Either way, but I think the 5-1-1 calls for the PBF to be "partially composted" if memory serves.

I often use "soil conditioner" which is mostly PBF and usually has "forest products" so I sometimes skip the peat, depending on the amount of fines in the SC.

@woody I have never found a pine bark that was not seriously contaminated by sapwood. I have had much better luck with fir bark made for bonsai use.

I had a concern about American Countryside soil conditioner that Walmart sells. Was worried about the "forest products." So I called Sims Bark Co, who makes it, and they said that it's 99%+ pine bark. It's partially composted, and I can't see any sap wood, but it might just be hard to see since everything is dark. I also add very little peat, and so far haven't had any problems. last week, I did stumble on the mother load at a nursery near here. They sell "pine fines" by the yard. It's pure uncomposted pine fines for $30/yd.

@edweather Someone please correct me, but I think sapwood is usually white.

Is your pine fines a humous? If it requires filtering, don't forget that you will waste 50% of the material as filtered fines. If it requires filtering and you don't filter, then your soil isn't going to have the desired water retention property. There will be too much pooled water between the fines.

Yes, sapwood is white. As far as the rest of your post, I have no clue what you are talking about. Countryside Soil Conditioner is just about perfect right out of the bag.....partially composted pine fines. Just add perlite, and a little peat, and you're good to go. Have been doing this for years. No need to sift this, as there are no large pieces. Particle size for the 511 is dust to 3/8", and some up to 1/2".

@edweather Al (user Tapla) is the creator of the 511 mix and he explains why you do not want "dust" in your 511 mix here:

[https://www.houzz.com/discussions/container-soils-and-water-in-containers-long-post-dsvw-vd~1384093[(https://www.houzz.com/discussions/container-soils-and-water-in-containers-long-post-dsvw-vd~1384093)

The important part of this long post:

"A given volume of large soil particles have less overall surface area in comparison to the same volume of small particles and therefore less overall adhesive attraction to water. So, in soils with large particles, GFP more readily overcomes capillary attraction. They drain better. We all know this, but the reason, often unclear, is that the PWT is lower in coarse soils than in fine soils. The key to good drainage is size and uniformity of soil particles. LARGE PARTICLES MIXED WITH SMALL PARTICLES WILL NOT IMPROVE DRAINAGE because the smaller particles fit between the large, increasing surface area which increases the capillary attraction and thus the water holding potential. Water and air cannot occupy the same space at the same time. Contrary to what some hold to be true, sand does not improve drainage. Pumice (aka lava rock), or one of the hi-fired clay products like Turface are good additives which help promote drainage and porosity because of their irregular shape."

And specific to the use of bark fines:

"UNIFORM SIZE particles of fir, hemlock or pine bark are excellent as the primary component of your soils."

@edweather One of the things I have noticed is that there are container gardeners here who use awful soil (because for example, they don't filter out fines) yet they still get brilliant results. Why is that? Most of the time these are people who either grow in arid environments or grow indoors, and they have massive experience with plants and as a result, they know to not overwater the plant.

If you can prevent the plant from receiving too much water, I am pretty convinced you can grow it in almost anything, as long as you make sure it receives enough organic material for its type, and you don't get the pH dramatically wrong. This is particularly true for plant types like succulents and cactus, which do not appreciate too much water in any kind of soil.

One of the reasons I like the gritty mix with carefully sized particles is that it tolerates my mistakes as an amateur when I do overwater the plant. It allows me to keep many types of succulents outdoors, where they might receive weeks of rain during a winter. It's not going to make plants impervious to overwatering, but it does extend the margin of error measurably.

Why do you add peat then? TO GET WATER RETENTION!!!. I can quote ad nauseaum where some pine dust is fine, per Al and many others. The more dust, the less peat you need to add for the desired water retention. The minimal amount of dust/composted pine fines isn't going to increase the perched water level. I'm done with this thread. Have you ever messed with dry peat moss on a breezy day. Without a DUST mask, it's not fun. Direct quote from:

Container Soils - Water Movement & Retention XIV

".....5 parts pine bark fines (partially composted fines are best):

That is exactly what I use. Maybe someone else will pick up this conversation, I don't know what else to say.

