Tapla's 5-1-1 Container Mix in More Detail (2024)

I recently joined the forum and discovered Al's 5-1-1 Mix, but I had several questions that Al was kind enough to answer by email. I also found the answers to other questions in several different threads. I thought it would be useful to organize all of the info in one place so that we could have easy access to it. 98% of the following has been cut/pasted from Al's postings, and I apologize in advance if I have somehow misquoted him or taken his ideas out of proper context. The only significant addition from another source is the Cornell method of determining porosity, which I thought would be germane. I have used a question and answer format, using many questions from other members, and I apologize for not giving them proper credit. Thanks to all who contributed to this information. Now, here's Al:

Tapla's 5-1-1 Mix

Many friends & forum folk grow in this 5-1-1 mix with very good results. I use it for all my garden display containers. It is intended for annual and vegetable crops in containers. This soil is formulated with a focus on plentiful aeration, which we know has an inverse relationship w/water retention. It takes advantage of particles, the size of which are at or just under the size that would guarantee the soil retains no perched water. (If you have not already read Al's treatise on Water in Container Soils, this would be a good time to do so.) In simple terms: Plants that expire because of drainage problems either die of thirst because the roots have rotted and can no longer take up water, or they starve/"suffocate" because there is insufficient air at the root zone to ensure normal water/nutrient uptake and root function.

I grow in highly-aerated soils with the bulk of the particles in the 1/16"-1/8" size, heavily favoring the larger particles, because we know that perched water levels decrease as particle size increases, until finally, as particle size reaches just under 1/8" the perched water table disappears entirely.

Ideal container soils will have a minimum of 60-75% total porosity. This means that when dry, in round numbers, nearly 70% of the total volume of soil is air. The term 'container capacity' is a hort term that describes the saturation level of soils after the soil is saturated and at the point where it has just stopped draining - a fully wetted soil. When soils are at container capacity, they should still have in excess of 30% air porosity. Roughly, a great soil will have about equal parts of solid particles, water, and air when the soil is fully saturated.

This is Cornell's method of determining the various types of porosity:

To ensure sufficient media porosity, it is essential to determine total porosity, aeration porosity, and water-holding porosity. Porosity can be determined through the following procedure:

* With drainage holes sealed in an empty container, fill the container and record the volume of water required to reach the top of the container. This is the container volume.

* Empty and dry the plugged container and fill it with the growing media to the top of the container.

* Irrigate the container medium slowly until it is saturated with water. Several hours may be required to reach the saturation point, which can be recognized by glistening of the medium's surface.

* Record the total volume of water necessary to reach the saturation point as the total pore volume.

* Unplug the drainage holes and allow the water to freely drain from the container media into a pan for several hours.

* Measure the volume of water in the pan after all free water has completed draining. Record this as the aeration pore volume.

* Calculate total porosity, aeration porosity, and water-holding porosity using the following equations (Landis, 1990):

The keys to why I like my 3-1-1 mix:

Q. Why do you use pine bark fines? Bark fines of fir, hemlock or pine, are excellent as the primary component of your soils. The lignin contained in bark keeps it rigid and the rigidity provides air-holding pockets in the root zone far longer than peat or compost mixes that too quickly break down to a soup-like consistency. Conifer bark also contains suberin, a lipid sometimes referred to as natures 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.

Q. What is the correct size of the fines? In simple terms: Plants that expire because of drainage problems either die of thirst because the roots have rotted and can no longer take up water, or they starve/"suffocate" because there is insufficient air at the root zone to insure normal water/nutrient uptake and root function.Pine bark fines are partially composted pine bark. Fines are what are used in mixes because of the small particle size. There will be a naturally occurring "perched water table" (PWT) in containers when soil particulate size is under about .125 (1/8) inch, so best would be particulates in the 1/16 - 3/16 size range with the 1/16-1/8 size range favored.

Note that there is no sand or compost in the soils I use. Sand, as most of you think of it, can improve drainage in some cases, but it reduces aeration by filling valuable macro-pores in soils. Unless sand particle size is fairly uniform and/or larger than about ½ BB size I leave it out of soils. Compost is too unstable for me to consider using in soils. The small amount of micro-nutrients it supplies can easily be delivered by one or more of a number of chemical or organic sources.

Q. Do you use partially composted pine bark fines? Yes - preferred over fresh fines, which are lighter in color.

Q. I found some Scotchman's Choice Organic Compost, which is made of pine bark fines averaging about 1/8" in size, and, after adding all ingredients, the 5-1-1 Mix had a total porosity of 67% and an aeration porosity of 37%. Is that all right? Yes, that is fine.

