The Bonsai Soil Argument

[Rivian]

Background info: Pumice is great, but floats (upside: is light). Used neat, probably best to let moss cover the surface to maintain moisture, per DSD among others. Lava probably looks better imo but is heavy (upside: doesnt float) and may contain plant damaging levels of boron. Generally said pumice produces best growth among these two at least. They can probably be recycled near infinitely
(not the soft English pumice I guess), in contrast to akadama.

Been impressed with high quality peat that some bought plants arrived in (health, water holding...). Assuming its the properly harvested stuff and thats why the nurseries love it, not some fake.

Big JM in fully P/L and loves it, better than fake peat at least. Rooted through all soil within 6 months I think.
Ironically not too happy with growth of my pomes in that mix, might go for high organic content next year, and quality of it.
But these arent Bonsai, just potted.
I think Walter Pall sometimes used peat chunks in mixes, so youd still get good airflow through the substrate between the chunks.

My aim for big bonsai atm: pure pumice (+ biochar for CEC?), moss covered.

 

[Bonsai Nut]

Background info: Pumice is great, but floats (upside: is light).

I have never owned a pumice that floats. Are you thinking perlite?

...and as to the subject of this thread, it gets back to my initial post in the "how to be a successful bonsai beginner" thread. Repeat other peoples' successes, not their failures. Choose your favorite bonsai artist and try to emulate what they do... not what they don't do.

If akadama and pumice cost less than potting soil, we wouldn't be having these conversations. I get it - soil components can be expensive - and I'll be the first to say that I am always looking for ways to save money. But be honest with yourself about why you are doing what you are doing.

And let's make sure we are talking about the same subject. We aren't talking about propagation mixes, or what you put your 1 year-old seedlings in. We're talking about bonsai mixes for trees in pots. Many organic mixes will perform well for a month or two, or even half a year... until the organic components start to break down, the soil compacts, and all your tree roots die. There are truly thousands of threads on this site about people coming here for help, and the first thing you see is a weak tree with stressed foliage, planted in compacted organic soil. And almost every time the advice is the same - repot and get it out of that bad soil. People will lose a tree they bought for $200 because they are hesitant to spend $5 on enough inorganic soil to repot it in.

 

[Rivian]

I have never owned a pumice that floats. Are you thinking perlite?

Nah I know the difference. Pumice does get washed up on some beaches, doesnt it? May not exactly float (some does) if you throw a handful into still water, but when watering plants quickly it gets washed up and away whereas the Lava sits in place.

 

[Bonsai Nut]

Nah I know the difference. Pumice does get washed up on some beaches, doesnt it? May not exactly float (some does) if you throw a handful into still water, but when watering plants quickly it gets washed up and away whereas the Lava sits in place.

There is big difference between fresh pumice from volcanoes, and the mined pumice that we use for horticultural purposes. Mined pumice will have greater or lesser density depending where you get it, but I have never had pumice wash out of a soil mix. I plant some of my trees in 100% pumice and though yes, it tends to be lighter than lava, everything is relative. Certainly in a 3 part mix of pumice, lava, akadama, I have never had pumice separate out of the mix. The biggest issue I have with 3 part mixes is that all akadama is not the same, and some breaks down very quickly into clay/dust.

And just to make sure I wasn't being gas-lit, I went down and took a cup of my Hyuga pumice (which is lighter than my west coast/oregon pumice), dumped it into a 5 gallon bucket that had 6" of water in it, and watched it go straight to the bottom like lead.

 

[Zac]

Non of my tree's are "bonsai" they are all pre-bonsai or cuttings being grown to eventually be bonsai. My tropicals are in heavily organic soil but do have inorganic aggregates mixed in. And my others are also in organic mixes but these have more of the inorganic aggregates mixed in. Only a couple are in bonsai pots. I work long hours so can't water trees multiple times during the day. In the summer I water twice a day on hottest driest days. Once in morning then again late evening when I get home. If I used total inorganic mix I would loose trees to drying out. Sometimes they are so dry when I get home that I have to soak them because the organics become hydrophobic. I think this is probably the biggest problem with organics. People think they are watering their trees but really they aren't water just wetting top and running off. I recently got some young JBP's and they will be in mostly inorganic soil with just some bark for the mycorrhizal. When my tree's make it to the refinement stage I'll use the Japanese bonsai soils.

