The perils of pinebark

Adair M

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I know, some of you love the stuff. And it’s a staple of many professionals. But hear me out. It’s really a problem...

it’s the shape of the particles. Pine bark is flat on two sides. Oh, when you first mix up your soil, their orientation is random. But, every time you water, you create a little flood of water from the surface down to the drain holes. And that water pushes on the bark. Moves it. Reorients it.

when that bark particle is pressed up against the screening covering the drain hole, it eventually finds a way to lay flat against it. The other pieces around it do, too. And the ones above. They orient themselves to resist the water, creating a flat layer, and stack themselves like bricks.

this creates an effective water barrier! Which makes the soil too wet, and can lead to root rot.

Last night, we had a gully was her of a storm. I use pine bark mini-nuggets in my landscape around my pond. Many got washed into my pond. They floated down to the skimmer, many were caught by the filter box, but some are smaller, and slip thru. My pond has a drain pipe behind the skimmer to drain off excess rainfall. The mini-nuggets fall down into the drain, and can plug it up. So, I fashioned a screen wire covering made out of hardware cloth, the same hardware cloth I used to use to make drain hole screens (before I switched to plastic). Well, the little pieces of bark would pile up against the screen. And so would the water! Oh, it still drained, slowly, but more and more pine bark would pile up, and the water level rose. Eventually, my pond flooded over. Held back by little pieces of bark.

if pine bark can cause a 6000 gallon pond to flood, I have no doubt it can stop up the drainage in a bonsai pot.
 

Wires_Guy_wires

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But if we shake and press down our soil basically stacking particles so that they can hardly move, how would those bark particles move, twist and flip?
I can imagine them moving on the bottom and on the top layer, but my watering wand has such an easy flow that it hardly moves perlite.

Maybe my bark is too large?

Anyhow, I don't use a whole lot of it. I don't really like it for other things than a ground cover.
 

Adair M

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But if we shake and press down our soil basically stacking particles so that they can hardly move, how would those bark particles move, twist and flip?
I can imagine them moving on the bottom and on the top layer, but my watering wand has such an easy flow that it hardly moves perlite.

Maybe my bark is too large?

Anyhow, I don't use a whole lot of it. I don't really like it for other things than a ground cover.

I think the term you need to think about is “settle”. Over time, the soil will settle. Compress.

compare the shape of pine bark particles to marbles. The round shape of marbles prevents compression. To fill the air space in a container full of marbles would require smaller particles to occupy that air space.

we want to keep the open air space as best we can. Roots will fill it, and when they do, we have to repot.

Using soil particles with a rounded shape preserves the air space which provides for good drainage better than particles that have flat shapes.

the flat shape is also the problem with using turface. It “stacks”, forming a water barrier.

sharp angular substrates will eventually “pack” solid, especially if they are composed of varied sizes. The small particles will wedge in between the larger particles. They use “crush and run” gravel to build gravel roads and driveways. It’s loose at first, but over time and use, it packs to become quite solid. A road made of similiar size pea gravel would stay loose and slippery! (Until enough of the rocks crack and break to begin to pack). That’s why they don’t build roads out of pea gravel!
 

MrWunderful

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I hear what you are saying, but for the record I have been using pine bark in my 1:1:1 to “wetten” the mix for deciduous trees in development for 5 years without a single pot being plugged up.

just my experience though.

My better deciduous trees get 100% akadama (which is IMO the best option for most deciduous) but expensive for trees that get huge amounts of coarse root growth and get repotted every year.
 

Wires_Guy_wires

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I think the term you need to think about is “settle”. Over time, the soil will settle. Compress.

compare the shape of pine bark particles to marbles. The round shape of marbles prevents compression. To fill the air space in a container full of marbles would require smaller particles to occupy that air space.

we want to keep the open air space as best we can. Roots will fill it, and when they do, we have to repot.

Using soil particles with a rounded shape preserves the air space which provides for good drainage better than particles that have flat shapes.

the flat shape is also the problem with using turface. It “stacks”, forming a water barrier.

sharp angular substrates will eventually “pack” solid, especially if they are composed of varied sizes. The small particles will wedge in between the larger particles. They use “crush and run” gravel to build gravel roads and driveways. It’s loose at first, but over time and use, it packs to become quite solid. A road made of similiar size pea gravel would stay loose and slippery! (Until enough of the rocks crack and break to begin to pack). That’s why they don’t build roads out of pea gravel!

