Akadama...My Experience

[Nybonsai12]

Getting ready to drop into another soil thread

 

[Bnana]

Throughout the years, the fine root growth that is inside the compacted broken down akadama is essential to the fine ramification of the branches.

You hear this story often but how would that work? What's the physiological processes? It just doesn't make sense to me that finer soils particles would result in smaller more ramified branches.

Granite is not porous so it's not a good component of bonsai soil.

 

[Adair M]

Akadama is a mined product, and the quality varies from mine to mine. The very best akadama mines were destroyed by the tsunami that hit Japan several years ago. So, for a while, all the akadama was inferior quality. The quality is getting better now.

Akadama absorbs water, and holds water whereas pumice and lava don’t. But, that makes it susceptible to the freeze/thaw problem. If your pot continues to drain well, you have no problem.

Akadama works well as a bonsai soil component because when you repot using it, the soil structure is very coarse. This encourages rapid root growth, which is what you want since you cut off roots in the repotting process. However, for long term bonsai maintenance, the goal is to constrain root growth. More constrained roots help the tree develop shorter internodes, smaller leaves, and more ramification. So, for your old, developed bonsai, akadama is ideal: You re-establish the root system quickly, but as the akadama breaks down, it slows the growth of the tree, helping to maintain and develop fine twigs and ramification. If instead you are working with young material that You want to have rapid, coarse growth, then using some other component might suit your needs better because a coarse soil structure will promote coarse top growth, which can “put on wood” faster. It all depends upon your goals.

There is no other soil component that acts like akadama. It’s a very valuable tool, if used properly. There are sources of akadama in other parts of the world, not just in Japan. But to my knowledge, no one mines it, except for the Japanese.

 

[Adair M]

You hear this story often but how would that work? What's the physiological processes? It just doesn't make sense to me that finer soils particles would result in smaller more ramified branches.

Granite is not porous so it's not a good component of bonsai soil.

The growing top growth buds and the roots communicate with each other via hormone flow, up and down the cambium. The growing buds send auxin down to the roots to tell them to grow, and the roots send a hormone back up to let the buds know if conditions are good. The rapidly growing roots send more hormone back up to the buds if they’re going well, and less if they’re constrained. This process has the effect of keeping the top growth mirroring the root growth.

 

[Adair M]

Earlier in post #43, I said that if you want rapid growth, to use something else other than akadama. Pumice is ideal for that. It doesn’t break down, and it stays coarse. It promotes rapid root growth. Most collectors getting yamadori out of the mountains use pumice as their soil medium for their newly collected trees because they have drastically reduced the roots in the collection process, and want the trees to produce new roots quickly. They don’t care about coarse top growth, they want new roots to ensure the tree’s survival. Since it doesn’t hold water, they will have to water more frequently.

 

[Bnana]

The rapidly growing roots send more hormone back up to the buds if they’re going well, and less if they’re constrained. This process has the effect of keeping the top growth mirroring the root growth.

Sure, but that's about growth, not about ramification.
Poor/reduced root growth gives poor/reduced shoot growth. But I can achieve that by reducing fertilization as well.
This still does not explain why finer soil material would result in finer top growth.

 

[penumbra]

I think Michael Hagedorn in his book Bonsaï Heresy explains it well about the usage of Akadama.

He mentions that the eventual breakdown of akadama in the rootball of old trees is exactly what the Japanese are looking for. Throughout the years, the fine root growth that is inside the compacted broken down akadama is essential to the fine ramification of the branches. The compacted akadama rootball is never touched eventually after many years.

At the moment in the west, I do not know if there is a substitute for akadama where the long term goal or function is for maintaining healthy fine root growth for decades in the root core.

I am not sure of the pertinence of referencing my post, that is the matter at hand, in your response. I have read Bonsai Heresy and liked it very much, and what Mr Hagedorn says has relevance only to the people who use akadama in the way specified. My post was clearly not a condemnation of the use of this one of many bonsai substrates. It was just a statement of fact that not everyone uses akadama or has a desire to do so and that many who do use it don't use it with a proper understanding of its intended use.

 

[penumbra]

Akadama is a mined product, and the quality varies from mine to mine. The very best akadama mines were destroyed by the tsunami that hit Japan several years ago. So, for a while, all the akadama was inferior quality. The quality is getting better now.

Akadama absorbs water, and holds water whereas pumice and lava don’t. But, that makes it susceptible to the freeze/thaw problem. If your pot continues to drain well, you have no problem.

Pumice and lava are also mined and have a great variance of quality, but perhaps not to as great a degree as akadama. But pumice does absorb water with variance according to its source, while lava typically holds much less.

 

[Mike Corazzi]

I had such a bad experience with akadama some years back that now I ...cheat.
I still mix pumice, lava, and hyuga ...but... for the akadama component I use a professional mix.
That way the aka is already containing more lava, pumice and hyuga (in the "mix" I buy.)

Mixed mix, if you will.

 

[Lorax7]

Getting ready to drop into another soil thread
View attachment 426795

 

[Adair M]

Sure, but that's about growth, not about ramification.
Poor/reduced root growth gives poor/reduced shoot growth. But I can achieve that by reducing fertilization as well.
This still does not explain why finer soil material would result in finer top growth.

A coarse, open soil allows the roots to extend forward into large open spaces between particles easily. It is when the root tips hit something solid that they have to branch out to devise a way to get around the rock or pebble. This action in the roots is reflected in the way the top grows. And sure, fertilization plays a part as well.

But, if you want lots of ramification, use smaller soil particles. You want more rank growth, use coarse soil.

 

[Adair M]

Pumice and lava are also mined and have a great variance of quality, but perhaps not to as great a degree as akadama. But pumice does absorb water with variance according to its source, while lava typically holds much less.