Peat is a single large reservoir of water. They are larger particles with a smaller surface area. That said, many people would argue that peat is a lousy soil ingredient and ends up creating a tangled mess that begs to be repotted every few years. I would only use peat for plants like carnivorous that want an extremely water drenched soil. Your mileage may vary.

Regardless of what results you have achieved, the fact that small particles have a larger surface area than an equivalent mass of large particles - and therefore attract more pooled water between the particles - is just laws of physics. There is no disputing the physics of surface area based on particle size and how that affects water between those particles.

As I said, there are a dozen ways to skin a cat, and given a high skill level with plants I am pretty convinced that any good gardener can make any soil work well. But in soils where these things are observed strictly - such as gritty mix - mixing the soil with dust fines completely undoes the value of the soil. You end up with lots of pooled water throughout the soil material.

I believe you are confusing the gritty mix with the 511 mix when you talk about exclusion of the "dust", or smallest particles, in the mix.

The gritty mix is designed specifically to exclude a perched water table, and this is done through a uniform particle size. Including smaller particles ("dust") would, indeed, defeat that purpose.

The 511 mix is not designed to completely avoid a perched water table. It will have one, but it will be less than in commercially available mixes. The inclusion of a small percentage of "fine" material in this mix composed otherwise of "coarse" material will not destroy the aeration of the mix, because the amount of fine material will not be enough to "fill in all the gaps".

"Small percentage", however, is key, but the 511 mix is less precisely defined than the gritty mix in its proportions by particle size. Pine bark fines are usually a gradation of sizes, and not uniform. And the peat can be completely excluded if your pine bark already has "enough" fine material. How much is "enough"?

Beats me. I have found through trial and error that the pine bark fines I have available to me sometimes have enough fine material that even without adding peat, the mix stays wet for longer than I want. Screening all the fine material out (using a 1/16" insect screen) produces a mix with too little water retention. So I screen my bark, then add 1 part fines (screened through the 1/16" mesh) back in to 5 parts bark (bigger than 1/16"), and skip the peat. This creates better uniformity in my 511 mix, and helps mitigate the lack of uniformity in my bark supply.

You linked to the oldest of 22 threads that Al started to discuss his mixes. Have you read the rest of them? They do a good job explaining why the particle sizes are different in the gritty mix and the 511 mix - and a fair amount of the detailed discussion and explanation happens in the comments section as he answers questions that people ask.

@illstep gritty mix does not exclude a perched water table. It just minimizes it.

Using fines in a soil doesn't just make the perched water table grow higher. It puts pooled water into every part of the soil, as a consequence of the physics of the additional surface area in the soil that uses dust size particles.

I have never been a fan of the 511 mix, and one of the many reasons for that is the internal inconsistency within Al's own posts. Some of Al's posts clearly state that adding sand and small particles to a soil do not make it drain better and he explains - correctly - the physics of why small particles in the soil will leave pooled water throughout the soil and create bad drainage.

Other posts from Al seem to hedge on that and alternate between denying the physics and implying that it is okay for things to be wetter for some plants. To me, it is a clear choice between crystal-clear science and fuzzy logic. 511 involves a lot of imprecise statements, fuzzy logic about water retention that is not science-based, and unquantified assertions about which plants tolerate which amounts of water retention in which conditions.

Really what 511 seems to want to do was to adapt the gritty mix to have more organic matter in the soil to feed plant roots without requiring constant doses of fertilizer. I guess it did accomplish that but at the cost of very fuzzy logic around water retention issues.

Since the other poster has great success with 511, and I don't find any reason to use it, I doubt that this conversation is going to be productive.

The 511 mix was never designed to be a "perfect" mix. It was designed to be a "better" (than store bought), "cheap", and "short term" mix, and Al has been up front about all three of those things.

It still appears to me that you are expecting the same thing from the 511 mix as from the gritty mix, and I'm not sure why. The gritty mix is superior for structure, aeration, durability, etc. The 511 mix still has uses, despite its flaws. Seems simple to me. :)

Not sure why you think the 511 mix doesn't need consistent fertilizer application. The breakdown of its organic components seems unlikely to be fast enough to feed much of anything, and I haven't seen a single mention by Al or others about it not needing constant fertilization.

Westes: Both illsstep and gardengal gave you great advise on the difference between 511 and gritty mix. Reading your posts here and in other threads I think you are a bit confused about PWT, how water moves through a medium and the physics behind it. I will try to address some of it without going into finer nuances.