The settling is what I do after a repot by jamming a wooden peg into the soil for hours and then watering it thoroughly.
The thing is, I would expect the settling of the soil, as well as gravity, to keep the bark in place. As you mentioned; bark is flat on both sides, it's also lighter than my soil particles. Soil is basically a irregular particle matrix, this would naturally hinder particles that don't fit through the open space from moving.

When doing column chromatography, this is exactly the physical property we use: we set up a colum with a certain known size matrix (sephadex for instance to filter proteins) and we capture the runoff at different time intervals to separate tiny particles that come first from larger ones that take more time to pass through the gaps. But if the particle is bigger than the 'open space' in the matrix, it doesn't move at all until we break up the matrix itself by stirring and shaking. A tedious process. I believe that soil works the same way.

I think that by watering alone, you wouldn't be able to get a piece cut-to-relative-size cardboard through a bowl of marbles. Not without shaking it. This experiment can easily be done at home.

Or.. You're using very tiny bark particles!

I understand the warning, I've had issues with bark in the past. In my case I just used too much of it.
 

Anthony

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These were done 7 days or so ago.
Renewed the compost.
mix is - 7 parts 5mm silica based gravel
3 parts aged compost

pine pot.jpg

J.B.pine from seed - some maybe 10 years old

pine pot 2.jpg
 

Adair M

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The settling is what I do after a repot by jamming a wooden peg into the soil for hours and then watering it thoroughly.
The thing is, I would expect the settling of the soil, as well as gravity, to keep the bark in place. As you mentioned; bark is flat on both sides, it's also lighter than my soil particles. Soil is basically a irregular particle matrix, this would naturally hinder particles that don't fit through the open space from moving.

When doing column chromatography, this is exactly the physical property we use: we set up a colum with a certain known size matrix (sephadex for instance to filter proteins) and we capture the runoff at different time intervals to separate tiny particles that come first from larger ones that take more time to pass through the gaps. But if the particle is bigger than the 'open space' in the matrix, it doesn't move at all until we break up the matrix itself by stirring and shaking. A tedious process. I believe that soil works the same way.

I think that by watering alone, you wouldn't be able to get a piece cut-to-relative-size cardboard through a bowl of marbles. Not without shaking it. This experiment can easily be done at home.

Or.. You're using very tiny bark particles!

I understand the warning, I've had issues with bark in the past. In my case I just used too much of it.

First off: it sounds like you are chopsticking too much! Doing a lot of chopsticking breaks roots. And if you put in a “drainage layer” if larger particle soil in the bottom if your pot, doing a lot of chopsticking will force small particles down into the drainage layer, effectively filling the open space the large particles would otherwise create, and two, it pulls the large particles up from the bottom, and into the “main soil”. Which means you have sieved your soil for nothing! It’s now all mixed up!

This settling doesn’t happen all at once. When we pot a bonsai tree, we generally expect it to be good for 2, 3, or 4 years before we have to repot again. That’s a lot of waterings. A lot of rainfalls. Roots grow thru. And dislodge the particles. The next heavy rain can then shift them. Nothing is static in the pot. Eventually, a mat of roots will grow and cover the bottom if the pot, slowing drainage. If you have a substrate that also tends to pack, and slow drainage, you create a double whammy!

The higher percentage the mix that is pine bark, the more likely the stacking effect. Using turface which is also flat on two sides compounds the problem.

someone asked about “composted pine bark”. I don’t know exactly what that is. I would say it depends on the shape of the particles. That said, if there are a lot of fines, well, those fines are going to fill the air space.
 

Mellow Mullet

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I have been using pine bark and fir bark for longer than I can remember and have never had a plugging issue. I think that once the soil is packed into the pot, the bark is kinda locked into place. I have repotted trees after three or four years and still have the bark distributed throughout the soil, not migrated to the bottom of the pot. I hate that your pond overflowed, it was very nice, but I think you are comparing apples to oranges, or maybe even tomatoes. The same thing that happened to you with the pine nuggets happens all the time to me with oak leaves in my rain gutters.
 