All three are Volcanic. Lava is basically rock. Pumice is basically glass, but it’s not solid. Both pumice and lava have air pockets which make the material lighter in weight, pumice more so than lava. Akadama, on the other hand, is clay. And it can absorb water, whereas neither pumice nor lava can. They can contain a bit of water in the pores of their surfaces, but they don’t soften when wet like akadama does.

 

[Adair M]

I had such a bad experience with akadama some years back that now I ...cheat.
I still mix pumice, lava, and hyuga ...but... for the akadama component I use a professional mix.
That way the aka is already containing more lava, pumice and hyuga (in the "mix" I buy.)

Mixed mix, if you will.

I find that the pre-mixed bonsai soils like “Clay King” and Aoki have a higher proportion of Akadama than I prefer, so I add pumice to them. For Aoki, for example I make a mix of 3 parts Aoki and 1 part pumice. That works well for me in my climate.

However, since it is so hot and dry where you are, you should be using more akadama where you are to hold more water in your soil.

 

[Bnana]

A coarse, open soil allows the roots to extend forward into large open spaces between particles easily. It is when the root tips hit something solid that they have to branch out to devise a way to get around the rock or pebble. This action in the roots is reflected in the way the top grows.

The first part makes sense, that this will affect root structure I can understand. The last sentence doesn't make sense to me. Why would that be the case? I read this over and over as some kind of truism. But without any explanation or evidence what so ever.

 

[Adair M]

The first part makes sense, that this will affect root structure I can understand. The last sentence doesn't make sense to me. Why would that be the case? I read this over and over as some kind of truism. But without any explanation or evidence what so ever.

The evidence is mature bonsai. Old established bonsai that dont get repotted very often slow their top growth. They produce smaller leaves.

But, when you repot them, now they have new, fresh soil. They tend to put on top growth that is stronger, produce larger leaves, have longer internodes! Then, after a year or two, when they have refilled the voids with roots, the top growth slows, the leaves shrink, the internodes shorten.

Once you have the benefit of having years of experience, you will see it for yourself. I’ve been doing bonsai for over 50 years. I have seen this effect many, many times.

 

[badatusernames]

A coarse, open soil allows the roots to extend forward into large open spaces between particles easily. It is when the root tips hit something solid that they have to branch out to devise a way to get around the rock or pebble. This action in the roots is reflected in the way the top grows. And sure, fertilization plays a part as well.

But, if you want lots of ramification, use smaller soil particles. You want more rank growth, use coarse soil.

so what size do you use for say kifu sized trees in refinement? Medium or small?

 

[Adair M]

so what size do you use for say kifu sized trees in refinement? Medium or small?

Medium. you “could” use the small if you wanted. I tend to use the small for shohin. For a deciduous tree, I might use small, and for a conifer, I’d use medium. Because small holds more water, and those leaves need more water.

 

[yashu]

I’m in zone 5a and had the same breakdown from cold. I don’t use akadama anymore. As noted there was some intact particles left but no more than 25% was intact. Attached is my after/before photos. This is just my experience, ymmv.

 

[Leo in N E Illinois]

Over my 40+ years of doing bonsai I have tried Akadama many times, it is a crap shoot. I am in the USA. I can NOT read Japanese. I have no clue what quality material I am buying and 9 times out of 10 the vendor I am buying from has even less knowledge about the stuff than I do.

Good news, when Akadama breaks down into a sand like product, it usually continues to drain well, even for 2 or 3 years after the initial breaking down. So emergency repotting is not usually necessary.

I would get a couple of "good bags" of Akadama, then run into a bad bag, then I would boycott the use of Akadama for 5 or 6 years. There are plenty of soil mixtures that work "pretty good" that do not require the use of obscure Japanese dirt.

Pumice is the single most useful potting media component that anyone has ever invented. It is near perfect. It can even be used at 100% as a solo component media, which pretty much nothing else can be used that way. If you use an organic fertilizer like rapeseed cake or cotton seed cake or sugar cane bagasse, with a pumice based mix, the organics quickly make a pretty natural "soil" that supports mycorrhiza and a whole microbiome. Pumice as an additive or a base ingredient improves all other potting media blends, including Akadama.

Pumice 50% to 75 % blended with diatomaceous earth, especially if you can get a particle size DE to match the particle size of the pumice, makes a nice non-akadama based blend that grows a damn nice root system. Especially with dry seaweed powder or rapeseed cake as the supplemental fertilizer. Lava can replace a significant portion of the pumice if this mix is too wet for your climate and watering conditions.

But like I said, I would boycott Akadama for 5 or 6 years, then someone would swear they have the "best brand ever" and I'd get another bag. Lately I have Hidden Gardens on the South Side of Chicago and Ron Fortman west of Milwaukee both carrying excellent grades of Akadama for me. So I have been using it in a 1:1:1 mix lava, pumice, akadama. So right now I am using it.

And I will add, I have found Kanuma to be more consistent from bag to bag. I use Kanuma for my azalea, an have been known to use the kanuma for my pines when I have run out of Akadama. Kanuma looks funny under a pine, but the pines seem to grow the same. So I guess it isn't wildly different than Akadama. It seems to hold its shape longer. More winters than Akadama.

But I do want to say, there is nothing magical about "Japanese Dirt"

 

[Adair M]

One thing that hardly ever gets mentioned is annual maintenance. Each fall, the top 1/2 to 3/4 inch of old soil is scraped off and replaced with fresh bonsai mix. This removes weeds, old fertilizer, broken drown soil, etc. Do this for trees you don’t plan to repot the following spring. This practice is called “soji”.