First, PWT is, by definition, the height of the zone at the bottom of pot where it is 100% saturated with water. PWT happens because of capillary action of water and it is determined by the size of the air gap between particles. And when particles themselves are porous like bark, peat, turface etc, then the size of the pores in those particles also contribute to the capillary action. The smaller the size of the pore, greater is the capillary force pulling the water up through the medium. Gravity pulls water down and capillary force pulls it up. At some height of water (the PWT) the two forces cancel each other and water cannot move up anymore. The rest of the mix above the PWT will have some air depending on the size of the pores. The air in these spaces will have near 100% humidity. This is the ideal zone for the plant roots to thrive.

Contrary to your belief, using more fine particles in soil will increase the PWT since it reduces the pore size and thus increases the upward capillary force. Peat and bark actually resist becoming wet but once they are wet water can stick to the surface. In case of peat the air gap between particles of peat is so small that capillary action will pull the water up against gravity making more particles wet. PWT will be higher when more peat is used but above the PWT water will not pool as you think. The mix above PWT will not be 100% saturated.

A properly mixed gritty mix will have effectively zero PWT. Often a lot of us will use the finer particles of turface (1/16 - 1/8) to avoid wasting it and save some money. As long as it is a small fraction of the mix it does not increase the PWT for gritty mix significantly. The only component in gritty mix that will break down with time is bark. As it breaks down the mix becomes more water retentive and PWT increases.

511 mix is a cheaper, lighter and less durable compromise as has been noted above. Granted, it is not as exact as the gritty mix but it is an excellent compromise for many plants as long as you understand the properties of the soil. And water and fertilize accordingly.

Even gritty mix is not entirely perfect. There are many other bonsai mixes that are similar that use lava rock, pumice, akadama, etc. Some even grow in pure pumice and will hardly degrade over time. I have several plants in pure pumice and/or lava rock. If you want absolute scientific control over the plant growing medium nothing comes close to hydroponics. But if you want your plant to be in the garden for display and enjoyment and be portable, gritty or other bonsai mixes are as close to hydroponics as can be achieved.

The difference in 5-1-1 and gritty mix is mostly based on longevity of the mix between necessary re-pot/root pruning.

Gritty mix holds more water than you think.

It is not just for succulents. I have several pines and JMs in GM for up to 6 years (which were repotted this year) and they were outside in dappled shade through 95 degree temps last summer. The only time I watered was if it did not rain for more than a 7-10 days.

Al's logic is LITERALLY based on thousands of years of Bonsai practitioners who have kept potted trees that are 400-600 years old, or more!

Rest assured, on 5-1-1 and Gritty Mix... Al's logic and physics are unassailable.

@tropicofcancer you are making my points for me. You didn't read what I wrote clearly.

You said "Contrary to your belief, using more fine particles in soil will increase the PWT since it reduces the pore size and thus increases the upward capillary force." In fact that is not contrary to my belief. As I said earlier in this thread "...gritty mix does not exclude a perched water table. It just minimizes it." That by itself makes clear that I understand that soils with smaller particles have a higher PWT.

A properly mixed gritty mix will not have an effectively zero PWT. That would be equivalent to saying that a properly mixed gritty mix has no capillary action at all, which is not true. I have done experiments with the very largest turface, bark, and stone particles, and I never fail to get a PWT that stays around for a long time and can be easily measured with a skewer. I don't see how making this point helps this discussion, particularly since we both agree that soils with small particles have higher PWT than soils that are coarse.

PWT isn't the important concept in what I was writing. The point I was making was that a soil with lots of fine particles has such strong capillary forces that it is easy for the soil to become water drenched and stay that way. If you want to see that point, take some turface and filter it to coarse and fine particles. Make a 100% turface soil from each. The coarse turface particles have a small PWT and create a very nice high-humidity environment a few inches down from the surface. The soil made of turface fines is a water-logged swamp.

The point that others seem to be making is that some plants like that additional level of water retention. I'm okay with that idea.

Westes: I read your writeup again and I did miss the fact about fine particles raising the PWT. My apologies.

I am not trying to show you down but here are my added points:

Regarding fine particles you said "It puts pooled water into every part of the soil, as a consequence of the physics of the additional surface area in the soil that uses dust
size particles." It does not cause water pool everywhere. Only up to the PWT. Additional surface area is not as important as the many tiny gaps created between particles to draw the water up via capillary action. Additional surface area affects the volume of the water held, not the height of the PWT.