Adair M

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I have been using pine bark and fir bark for longer than I can remember and have never had a plugging issue. I think that once the soil is packed into the pot, the bark is kinda locked into place. I have repotted trees after three or four years and still have the bark distributed throughout the soil, not migrated to the bottom of the pot. I hate that your pond overflowed, it was very nice, but I think you are comparing apples to oranges, or maybe even tomatoes. The same thing that happened to you with the pine nuggets happens all the time to me with oak leaves in my rain gutters.
I used to use pine bark and turface as my soil mix. And while I don’t remember “plugging” the drain holes being a specific issue, I did struggle with root rot. Perhaps I was (and still am) a chronic overwaterer. But, since I have switched to all inorganic soils with rounded particles, no more root rot.

But, life is full of perils. You can cross the road without looking left and right without looking and get away with it. For a while. Maybe.

the pond is fine, by the way. The filters will have it cleaned up in a day or two. The fish are happy!
 

Lazylightningny

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I've been using pine bark reclaimed from the soil of nursery plants for quite a few years now. I assume it's composted, as it's been in the pot for a good many years. I have not noticed any plugging issue. However, what does happen is that the bark naturally flakes after time, and creates smaller, flatter flakes that are not conducive to good bonsai soil. For this reason, I now only use pine bark in larger developing material, and replace it with akadama in more developed material, or smaller plants. I don't claim to be anywhere near Adair's skill level; he's head and shoulders above me, but this seems to be working for me.
 

Lazylightningny

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Perhaps I was (and still am) a chronic overwaterer. But, since I have switched to all inorganic soils with rounded particles, no more root rot.
That's one of the great things about inorganic substrate. No such thing as overwatering anymore! (as long as all organic material has been removed from the roots) With organic substrate, it used to take years to learn how to water properly. Inorganic substrate has eliminated that problem.
 

Adair M

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That's one of the great things about inorganic substrate. No such thing as overwatering anymore! (as long as all organic material has been removed from the roots) With organic substrate, it used to take years to learn how to water properly. Inorganic substrate has eliminated that problem.
Couldn’t have said it better myself!
 

Wires_Guy_wires

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First off: it sounds like you are chopsticking too much! Doing a lot of chopsticking breaks roots. And if you put in a “drainage layer” if larger particle soil in the bottom if your pot, doing a lot of chopsticking will force small particles down into the drainage layer, effectively filling the open space the large particles would otherwise create, and two, it pulls the large particles up from the bottom, and into the “main soil”. Which means you have sieved your soil for nothing! It’s now all mixed up!

This settling doesn’t happen all at once. When we pot a bonsai tree, we generally expect it to be good for 2, 3, or 4 years before we have to repot again. That’s a lot of waterings. A lot of rainfalls. Roots grow thru. And dislodge the particles. The next heavy rain can then shift them. Nothing is static in the pot. Eventually, a mat of roots will grow and cover the bottom if the pot, slowing drainage. If you have a substrate that also tends to pack, and slow drainage, you create a double whammy!

The higher percentage the mix that is pine bark, the more likely the stacking effect. Using turface which is also flat on two sides compounds the problem.

someone asked about “composted pine bark”. I don’t know exactly what that is. I would say it depends on the shape of the particles. That said, if there are a lot of fines, well, those fines are going to fill the air space.

I'll have a look at how they perform over the next few years and keep your advice in mind ;-)

I see what you're trying to say Adair, but aren't the inorganic particles settling just as much, or even more than the bark due to their weight? I mean, if put a rock on a twig, the twig is locked in place. Do that with a bunch of tiny rocks, and it'll probably stay put as well. The heavy particles settle faster and lock the lighter ones in place until they fall apart.
If roots grow through bark, they keep the bark in place or break it up into finer particles. But if roots can grow there, so can fungi - unless you're using a lot of antibiotics. Those filaments are pretty strong too, they're being used to make furniture nowadays. I need a chisel to break up my Ganoderma lucidum cultures if they're grown on wood. As a matter of fact, when I removed the soil blend high in bark flakes from my collected juniper, there were actual nuggets of fungi keeping both the inorganic and organic particles together. After three weeks in the sun and rain, they still don't fall apart until I crunch them manually.