Q. What kind of lime do you use? Dolomitic.

Q. What amount of lime should I add if I used 10 gal of pine bark fines and the corresponding amount of the other ingredients? @ 5:1:1, you'll end up with about 12 gallons of soil (the whole is not equal to the sum of the parts when you're talking about soils), so I would use about 10-12 Tbsp or 2/3-3/4 cup of lime.

Q. What grade of coarseness for the lime? Most is sold as garden lime, which is usually prilled powder. Prilling makes it easier to use in drop & broadcast spreaders. The prills dissolve quickly. The finer the powder the quicker the reactive phase is finished. Much of the Ca and Mg will be unavailable until the media pH equalizes so the plant can assimilate the residual elements. Large pieces of lime really extend the duration of the reactive phase.

Q. Does this mean that I need to make up the soil in advance? Yes. 2 weeks or so should be enough time to allow for the reaction phase to be complete & residual Ca/Mg to become more readily available from the outset .

Q. During those 2 weeks, do I need to keep turning it and moistening it? No

Q. Can I go ahead and fill my 3-gal. containers, stack them 3-high, and cover the top one to prevent moisture loss during the waiting period? Something like that would be preferred.

Q. The perlite I use has a large amount of powder even though it is called coarse. Do I need to sift it to get rid of the powder? Not unless it REALLY has a lot - then, the reason wouldn't be because of issues with particle size - it would be because you had to use larger volumes to achieve adequate drainage & larger volumes bring with it the possibility of Fl toxicity for some plants that are fluoride intolerant.

Q. What about earthworm castings (EWC)? I think 10% is a good rule of thumb for the total volume of fine particles. I try to limit peat use to about 10-15% of soil volume & just stay away from those things that rob aeration & promote water retention beyond a minimal perched water table. If you start adding 10% play sand, 10% worm castings, 10% compost, 10% peat, 10% topsoil, 10% vermiculite to a soil, before long you'll be growing in something close to a pudding-like consistency.

Q. Do you drench the mix with fertilized water before putting in containers? No - especially if you incorporate a CRF. It will have lots of fertilizer on it's surface & the soil could already be high in solubles. If you added CRF, wait until you've watered and flushed the soil a couple of times. If you didn't use CRF, you can fertilize with a weak solution the first time you water after the initial planting irrigation.

Q. Do I need to moisten the peat moss before mixing with the pine bark fines? It helps, yes.

Selections from Notes on Choosing a Fertilizer

All that is in the "Fertilizer Thread" I posted a while back.

Q. Do you use the Dyna-Gro Foliage Pro 9-3-6 exclusively throughout the life of the plant, or change to something else for the flowering/fruiting stage? I use lots of different fertilizers, but if I had to choose only one, it would likely be the FP 9-3-6. It really simplifies things. There are very few plants that won't respond very favorably to this fertilizer. I use fast soils that drain freely & I fertilize at EVERY watering, and it works extremely well.

If you are using a soil that allows you to water freely at every watering, you cannot go wrong by watering weakly weekly, and you can water at 1/8 the recommended dose at every watering if you wish with chemical fertilizers.

Q. What about the "Bloom Booster" fertilizers? To induce more prolific flowering, a reduced N supply will have more and better effect than the high P bloom formulas. When N is reduced, it slows vegetative growth without reducing photosynthesis. Since vegetative growth is limited by a lack of N, and the photosynthetic machinery continues to turn out food, it leaves an expendable surplus for the plant to spend on flowers and fruit. There are no plants I know of that use anywhere near the amount of P as they do N (1/6 is the norm). It makes no sense to me to have more P available than N unless you are targeting a VERY specific growth pattern; and then the P would still be applied in a reasonable ratio to K.

Somewhere along the way, we curiously began to look at fertilizers as miraculous assemblages of growth drugs, and started interpreting the restorative effect (to normal growth) fertilizers have as stimulation beyond what a normal growth rate would be if all nutrients were adequately present in soils. ItÂs no small wonder that we come away with the idea that there are Âmiracle concoctions out there and often end up placing more hope than is reasonable in them.

What I'm pointing out is that fertilizers really should not be looked at as something that will make your plant grow abnormally well - beyond its genetic potential . . . Fertilizers do not/can not stimulate super growth, nor are they designed to. All they can do is correct nutritional deficiencies so plants can grow normally.

Q. Should I use organic ferts or chemical ferts in containers? Organic fertilizers do work to varying degrees in containers, but I would have to say that delivery of the nutrients can be very erratic and unreliable. The reason is that nutrient delivery depends on the organic molecules being broken down in the gut of micro-organisms, and micro-organism populations are boom/bust, varying widely in container culture.

