hitsware
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What is Reasoning Behing Fast Draining Soil for Bonsai?

What is the reasoning behind having
Bonsai soil so fast draining .......
Say opposed to 'potting soil' ...

tomc
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hitsware wrote:What is the reasoning behind having
Bonsai soil so fast draining .......
Say opposed to 'potting soil' ...
Trees breathe through their feet. Potting soil is in large part loess. It accepts too little air for trees, (or much of anything else IMO)

I had to kill about my first 200 trees learning the lesson of very fast draining soil.

Bonsai soil is, as summarised by my daughter; "a bag of rocks with a little bark mulch dragged through it".

I think she was about right.

If you persist growing bonsai, you'll end up with very fast draining soil around the feet of the trees that live.

Marsman
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Great answer, Tom.

Here's a good write-up on bonsai soils: [url=https://www.bonsai4me.com/Basics/Basics_Soils.html]AN INTRODUCTION TO BONSAI SOILS[/url]

tomc
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SFK has a thread on here about locally sourced Thai bonsai soil. While it sounds like the soil for his growing conditions and mine, may have only one thing in common. It is the need for very fast draining soil that admits enough air to roots.

moulman
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Trees will grow in solid hardpan - it is not about the looseness of the soil as much as it is about root rot. Some trees can tolerate constantly wet feet, but most can't.

kdodds
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moulman wrote:Trees will grow in solid hardpan - it is not about the looseness of the soil as much as it is about root rot. Some trees can tolerate constantly wet feet, but most can't.
Bingo! You can easily grow a Schefflera as a bonsai in potting soil, for instance, but not really a maple, not past a few years anyway.

tomc
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kdodds wrote:Bingo! You can easily grow a Schefflera as a bonsai in potting soil, for instance, but not really a maple, not past a few years anyway.
Don't tell any of my maples that. They'll get depressed. ;)

TomM
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Mine either. They continue to improve as the years go by. But then I do fertilize, and re-pot (change the bonsai soil), every few years. Don't we all?
:o

edit:

But wait - moulman said "in potting soil". Sorry, I misunderstood. I do not use potting soil for maples or any other established bonsai, just a little in the mix for some starter plants.

tomc
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Japan maples will do OK with just inert stone/calcined clay and bark mulch for soil, but sugar maples & celtis need need a taste of either loess or finished compost around their toes.

I use a too big (1/4" hardware cloth) screen for bottom holes, to prevent clogging. The addition of this sort of fines will also need the gardener to moderate spring time over watering (bronzed leaves).

Also hearty rhodies-azalea like their dirt pretty mucky.

hitsware
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Thanks for the replies....
I ask because I just lost a Christmas present
Bonsai that dried out.
It was doing so well (nice and green new growth)
It was outside and the weather had
been rainy but then dried out.
After only a couple of days (with my inattention)
I looked and it was shriveled ...... :(
There's an obvious lesson there.

Jalopy19
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I've been in Bonsai for about two years and agree on the fast draining soil. However, I was perplexed when I saw what I think was a "weed" zelcova (probably a siberian elm) growing out of a tiny crack next to a telephone pole in a parking lot. I thought "If that thing can grow there why do my trees ever die?!" (which they do occasionally). It seems apparent to me that this tree has next to no air circulation, but it seemed to be doing fairly well.

In any event I find I am more likely to kill my trees by under-watering them in the hot sun than by over-watering them in Kansas. Both of these things make me tend to use larger/deeper than traditional pots and soil which is about 60% organic and 40% inorganic (haydite or sifted diatomaceous earth) for most all of my trees.

However, the more experienced people I talk to all seem to agree that the more inorganic the better in almost all cases.

Well I suppose this turned into a bit of a random rant, but if anyone has any thoughts on it I'd be interested to hear them.

kdodds
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You're not really alone, but certainly in the minority. With care, organic mixes, mixed in, or even straight, in some cases, can work. Tradition, however, along with experience, says otherwise for MOST people. Now, if you've never tried mixing in potting soil, you can't really chime in and say that it's, hands down, just no good. Right? Well, sort of. For may, relying on the past experiences of other bonsai enthusiasts (some experts) and trusting in their advice and seeing for yourself what THEY'VE done, well, it's not hard to continue with those recommendations. For myself, I see no need in keeping certain trees in potting mix, or a mix of potting soil and bonsai soil, whatever works. But, from years ago dabbling experience, I can say that the "traditional" trees like maples and pines, really do not like to be in a pot of potting soil, not past a few years anyway. Besides, in nutrient rich soil like that, maples, IME, tend to want to grow more up than anything else, even when pruned. And, they tend to get a little too "leggy" for use as bonsai.

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Gnome
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Jalopy19,
However, I was perplexed when I saw what I think was a "weed" zelcova (probably a siberian elm) growing out of a tiny crack next to a telephone pole in a parking lot. I thought "If that thing can grow there why do my trees ever die?!" (which they do occasionally). It seems apparent to me that this tree has next to no air circulation, but it seemed to be doing fairly well.
It has to do, at least in part, with the way the the earth functions as opposed to soil in a pot. In short, the earth has a greater capacity to draw water away than the limited quantity of soil in a shallow pot does. Here is a link that has goes into more detail.

https://www.evergreengardenworks.com/earthpot.htm

Norm



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