Loss of air space and over watering soils high in organics is my main concern. With purely inorganic, I don't have those issues at all either. But purely inorganic is terrible for seedling root development, taproots all over the place!

When re-purposing my old soil, it takes quite some shaking to get the bark pieces on top. I believe soil is a dynamic thing, it moves, but not that much.

I'll set up an experiment though. I have enough empty pots lying around. If the bark flakes haven't moved in fall, I don't expect them to move any later than that either.
 

Adair M

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I'll have a look at how they perform over the next few years and keep your advice in mind ;-)

I see what you're trying to say Adair, but aren't the inorganic particles settling just as much, or even more than the bark due to their weight? I mean, if put a rock on a twig, the twig is locked in place. Do that with a bunch of tiny rocks, and it'll probably stay put as well. The heavy particles settle faster and lock the lighter ones in place until they fall apart.
If roots grow through bark, they keep the bark in place or break it up into finer particles. But if roots can grow there, so can fungi - unless you're using a lot of antibiotics. Those filaments are pretty strong too, they're being used to make furniture nowadays. I need a chisel to break up my Ganoderma lucidum cultures if they're grown on wood. As a matter of fact, when I removed the soil blend high in bark flakes from my collected juniper, there were actual nuggets of fungi keeping both the inorganic and organic particles together. After three weeks in the sun and rain, they still don't fall apart until I crunch them manually.

Loss of air space and over watering soils high in organics is my main concern. With purely inorganic, I don't have those issues at all either. But purely inorganic is terrible for seedling root development, taproots all over the place!

When re-purposing my old soil, it takes quite some shaking to get the bark pieces on top. I believe soil is a dynamic thing, it moves, but not that much.

I'll set up an experiment though. I have enough empty pots lying around. If the bark flakes haven't moved in fall, I don't expect them to move any later than that either.

the issue I’m discussing here isn’t organic vs inorganic, it’s particle shape.
 

Mellow Mullet

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I used to use pine bark and turface as my soil mix. And while I don’t remember “plugging” the drain holes being a specific issue, I did struggle with root rot. Perhaps I was (and still am) a chronic overwaterer. But, since I have switched to all inorganic soils with rounded particles, no more root rot.

But, life is full of perils. You can cross the road without looking left and right without looking and get away with it. For a while. Maybe.

the pond is fine, by the way. The filters will have it cleaned up in a day or two. The fish are happy!

Root rot, how much did you use? I only use a small amount, it makes up around 10 -20 % of the total mix - depending on the tree, the rest is pumice and lava. I used to use turface when that was all I could get, but now only use it for really small stuff, like mame or for a top dressing.

I never cross without looking both ways.

Glad the fish are happy.
 

Anthony

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Composted pine bark, will re-adapt itself to a different
shape whan in use.
Non composted has to still decay and pine takes a while
to compost.
Hence the use as a decorative cover.
Hence the problems Sifu is mentioning.
Good Day
Anthony
 

Adair M

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Root rot, how much did you use? I only use a small amount, it makes up around 10 -20 % of the total mix - depending on the tree, the rest is pumice and lava. I used to use turface when that was all I could get, but now only use it for really small stuff, like mame or for a top dressing.

I never cross without looking both ways.

Glad the fish are happy.
Oh, back in the day, pine bark, in the form of “soil conditioner”, was maybe 50% of the mix with granite grit and turface each 25%.

This was back in the ‘80’s. Never heard about using lava or pumice back then. And I had never heard of akadama, either. We thought using Turface was “high tech”! Lol!!!
 

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I know, some of you love the stuff. And it’s a staple of many professionals. But hear me out. It’s really a problem...

it’s the shape of the particles. Pine bark is flat on two sides. Oh, when you first mix up your soil, their orientation is random. But, every time you water, you create a little flood of water from the surface down to the drain holes. And that water pushes on the bark. Moves it. Reorients it.

when that bark particle is pressed up against the screening covering the drain hole, it eventually finds a way to lay flat against it. The other pieces around it do, too. And the ones above. They orient themselves to resist the water, creating a flat layer, and stack themselves like bricks.

this creates an effective water barrier! Which makes the soil too wet, and can lead to root rot.