Some of the things affecting the populations are container soil pH, moisture levels, nutrient levels, soil composition, compaction/aeration levels ..... Of particular importance is soil temperatures. When container temperatures rise too high, microbial populations diminish. Temps much under 55* will slow soil biotic activity substantially, reducing or halting delivery of nutrients.

I do include various formulations of fish emulsion in my nutrient program at certain times of the year, but I never rely on them, choosing chemical fertilizers instead. Chemical fertilizers are always immediately available for plant uptake & the results of your applications are much easier to quantify.

Q. Should I feed the plants every time I water? In a word, yes. I want to keep this simple, so IÂll just say that the best water absorption occurs when the level of solutes in soil water is lowest, and in the presence of good amounts of oxygen. Our job, because you will not find a sufficient supply of nutrients in a container soil, is to provide a solution of dissolved nutrients that affords the plant a supply in the adequate to luxury range, yet still makes it easy for the plant to take up enough water to be well-hydrated and free of drought stress. All we need to do is supply nutrients in approximately the same ratio as plants use them, and in adequate amounts to keep them in the adequate to luxury range at all times. Remember that we can maximize water uptake by keeping the concentrations of solutes low, so a continual supply of a weak solution is best. Nutrients donÂt just suddenly appear in large quantities in nature, so the low and continual dose method most closely mimics the nutritional supply Mother Nature offers. If you decide to adopt a "fertilize every time you water" approach, most liquid fertilizers can be applied at ¾ to 1 tsp per gallon for best results.

The system is rather self regulating if fertilizer is applied in low concentrations each time you water, even with houseplants in winter. As the plantÂs growth slows, so does its need for both water and nutrients. Larger plants and plants that are growing robustly will need more water and nutrients, so linking nutrient supply to the water supply is a win/win situation all around.

You can tell you've watered too much (or too little - the response is the same - a drought response) when leaves start to turn yellow or you begin to see nutritional deficiencies created by poor root metabolism (usually N and Ca are first evident). You can prevent overwatering by A) testing the soil deep in the container with a wood dowel ... wet & cool - do not water, dry - water. B) feeling the wick & only watering when it's dry C) feel the soil at the drain hole & only water when it feels dry there.

Soils feel dry to our touch when they still have 40-45% moisture content. Plants, however, can still extract water from soils until they dry down to about 25-30%, so there is still around a 15% cush in that plants can still absorb considerable moisture after soils first feel dry to us.

Q. When you water/fertilize, do you give it enough that 10% leaches out the bottom each time? Yes, I try to do that at every watering. Remember that as salts accumulate, both water and nutrient uptake is made more difficult and finally impaired or made impossible in severe cases. Your soils should always allow you to water so that at least 10-15% of the total volume of water applied passes through the soil and out the drain hole to be discarded. This flushes the soil and carries accumulating solutes out the drain hole. In addition, each thorough watering forces stale gases from the soil. CO2 accumulation in heavy soils is very detrimental to root health, but you usually can't apply water in volume enough to force these gases from the soil. Open soils allow free gas exchange at all times.

Q. Should I elevate my pots? The container will not drain the same % of water if it's sitting in a puddle, but the % won't be particularly significant. What will be significant is: if water (in a puddle) is able to make contact with the soil in the container through surface tension and/or capillarity, it will "feed" and prolong the saturated conditions of any PWT that might be in the container. However, if water can soak in or if it will flow away from the containers, there's no advantage to elevating when you're not using a wick.

Q. I like a pH of about 5.7. Is that about right? That's a good number, but you won't have any way of maintaining it in your soil w/o some sophisticated equipment. I never concern myself with media pH. That doesn't mean you should ignore water pH, though. It (water pH) affects the solubility of fertilizers; and generally speaking, the higher the water pH, the lower the degree of nutrient solubility.

Q. How do you repot? Some plants do not take to root-pruning well (palms, eg), but the vast majority of them REALLY appreciate the rejuvenational properties of major root work. I'm not at all delicate in my treatment of rootage when it comes time to repot (completely different from potting-up). Usually I chop or saw the bottom 1/2-2/3 of the root mass off, bare-root the plant, stick it back in the same pot with ALL fresh soil, use a chopstick to move soil into all the spaces/pockets between roots, water/fertilize well & put in the shade for a week to recover. I should mention that this procedure is most effective on plants with woody roots, which most quickly grow to be inefficient as they lignify, thicken, and fill the pot. Those plants with extremely fibrous root systems are easier to care for. For those, I usually saw off the bottom 1/2 - 2/3 of the roots, work a chopstick through the remaining mat of roots, removing a fair amount of soil, prune around the perimeter & repot in fresh, well-aerated soil.