 

[Glaucus]

Trees and plants that are non-bonsai, prebonsai, seedlings, cuttings, air layers etc etc they almost always grow better in a mixture where some 'soil' aka peat or peat substitute is added. It is also cheaper and easier to maintain those plants.
Those plants have deeper pots, which provides more gravity pull to change the water table aka capillary effect, draining out water and bringing in air. And you are likely to uppot them if they have grown a fair amount. And usually these plants grow more rapidly. The organic matter will decompose as the roots grow, and you can uppot the plant in new fresh peat-based mix The root wall will therefore stay relatively airy and doesn't need to be bare rooted. Uppotting can be yearly or biannually.

But when you go to a bonsai pot, you want the tree to be in that pot for 3 to 5 years, then things are very different. The roots will fill the pot and then the tree will be in some status quo. And the goal is to delay having to repot the tree. You only do so when your akadama is falling apart.
If you were to use *soil* in a bonsai pot and you leave it that way for years, it will decay and compact in the bottom of the pot. 2 or 3 years in. And you will have less air in your roots and get into troubles eventually.

 

[Attmos]

It works better to use Google search and include "bonsainut" as a term. "bonsai soil bonsainut"

That's a good suggestion.

 

[Attmos]

I have never owned a pumice that floats. Are you thinking perlite?

...and as to the subject of this thread, it gets back to my initial post in the "how to be a successful bonsai beginner" thread. Repeat other peoples' successes, not their failures. Choose your favorite bonsai artist and try to emulate what they do... not what they don't do.

If akadama and pumice cost less than potting soil, we wouldn't be having these conversations. I get it - soil components can be expensive - and I'll be the first to say that I am always looking for ways to save money. But be honest with yourself about why you are doing what you are doing.

And let's make sure we are talking about the same subject. We aren't talking about propagation mixes, or what you put your 1 year-old seedlings in. We're talking about bonsai mixes for trees in pots. Many organic mixes will perform well for a month or two, or even half a year... until the organic components start to break down, the soil compacts, and all your tree roots die. There are truly thousands of threads on this site about people coming here for help, and the first thing you see is a weak tree with stressed foliage, planted in compacted organic soil. And almost every time the advice is the same - repot and get it out of that bad soil. People will lose a tree they bought for $200 because they are hesitant to spend $5 on enough inorganic soil to repot it in.

It's true, the cost of these products is definitely why I want to fully explore what else is available, and how those products act as a substrate. I get your point though and If I end up having to pay for the good stuff, I will... I just won't be able to raise as many trees.

 

[Attmos]

Trees and plants that are non-bonsai, prebonsai, seedlings, cuttings, air layers etc etc they almost always grow better in a mixture where some 'soil' aka peat or peat substitute is added. It is also cheaper and easier to maintain those plants.
Those plants have deeper pots, which provides more gravity pull to change the water table aka capillary effect, draining out water and bringing in air. And you are likely to uppot them if they have grown a fair amount. And usually these plants grow more rapidly. The organic matter will decompose as the roots grow, and you can uppot the plant in new fresh peat-based mix The root wall will therefore stay relatively airy and doesn't need to be bare rooted. Uppotting can be yearly or biannually.

But when you go to a bonsai pot, you want the tree to be in that pot for 3 to 5 years, then things are very different. The roots will fill the pot and then the tree will be in some status quo. And the goal is to delay having to repot the tree. You only do so when your akadama is falling apart.
If you were to use *soil* in a bonsai pot and you leave it that way for years, it will decay and compact in the bottom of the pot. 2 or 3 years in. And you will have less air in your roots and get into troubles eventually.

So, I guess, by the time you absolutely need the inorganic mix, the pot size doesn't require excessive amounts of it....?
That makes buying it sound less daunting, lol.

 

[Paradox]

I use what works for me. That is an open soil mix where I can control the moisture in the pot easier than organic/soil based mixes.

If a soil based mix works for you go for it. I'll stick with what works for me

 

[cmeg1]

I used to totally disregard ph of the nutrient.And when ph was good some of the peat based stuff would decompose to a very acidic form.
Then if no air ,the bacteria or pathogens such as root rot and such will ignite as they are already present everywhere!