You said: "That would be equivalent to saying that a properly mixed gritty mix has no capillary action at all, which is not true". But it is fairly true. There are two capillary actions: one between the particles and the other within a porous particle like bark, turface and other components. In case of gritty mix, the space between the particles are too large to support significant capillary action. The pores within the particles are very small and will draw up water to a considerable height - as long the porous particle touch each other in some ways. That does not mean there is any significant water is in between the particles - a requirement for PWT. This is what bonsai practitioners actually aim for - zero PWT and yet all particles are saturated with water.

You said: "I never fail to get a PWT that stays around for a long time and can be easily measured with a skewer". I cannot figure out how you can measure PWT with a skewer. If you insert a skewer and the bottom 4 inches come out damp all that means is that there is enough water in the bottom 4 inches to make the skewer damp. It does not mean that the bottom 4 inches is saturated or is the PWT.

A better, not perfect, way to figure out if there is any PWT is too tilt the pot at 45 degree angle towards a hole in the pot at its edge and see if any water flows out. Do this after say 20 minutes after a heavy watering so that excess water has a chance to flow out. Follow that with rapid up and down movement of the pot. This will cause the capillary force to be momentarily disrupted and cause water in the gaps between particles to be released and will flow out. In a properly mixed gritty mix almost next to nothing will flow out using any of the above methods.

You said: "The point that others seem to be making is that some plants like that
additional level of water retention. I'm okay with that idea." Most plants do not like any extra level of water retention. There may be a very few house plants that fall into that category. It is we who do not like to water too frequently. So all the mixes are a sort of a compromise between what the plant wants and how much attention we can afford for the plants.

@tropicofcancer I just wanted to make sure that we were talking about the correct problems, so I think we are back on track.

I think when you talk about finer particles creating more space between particles, that is just a side effect of more surface area. Larger particles with less total surface area leave less space between those larger particles. This is just looking at the same issue from two different perspectives.

If I take Turface fines and water them, I get a water-saturated mess that is very slow to dry. Are you saying that this means the perched water table actually goes the entire length of the container to the top of the soil? Let me try to grasp the physics of just that trivial case before we start to talk about 511 again.

To the OP: Apologies for diverting the topic but please do pipe in if are still in doubt.

Westes: "I think when you talk about finer particles creating more space between
particles, that is just a side effect of more surface area. Larger
particles with less total surface area leave less space between those
larger particles. This is just looking at the same issue from two
different perspectives."

It is the other way around. Capillary force depends on the space between surfaces. Consider a wick made of fine strands of fibers. If you loosely pack it then the spaces between strands are large and it will not wick as well. But if you tightly wind the same strands the spaces between strands decreases and it will wick up water much better. The surface area has not changed but the capillary force increases considerably. This is the principle that a mop uses to draw up the water from the floor.

Another way to look at PWT is to think of a jigsaw puzzle vertically.
The pieces themselves are big compared to the spaces in between them. Let us assume the pieces cannot absorb water. Let us say they are made of plastic and when they are put together there is still a tiny strand of space between them and is the same throughout. If
the space is small enough water will wick up from the bottom through
those spaces to quite a height. But the height achieved by wicking water
is determined by the space between the pieces and not the size of the
pieces themselves. And for this theoretical jigsaw puzzle, the height the water will reach be fairly fixed - no more no less.

"If I take Turface fines and water them, I get a water-saturated mess
that is very slow to dry. Are you saying that this means the perched
water table actually goes the entire length of the container to the top
of the soil? Let me try to grasp the physics of just that trivial case
before we start to talk about 511 again."

If you take your turface medium it will have a fixed PWT. Let us say that is 5 inches or 10 inches or whatever the medium supports. Below that height it will be 100% saturated. Above that height it will not be 100% saturated. And as you go higher it will be less so. When I say saturated, it means both the particles and the air spaces are filled with water. Above PWT the particles may be saturated but not the spaces in between. In fact, the spaces in between will be a mixture of air and water vapor making it very humid. The relative humidity in the spaces may be 100% but it is very different from saying that space is 100% water.

