100% Pine Bark?

peh3

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To put it short: I repotted my small ~12cm chinese elm into rather fine 100% pine bark, did I do bad?

I had to repot my chinese elm spontaneously because I noticed that the soil started to grow mold. (No need to lecture me on overwatering, I got deceived by a dry surface. It was never repot before and the soil was totally clogged up.)
As I didn't have anything but some leftover orchid-soil laying around, which is basically just pine bark, I just used that.

So I broke down the pine bark to be smaller with my fingers, put some rough pieces at the bottom of the pot and it seemed to hold quite well after putting some dust at the baste of my small tree. (Big mistake, I already know...)
This happend about a week ago, the tree seems to do okay but I am wondering wether or not I did a good thing. When I look up bonsai soil, it seems like people always mix pine bark with other types of soil.
However I keep seeing people using 100% pumice or akadama or whatever else.

I don't know if I should worry or maybe even repot again, hope someone could give me their opinion on this. Thanks for any answer.
 

0soyoung

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Bark is a good substrate - high air filled porosity. Your choice of words "rather fine" makes me pucker. Like dust? Like peat? Like mulch?

Dusty/peat-like could be trouble. Small, medium, or even large bark for the landscape would be great for 3 - 4 years. You will need to secure the plant/tree in the pot OR add something less than an equal part of potting soil OR both, for a while. The risk of it not being secured is that wind tips the trunk in the pot, moving and damaging the roots (death can come quickly thereafter, especially if it happens as new growth is extending in spring).
 

Leo in N E Illinois

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Your elm is fairly small. Tree nurseries often use composted pine bark as 100% of their growing media. It is a good media for the ''growing out'' or increasing the size of a tree phase of becoming bonsai. This is when a seedling is being brought up in size to become ''pre-bonsai''. So there is nothing wrong with 100% bark. This mix will not work well in a bonsai pot, because the bonsai pot is too shallow. It works well in a nursery pot, a pot with significan diameter and depth.

Yes, dig your finger into the mix to determine if it is moist or dry. The surface can be deceiving.

I would not repot it again right away into ''bonsai mix'', I would wait until next year.
 

peh3

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The bark pieces were about 1 - 2,5cm, and I reduced their size to about 0,5 - 1cm. I basically just snapped them in half.
Thanks alot for warning me about the tree falling over, it is a bit wobbly right now but still quite firm, guess I'll put some stones on top to be safe.

I repot it into a larger bonsai pot with a big drainage hole. Why wouldn't this mix work well with shallow pots? Because it dries out too fast?
And I started to use a long toothpick to check how wet the inside is now, I hope that works as well.
 

0soyoung

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Your bark size is OK.

You will find that roots grow into the bark and become troublesome to remove. So repotting becomes very complicated, IMHO. But, it could work otherwise. Bark takes 3 to 5 years to decompose to the point that air-filled porosity vanishes. But you would likely repot in that period of time anyway.

Life in shallow pots is easier to manage with a granular, inorganic substrate. I use calcined clay sold in the U.S. under the brand name Turface. Diatomaceous earth is a good substrate as well and is sold by U.S. auto parts companies as an oil adsorbent (e.g. NAPA oil dry 8822, O'Reilly Optisorb). Similar stuff is available in Germany, I'm sure. Akadama is not required.
 

peh3

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I plan on getting one or two more trees to keep myself busy. Found out that I can get lava and pumice very cheap locally, which I plan on mixing with my leftover pine bark, should I not do that?
 

_#1_

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I tried almost 100% soil conditioner (decomposed pine barks) last summer on my newly purchased calamondin.

Scraped off the native soil around the perimeter of the rootball and mixed them with the pine barks. The tree doubles in size in a couple months I had it. It became top heavy and i had to strap it down with bungee cords.

I'm going to check how the roots look when I repot it this growing season.
 

sorce

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Found out that I can get lava and pumice very cheap locally, which I plan on mixing with my leftover pine bark,

Sounds best!

I just read something about cats using 100% bark for recovery....
Forget where....but they were good, legit.

However....Welcome to Crazy!

I'm on the fuck bark bus....
For that fact that roots do grow into it, and removal of bark equals removal of root!
No!

