holds no water or nutrients. After a certain point, you just end up with useless (unproductive) voids in your soil.

    2. With certain sized particles, PWT height becomes essentially insignificant. Particles bigger than that do not provide any further PWT advantage.

    3. Too big pieces alone aren't going to kill your plants and you just may not get as productive soil as you could otherwise.

    4. The components you use and ratio of them likely have a bigger impact on CEC (nutrient availability) than slightly bigger pieces of bark.

    One advantage of gritty mix is that changing your mind and mix is not as detrimental to plants as finer mixes and soils. If you do it carefully, you can minimize root damage and only end up setting your plants back several weeks or so in progress (for most healthy plants).

    There's a lot of opportunity to customize your mix and I think if you try different variations you will get a better feeling (and satisfaction) for how different changes in gritty mix affect the root zone/plant care/plant health. Understanding concepts + application of theory = great learning in practice.

  • greenman28 NorCal 7b/8a
    4 years ago

    Ethan,
    large bark causes inconsistent wetting and drying of the mix. The smaller particles will eventually migrate to the bottom of the container, causing compaction, raised perched water layer, lack of aeration and drainage, et cetera. Meanwhile, the upper portion of the container will dry out faster, compromising the roots in that zone, and thus requiring you to water on a strange schedule. Not advisable at all.

    Josh

  • ethanqsimmons
    4 years ago

    Alright, so I've got a sieve with 1/4", 1/8", and 1/16" filters. My question is, for those using GreenAll Micro Bark, what kind of yield are you getting with the 1/4" mesh? I've sifted through half a bag and have a pitiful half gallon or so of stuff, most of which looks to be dust. Is there a good technique to use when sifting?

  • ethanqsimmons
    4 years ago

    If I'm using pine bark fines (uncomposted) instead of a mix of fines and nuggets, would something like 5 parts pine bark fines to 2 or 3 parts perlite be suitable for growing?

  • HU-483617091
    2 days ago

    Al, would your Gritty mix be good for a Nepenthes, 'Alta' which is a tropical epiphytes?

    Dianne

  • tapla
    2 days ago

    I can't say - personally, I've never tried to grow a carnivorous plant. Is there a reason you don't want to use the conventional mix of dried sphagnum moss (not peat moss)

    with all-purpose or super coarse perlite?

    Al

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