Slow to dry does not mean there is a PWT. All it means is that turface is saturated with water. Does not mean that the spaces between them is. And turface is pretty reluctant to give up its water. The surface bond strength between water and the clay in turface is pretty strong. It takes a lot of energy to break that bond and it becomes increasingly (exponentially) harder as the turface becomes drier. Cactus like plants have an immense ability to exert phenomenal force to extract water. They have evolved to do that. Water loving plants lack that ability and need more freely available water not tightly bound to the medium. Without any roots to suck that water any medium will feel damp/wet for a long time. Temperature plays a role here too. Lower the temperature harder it is for the roots to extract water from a medium.

@tropicofcancer, okay now we understand each other on spaces between particles. Large particles have more space between them. The reason that smaller particles have more free water between particles is because of stronger capillary forces. I am guessing that is because the increased surface area of more small particles increases the area in which water's adhesion force is applied.

When I filter out Turface fines and water it, there is free standing water between the particles that remains for a long time, all the way to the top of the pot. You never clearly agree with your own point on this: Are you saying that this means the PWT comes all the way to the top of the pot? Again, this is not saturated Turface. This is free standing water between the Turface fines.

So the "art" of gardening here - once you understand all this science - is to find the right amount of small particles to allow into the soil, tailored to the needs of specific plants. 511 is an attempt to develop a good all-purpose soil for plants that like higher amounts of water retention. But I supposed a really skilled practitioner (certainly not me, yet) could fine-tune soils by mixing a soil with only large filtered particles, then adding back in very precise amounts of fine particles to support a given type of plant.

" I am guessing that is because the increased surface area of more small
particles increases the area in which water's adhesion force is
applied." - Yes, although I do not know or understand what happens when the particles are too small and what is too small. For practical purposes in case of soil mixes, we assume 1/16 inches is too small.

"When I filter out Turface fines and water it, there is free standing
water between the particles that remains for a long time, all the way to
the top of the pot" - What is the size range of the turface particles? As I said if most of it is too small it is likely that will have a very high PWT. If the pot is shorter than PWT then water will fill to the top.

"Again, this is not saturated Turface. This is free standing water between the Turface fines" - I do not understand this statement. How can you have turface not saturated and at the same time have water in between turface? Can you explain how you did this experiment?

"So the "art" of gardening here - once you understand all this science -
is to find the right amount of small particles to allow into the soil" - Absolutely. Science provides the method to the madness or art whichever you like.

"511 is an attempt to develop a good all-purpose soil for plants that like higher amounts of water retention." - Correct. It is also a compromise to reduce the need to water as often.

When I filter out Turface the "fines" are all smaller than 1/16th of an inch.

I was not trying to say that the Turface fines are not saturated. I was trying to distinguish two cases:

1) Turface fines are saturated but there is not much free water between the particles

2) Turface fines are saturated but there is also a lot of free water between the particles

When I saturated Turface fines - all below 1/16th of an inch - I get a slush that has a lot of free water to the top of the soil. It is also extremely slow to dry.

Anything less than 1/16 inch is just too small and will cause this problem. If I think pine bark has a lot of it I screen it out. But my recent bags of pine bark from Agway had very little of it. For gritty anything below 1/16 gets rejected (turface) and for pine bark below 1/8 gets rejected. Sometimes turface bags may contain a large portion between 1/16 and 1/8. In that case, I screen it out first and then add back a portion of it.

@tropicofcancer I wasn't trying to define what goes in gritty mix. I was showing the difference in water retention for a 100% Turface soil using large particles versus small particles. The point of that was to get you to clearly state your point. You seemed to be saying that in the case of the small Turface particles the PWT extended all the way to the top of the pot. To me it seems like this is not all PWT, and the issue is free water adhesion to lots of surface area on small particles.

"You seemed to be saying that in the case of the small Turface particles the PWT extended all the way to the top of the pot" - And very likely beyond the pot. You see PWT is a property of the mix and not the size of the pot. In your case, the PWT is higher than the pot. Use a taller pot if you want to find the PWT of your fine turface mix. It should be tall enough so that you can see the boundary between the saturated and unsaturated part.

"To me it seems like this is not all PWT, and the issue is free water adhesion to lots of surface area on small particles." That is what causes the capillary action, when adhesive force between water and solid surface exceeds the cohesive force that keeps water molecules together. For example read this: https://water.usgs.gov/edu/capillaryaction.html