Sorce
 
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There is an excellent soil resource written by markyscot. It will answer most of your soil questions, like why bark is more difficult in a shallow pot. Paradoxically it is because it holds more water for the same volume. It will also give you a good starting point to evaluate what you need in your climate.
 

peh3

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There is an excellent soil resource written by markyscot.
Excellent indeed, thank you alot.
Very funny to see Seramis clay granule getting recommended, as I have read to avoid it for bonsai on multiple german bonsai and plant forums. But I figured that those people don't really have an idea of what they talk about... =)
 

Adamantium

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I'm on the fuck bark bus....
For that fact that roots do grow into it, and removal of bark equals removal of root!
No!
Sorce
Does that mean when you repot something that was in some portion of pine bark, you end up tearing roots off? Because the roots latch on, but don’t go through?
 

sorce

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Does that mean when you repot something that was in some portion of pine bark, you end up tearing roots off? Because the roots latch on, but don’t go through?

Latch on and go through....

You can leave em....

But some bonsai pots are more shallow than a piece of bark......

Bark is a pain in the ass no matter what, introducing it is foolish, as there are a number of things that can take its place without any of its downfalls.

Sorce
 

Adamantium

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Well, I feel dumb. I wanted a more acidic mix for my JMs, so I used 20-25% Douglas Fir bark... Now I’m wondering if I should just buy a bag of diatomaceous.

The mix I just got is 35% turface, 20% pumice, 25% scoria, 5% horticultural charcoal and 20-25% Douglas Fir bark. Dun dun dunnnnnnnn

*Smacks head*
 

JosephCooper

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I think your elm will be fine, just worried about the tree falling over since pine bark is really light compared do pumice.

Just pack it in A LOT.
 

0soyoung

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Well, I feel dumb. I wanted a more acidic mix for my JMs, so I used 20-25% Douglas Fir bark... Now I’m wondering if I should just buy a bag of diatomaceous.

The mix I just got is 35% turface, 20% pumice, 25% scoria, 5% horticultural charcoal and 20-25% Douglas Fir bark
You don't need to add anything to Turface to have a suitably acidic substrate for Japanese maples.
 

Leo in N E Illinois

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Well, I feel dumb. I wanted a more acidic mix for my JMs, so I used 20-25% Douglas Fir bark... Now I’m wondering if I should just buy a bag of diatomaceous.

The mix I just got is 35% turface, 20% pumice, 25% scoria, 5% horticultural charcoal and 20-25% Douglas Fir bark. Dun dun dunnnnnnnn

*Smacks head*

This mix is quite good. It could be improved if the Turface were omitted, and that portion replaced with either more pumice or equal particle size Diatomaceous Earth. DE is NOT a substitute for Turface. Turface is a calcined clay, made from clays that were derived from limestone and other native rock. Diatomaceous Earth is the fossilized remains of diatoms, almost entirely silicates. No limestone in its history. DE and Turface are chemically quite different in origin. Osoyoung and I politely disagree on the use of turface. There is a camp of BNut that feel turface is horrible, there is another camp that feel turface is great. Both can point to trees that were grown very well with their respective mix. So I am letting you know this controversy exists, but I do not want to re-ignite the ''Soil Wars'', There are ways to use Turface well. I have a history of not using turface well. The one component that is superior to all others is Pumice. This is the only one that if you said to me you used 100% pumice as your mix, I would say great.

Generally no single component is ideal. The best growing media seems to be a blend of 2 to 5 materials. Your turface, pumice, scoria, charcoal, fir bark blend is pretty common. If the pumice was 35 to 50% and the turface adjusted accordingly I would buy that. A 25% or less Turface mix has not caused me any problems, I have been quite happy with it at this level. When I switched away from 100% turface, this was how I used up the stockpile of turface I had, and the issues I had seen disappeared.

I disagree with the notion that bark is bad. Or I wasn't clear if you interpreted my comment about 100% bark being bad in a bonsai pot. A MIX, that includes bark particles the same diameter as the pumice and other particles is excellent. Bark does help bring pH down. It is an excellent additive to a mix for maples, azaleas, hornbeams, blueberries and most deciduous trees. This is the ''organic'' component most often used when seeking a mix with an organic component. Key is that the bark particles, and pumice particles are all in the same size range. The 100% bark used by nurseries has a very wide range of particle sizes. In a bonsai pot, the bark is low enough in percentage that the pumice and other inert ingredients will keep the tree stable. It is good in a mix, it is only bad when it is 100% of the potting media.
 

Leo in N E Illinois

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When repotting, if a root has grown through a piece of bark, or a clump of akadama or pumice or any component, don't automatically remove the root to get rid of the old media. If the majority of the old mix falls away, you do not have to cut off every bit of old media. You should not reduce the root system beyond your original plan. If that means some old media is carried over into the next pot - that is no problem. A little bit of the old mix won't hurt.
 
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