An open mix wins in the end and a propor ph of nutrient solution……. when your soil gets too hot, it needs to be open cause if no air gets there the root rot ignites because the spores or whatever causes these things is already present everywhere.

Been there done this volcanic open whatever…. Needs to be open because when it gets very warm, the rots will happen. There’s no way to stop it. The pH instantly goes off at the root contact from the root rot.

I have monitored these conditions and was able to diagnose because it would only affect certain plants and not the entire outcome of plants that means it was fungus. A nutrient deficiency from fertilizer would be all plants not just one plant so it was soil mixture to dense and too warm

The best plants I’ve ever grown are in straight perlite…
As long as you can keep them moist!!!

 

[littletreefarmer]

Aren't there about 1,000 threads on this already? Why we gotta always be reinventing the wheel on proven soil media instead of focusing on the trees? Boon told me a few month back that "when new students come to my garden, if they don't want to use my soil mix I tell them to leave. I can't teach them." It's a basic fundamental.

Buy the correct tools and supplies for the type and level of work you want to perform. If you want to grow houseplants, use peat or whatever. If you want to grow bonsai, use bonsai soil. I get the price argument, but budget for what you need. You wouldn't adopt 36 cats if you'd couldn't afford to feed them. Likewise, only keep the amount of trees that you can house and feed.

 

[rockm]

IMO This argument comes up because some people want to skimp on soil. Same thing that drives the “ bonsai pots are too expensive” threads. Skimp if you want cut corners too. There can be consequences.

Peat and bark are used by nurseries for potted trees because ITS LESS EXPENSIVE than actual bonsai soil. It’s also a lot lighter cutting shipping costs. Peat and bark based soils at nurseries ARE TEMPORARY the tree growing in it is meant to be purchased and planted IN SOMETHING ELSE BETTER.

 

[Attmos]

Aren't there about 1,000 threads on this already? Why we gotta always be reinventing the wheel on proven soil media instead of focusing on the trees? Boon told me a few month back that "when new students come to my garden, if they don't want to use my soil mix I tell them to leave. I can't teach them." It's a basic fundamental.

Buy the correct tools and supplies for the type and level of work you want to perform. If you want to grow houseplants, use peat or whatever. If you want to grow bonsai, use bonsai soil. I get the price argument, but budget for what you need. You wouldn't adopt 36 cats if you'd couldn't afford to feed them. Likewise, only keep the amount of trees that you can house and feed.

Apologies, and you're right, I probably shouldn't have started this post.
I also forgot to make the distinction between developing trees/pre-bonsai... and fully developed bonsai.

As has been said, the inorganic mix is obviously very important for the survival of a fully developed bonsai, but it sounds like developing trees might benefit from other types of substrate due to pot size, environment, etc...

I guess after having read a bunch of them, I wanted to talk about it to make sure I'm understanding correctly.
Normally I just ask question on other posts... I'll just do that in the future.

 

[Glaucus]

OP already said he asked this question because of the price of Japanese bonsai substrate. But substrate doesn't have to be that much more expensive than peat. Perlite is about the same price as a premium potting mix per liter.
In Japan, a bag of 14 liter akadama is about 6 USD. The price is not because it is substrate, but because it has to be imported by a small operation bonsai shop from Japan specifically for bonsai hobbyists.
Substrate for horticulture can be delved in many many parts of the world. We have seen people try akadama alternatives from other parts of the world. But the bonsai community often hates it and reject it.

Just this spring, Ryan Neil went on a monologue at The Trophy about how it was serendipity that bonsai developed culturally in the same country that is the only place in the world geologically with substrate deposits that allow for high quality bonsai.
Citing some factoids about pore size and electron-microscopy (and getting a size of pores vs roots wrong by order of magnitude off by about 1000, I believe).
For a deep dive, people should search what @markyscott has posted about akadama and the geology and mineralogy on bnut. As well as his Introductory Soil Physics

Thread 'Introductory soil physics'

Oct 3, 2016

Questions about soil physics come up all the time and I find that I repeat myself a lot on this topic. I'm going to try and write a reference for folks to refer to on this topic. I'm expressly NOT going to offer you any advice on what soil you should use in your garden, whether you should use organics or inorganics, or anything on that line (that's where these soil threads go south). Instead, What I'm going to do is offer some basic information on which you might base your own choices. I'll try to do this at a high level, but this is related to my profession, so it's easy for me to go...