I find that time after time, plants treated in this fashion sulk for a week or two and then put on a huge growth spurt (when repotted in spring or summer). Growth INVARIABLY surpasses what it would have been if the plant was allowed to languish in it's old, root-bound haunts. Potting up is a temporary way to rejuvenate a plant, but if you look ate a long-term graph of plants continually potted-up, you will see continual decline with little spurts of improved vitality at potting-up time. This stress/strain on plants that are potted-up only, eventually takes its toll & plants succumb. There is no reason most houseplants shouldn't live for years and years, yet we often content ourselves with the 'revolving door replacement' of our plants when just a little attention to detail would allow us to call the same plant our friend - often for the rest of our lives if we prefer.

Q. Is there any rule of thumb as to how often to root prune? I'm going to answer as if you included 'repotting' in your question. There is no hard, fast rule here. Some of you grow plants strictly for the blooms, and some plants produce more abundant blooms in containers when they are stressed in some manner. Often, that stress is in the form of keeping them root-bound. I'll talk about maintaining a plant's vitality & let you work out how you want to handle the degree of stress you wish to subject them to, in order to achieve your goals. Before I go on, I'd like to say that I use stress techniques too, to achieve a compact, full plant, and to slow growth of a particularly attractive plant - to KEEP it attractive. ;o) The stress of growing a plant tight can be useful to a degree, but at some point, there will be diminishing returns.

When you need to repot to correct declining vitality:

1) When the soil has collapsed/compacted, or was too water-retentive from the time you last potted-up or repotted. You can identify this condition by soil that remains wet for more than a few days, or by soil that won't take water well. If you water a plant and the soil just sits on top of the soil w/o soaking in, the soil has collapsed/compacted. There is one proviso though: you must be sure that the soil is wet before you assess this condition. Soils often become hydrophobic (water repellent) and difficult to rewet, especially when using liquid organic fertilizers like fish/seaweed emulsions. Make sure this effect is not what you're witnessing by saturating the soil thoroughly & then assessing how fast the water moves downward through the soil. The soils I grow in are extremely fast and water disappears into the mix as soon as it's applied. If it takes more than 30 seconds for a large volume of water to disappear from the surface of the soil, you are almost certainly compromising potential vitality.

I'll talk about the potential vitality for just a sec. Plants will grow best in a damp soil with NO perched water. That is NO saturated layer of water at the bottom of the pot. Roots begin to die a very short time after being subjected to anaerobic conditions. They regenerate again as soon as air returns to the soil. This cyclic death/regeneration of roots steals valuable energy from the plant that might well have been employed to increase o/a biomass, and/or produce flowers and fruit. This is the loss of potential vitality I refer to.

2) When the plant is growing under tight conditions and has stopped extending, it is under strain, which will eventually lead to its death. "Plants must grow to live. Any plant that is not growing is dying." Dr. Alex Shigo Unless there are nutritional issues, plants that have stopped extending and show no growth when they should be coming into a period of robust growth usually need repotting. You can usually confirm your suspicions/diagnosis by looking for rootage "crawling" over the soil surface and/or growing out of the drain hole, or by lifting the plant from its pot & examining the root mass for encircling roots - especially fat roots at the container's edge. You'll be much less apt to find these types of roots encircling inner container perimeter in well-aerated soils because the roots find the entire soil mass hospitable. Roots are opportunistic and will be found in great abundance at the outside edge of the soil mass in plantings with poor drainage & soggy soil conditions - they're there looking for air.

3) When the soil is so compacted & water retentive that you must water in sips and cannot fully flush the soil at each watering for fear of creating conditions that will cause root rot. This isn't to say you MUST flush the soil at every watering, but the soil should drain well enough to ALLOW you to water this way whenever you prefer. This type of soil offers you the most protection against over-watering and you would really have to work hard at over-fertilizing in this type of soil. It will allow you to fertilize with a weak solution at every watering - even in winter if you prefer.

Incidentally, I reject the frequent anecdotal evidence that keeping N in soils at adequacy levels throughout the winter "forces" growth or "forces weak growth". Plants take what they need and leave the rest. While there could easily be the toxicity issues associated with too much fertilizer in soils due to a combination of inappropriate watering practices, inappropriate fertilizing practices, and an inappropriate soil, it's neither N toxicity NOR the presence of adequate N in soils that causes weak growth, it's low light levels.

Q. Is there any rule of thumb as to how often to remove and replace the old soil? Yes - every time you repot.

As always, I hope that those who read what I say about soils will ultimately take with them the idea that the soil is the foundation of every container planting & has effects that reach far beyond the obvious, but there is a snatch of lyrics from an old 70's song that might be appropriate: "... just take what you need and leave the rest ..." ;o)