Last night, we had a gully was her of a storm. I use pine bark mini-nuggets in my landscape around my pond. Many got washed into my pond. They floated down to the skimmer, many were caught by the filter box, but some are smaller, and slip thru. My pond has a drain pipe behind the skimmer to drain off excess rainfall. The mini-nuggets fall down into the drain, and can plug it up. So, I fashioned a screen wire covering made out of hardware cloth, the same hardware cloth I used to use to make drain hole screens (before I switched to plastic). Well, the little pieces of bark would pile up against the screen. And so would the water! Oh, it still drained, slowly, but more and more pine bark would pile up, and the water level rose. Eventually, my pond flooded over. Held back by little pieces of bark.

if pine bark can cause a 6000 gallon pond to flood, I have no doubt it can stop up the drainage in a bonsai pot.
I believe that is why the percentage of pine bark and the shape and size of bark particles is so important for effective use. If particles of pine bark are similar in size and shape to other components and the organic content is limited to 5% overall than it does have some benefits in certain situations. Two I can think of is additional moisture retention and PH adjustment. I suspect promotion of mycrohyzae may be another.
Full disclaimer, I no longer use pine bark , but recognize that many do with success when the above limitations are considered. The main reason I discontinued the use was the difficulty obtaining satisfactory product and the amount of work sifting and breaking.
Easier to adapt the amount of akadama or kanuma for moisture retention and PH adjustment.
 

Wires_Guy_wires

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the issue I’m discussing here isn’t organic vs inorganic, it’s particle shape.
That's what I'm discussing too.

Again, if you can show me a piece of cardboard or relative-to-size chunk of wood washing down through a bowl of marbles, I'll believe you.
Or get yourself a bag of rice or beans and try to wash down some chopped onions to the bottom of a colander, without shaking the colander. The onions are more likely to move upwards as opposed to downwards. Unless you chop them so finely, that they'll pass through the colander as well; not an issue at all.

Also, if water hits a flat surface, like a horizontal piece of wood.. What would happen to the water? It'll flow off the sides, creating a gap facing downwards - if there are particles around it that are able to move - following the stream of the water. If the bark moves in that direction, it'll end up vertically. All 'follow the path of least resistance' comes into play and the bark will stay horizontal. Where it's suddenly packed between two layers of inorganic particles on both sides that keep it in place. It can't tumble over if there's no empty air pocket to fall in to. We try to prevent air pockets in bonsai as much as possible. The fact that the bark could've moved in the downwards facing gap to begin with, means there was an air pocket. That's two conditions that have to be met for a piece of bark to move to begin with.

We're not growing in bark alone. There's plenty of rocks in there too, they tend to keep things into place.
Two dimensional structures surrounded by two dimensional structures have the tendency to stack. If they're surrounded by three dimensional structures, stacking is very unlikely. Especially if the three dimensional particles are heavier than the two dimensional ones.

If you're comparing a water filled pond, littered with bark to a bonsai pot, you're forgetting the 70-80% pebbles that should surround the bark and you're replacing those pebbles with 100% water. That's not discussing particle shapes, it's discussing water flow and its effects on free floating two dimensional structures. That alone could be the title of a research paper, but it's a different subject. Bonsai soil is not water. The movement dynamic is entirely different.
I bet your filter is sucking in water straight from the pond, and it's not passing through a pebble bed (a three dimensional maze/matrix). Otherwise the pebbles would've stopped that bark from clogging the filter. It might be an idea to install such a contraption to prevent this from happening again in the future. I know those filter systems don't come cheap.
As a matter of fact, a well designed pond should have the pump behind such a feature simply to prevent these issues from happening. There will be other issues, like stacking on top of the contraption and eventually organic waste (if left long enough) will screw up the water flow. But it seems easier to scoop up a few pounds of pebbles with organic waste and hose those down, than to take apart a water filter and having to scoop the pond every time it rained. Waste water treatments have been doing it like this for over 30+ years. Here in Europe there is a growing community that do stuff like below for swimming pools, without chlorine. The 'aggregates' is what I mean with the pebble matrix or contraption/feature.
If you would have had a aggregate bed like below, the bark would still have stacked (a mix of two dimensional objects will likely stack), but it would've stacked on top of the aggregate instead of inside your filter. You could fix that with a shovel.

800.jpg

 
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