• markyscott
• Replies: 330
• Forum: Soil, ferts, and chems (insecticides/fungicides)

• 
• 

Introductory Soil Physics - Updates

The most popular Bonsai Community in the WORLD!

www.bonsainut.com

Also, peat is not used in the nursery industry because it is cheap and 'good enough' and 'the plant goes into the garden soil anyway'. Nursery industry plants do way better in pots with peat than they do in almost anyone's garden.
Nursery industry plants need to be top quality first and foremost. Only then comes price. If all that mattered is it being cheap, nurseries wouldn't use premium brand potting mixes, but just recycle old stuff or dig up random dirt.
They don't because they can't grow quality plants in that. The bottleneck of the nursery industry is labour first, and technology like greenhouses, automation, water filtering second.
People have tried to experiment with non-peat alternatives mostly for environmental reasons, and often the quality is just less and nurseries keep using peat.
So the idea that a plant does marginally ok in a nursery container with peat or pine, but that it doesn't matter because it will go into very nice garden soil and then the plant will develop the quality desired, is just not true here in the Netherlands.

Yes, plants may do better if grown in hydroponics or perlite. But then the watering and fertilizer changes.

The main point indeed being that you shouldn't try to save a few bucks on soil vs substrate when repotting your pricy Japanese import bonsai, or decade-long project. But on the other side of the coin, there is definitely potting mixes with organic components, in bonsai pots, that can work very well. It also depends on species, climate, watering and fertilizer regimes, etc.

The Japanese also did bonsai before they figured out that for them akadama was best.

 

[Attmos]

IMO This argument comes up because some people want to skimp on soil. Same thing that drives the “ bonsai pots are too expensive” threads. Skimp if you want cut corners too. There can be consequences.

Peat and bark are used by nurseries for potted trees because ITS LESS EXPENSIVE than actual bonsai soil. It’s also a lot lighter cutting shipping costs. Peat and bark based soils at nurseries ARE TEMPORARY the tree growing in it is meant to be purchased and planted IN SOMETHING ELSE BETTER.

You're absolutely right, it has to do with the cost. I was just telling Bonsai Nut that I'll go ahead and buy the right stuff, I just won't be able to raise as many trees.

 

[PA_Penjing]

bonsai travellers in China comment that the public Penjing display trees mostly seem to be planted in garden soil - or at very least, a very fine particle potting soil.

I think about this a lot. I used to follow a lot of chinese youtubers from penjing nurseries and they used clay soil from the ground, VERY lightly ammended sometimes with small sized gravel collected from streams. And you don't have to take my word for it, open one of the many penjing books in circulation and you will notice "national treasure trees" are clearly growing in light brown looking clay. Not particles or anythign but level soild looking dried mud surfaces. I know nothing about the soil types of china and I'm sure they are very selective about what they use (maybe?) but it just goes to show there's more than a few ways to do it. I keep most of my trees in pumice and akadama because I can get it for free. But i've certainly noticed that some trees like american elm and dawn redwood seem better off in potting soil. GRANTED I don't have those trees in super shallow pots, that could maybe change things. I dont know

 

[WNC Bonsai]

I just won't be able to raise as many trees.

Probably a good thing!

 

[Nera]

I'm still new in my bonsai journey, so reading the responses here with interest. Non-organic works really well for my own trees. Most of the potting soils offered where I am are not good quality, and yes I could put together a more organic mix of my own, but I'm not generally big on organic and also not convinced it would be superior.

 

[Rivian]

As far as what nurseries use, Ive seen a huge range in quality. Small potted "laymans bonsai" in quality peat and plastic pot (garden center), others from a JM focused place in wood chips that turn to sludge eventually, or a poor, fine garden soil (b&b). People who know better but presumably do cut costs that way, why else do it?
Conifers in pine bark are common, with slow release fert sprinkled in, or low quality peat/ perlite mix. It seems to work well enough.

I used pine bark (7-15mm) extensively for a while but dont like it much anymore, turns kinda sludgy smeary after a couple years as well, though nowhere near as much as wood chips.

Do like 0(2?)-8mm pine bark in mixes for azaleas. But have recently found a good peat for them as well, works better neat than any mix along traditional bonsai lines Ive ever given them.