Using Akadama and Kanuma
Posted: September 4th, 2009, 2:35 pm
I was just about to repot a JBP and thought I should wait until I can use my akadama
In the mean time I thought it was a good time to start discussing how we are going to use it.
Here are the details that Arthur gave us for it's use
KANUMA & AKADAMA
These two ‘soils’ are in fact Pumice and have excellent properties for plant growth. They are light and therefore easier for pot handling, but most importantly they have the following useful properties:
They drain perfectly if prepared correctly.
They allow air to be drawn into the mix when watered.
They maintain near perfect moisture retention for plant health.
They are granular in character and aid root/nebari development.
Akadama is Neutral and Kanuma slightly Acid.
The Akadama used for potting purposes is HARD Akadama; SOFT Akadama is not of any use for bonsai.
Both Akadama and Kanuma come in 4 grades:
Large
Medium
Fine
Super Fine (used mainly for smaller bonsai such as Shohin
and Mame, and cuttings)
If the 3-layer (ie large in the bottom ⅓, medium in the middle ⅓ and fine for the top ⅓) repotting system recommended by all Japanese Bonsai Masters and Growers is adopted, the resulting growth, particularly in the second year after repotting, is strong but controllable.
The Super Fine Grades of Akadama and Kanuma can be used for cuttings, either combined with River/Propagating Sand 50/50 or on their own.
IMPORTANT: PLEASE NOTE
After opening the bag to make up a mix, lightly sieve the
contents to remove and collect the dust which can then be used
for making Peat Muck as is done in Japan.
After repotting, the pot should be watered copiously until the
water runs out clear from the bottom of the pot.
Kanuma and Akadama can be re-used once or twice, making them
very economical; sieve them each time and water accordingly.
MIXES
In Japan it rains for the month of June (December in Australia) and the temperature is about 30°C; July (January) and up to 35°C with about 99% humidity. These mixes have worked very well in Japan for 100 yrs or so and if used correctly achieve wonderful results.
KANUMA (acid pH)
Used principally for acid-loving bonsai - Azaleas/Rhododendrons, Camellias, etc, Satsuki in particular.
Satsuki/Azaleas: 100% (In a dry summer climate such as South or Western Australia a little Sphagnum Moss may be added.)
Orchids: Kanuma 6 parts, Leaf Mould 2 parts, River Sand 2 parts.
Indoor Plants: Kanuma 3 parts, Akadama 4 parts, Leaf Mould 3 parts.
Bulbs: Kanuma 5 parts, Akadama 2 parts, Leaf Mould 3 parts.
HARD AKADAMA (neutral pH) Akadama can be made harder if baked in the sun.
Used for Coniferous and deciduous trees other than acid-loving plants.
Black Pine/White
Pine/Shimpaku: Akadama 7 parts, Coarse River Sand (CRS) 3 parts.
Red Pine: (1) Akadama 6 parts, CRS 2 parts, Japanese Black Soil or Coco Peat
2 parts. (Ordinary peat repels water if it dries out in the mix.)
Or: (2) Akadama 8 parts, CRS 2 parts.
Zelkova/Elms: Akadama 8 parts, CRS 2 parts.
Maples: Akadama 8 parts, Sphagnum Moss 1 part, CRS 1 part.
Australian Natives: This is currently an open field but Akadama has been used on
its own, mixed with Kanuma and/or gravel and other media to
remarkably good effect. Very strong healthy growth and good
flower production have been recorded to date.
NOTES: Sphagnum Moss should be prepared by drying and then rubbing through a
medium sieve to make even particles before adding to the mix.
If using River or Propagating Sand, sieve out the finest particles. Gravel of a
uniform/graded size could be used instead.
When repotting do not jab too hard with the chopstick as this will break the
granules down.
Large particles produce heavy root and heavy top growth while fine particles
produce fine roots and fine top growth - important for pines in particular and
any bonsai once the basic structure is established.
Following these simple instructions a perfect very open free-draining mix can be achieved - ideal for bonsai culture.

ARTHUR ROBINSON, March 2008
And here is a little added info from Susie who works with Arthur
I just want to pass on a little knowledge that I have, regarding the use of Akadama and Kanuma.
Please listen to how Arthur instructs you to use it. I have heard some bad stories that result from the improper use of it, from supposed experts. By all means experiment with different mixes, but follow Arthur's two golden rules:
1) Lightly sieve Akadama/Kanuma (if you over sieve it, you will end up with a pile of dust) and
2) After you have re-potted your tree - give it thorough watering - there are two reasons for this a) you are getting rid of all the remaining dust (so you don't clog up the bottom of your pot) and b) it ensures all the soil has been thoroughly soaked - if you want to see what I mean carry out the following experiment. In a clear well draining container (similar to a large plastic pot), fill with medium (in this experiment sizes does not matter) Kanuma, and water as you normally would - don't cheat. Then have a look at the sides of the container, you will see pockets of Kanuma that has not been wet.
Anyway enough from me, let us know how it goes - I wish you all the best with the shipment.
Susie
I found the same thing happening with a clear pot that I have fig cuttings in. It has alot of fine zeolite on the surface but It has made me wonder if all soil does the same? Anyway food for thought.
In the mean time I thought it was a good time to start discussing how we are going to use it.
Here are the details that Arthur gave us for it's use
KANUMA & AKADAMA
These two ‘soils’ are in fact Pumice and have excellent properties for plant growth. They are light and therefore easier for pot handling, but most importantly they have the following useful properties:
They drain perfectly if prepared correctly.
They allow air to be drawn into the mix when watered.
They maintain near perfect moisture retention for plant health.
They are granular in character and aid root/nebari development.
Akadama is Neutral and Kanuma slightly Acid.
The Akadama used for potting purposes is HARD Akadama; SOFT Akadama is not of any use for bonsai.
Both Akadama and Kanuma come in 4 grades:
Large
Medium
Fine
Super Fine (used mainly for smaller bonsai such as Shohin
and Mame, and cuttings)
If the 3-layer (ie large in the bottom ⅓, medium in the middle ⅓ and fine for the top ⅓) repotting system recommended by all Japanese Bonsai Masters and Growers is adopted, the resulting growth, particularly in the second year after repotting, is strong but controllable.
The Super Fine Grades of Akadama and Kanuma can be used for cuttings, either combined with River/Propagating Sand 50/50 or on their own.
IMPORTANT: PLEASE NOTE
After opening the bag to make up a mix, lightly sieve the
contents to remove and collect the dust which can then be used
for making Peat Muck as is done in Japan.
After repotting, the pot should be watered copiously until the
water runs out clear from the bottom of the pot.
Kanuma and Akadama can be re-used once or twice, making them
very economical; sieve them each time and water accordingly.
MIXES
In Japan it rains for the month of June (December in Australia) and the temperature is about 30°C; July (January) and up to 35°C with about 99% humidity. These mixes have worked very well in Japan for 100 yrs or so and if used correctly achieve wonderful results.
KANUMA (acid pH)
Used principally for acid-loving bonsai - Azaleas/Rhododendrons, Camellias, etc, Satsuki in particular.
Satsuki/Azaleas: 100% (In a dry summer climate such as South or Western Australia a little Sphagnum Moss may be added.)
Orchids: Kanuma 6 parts, Leaf Mould 2 parts, River Sand 2 parts.
Indoor Plants: Kanuma 3 parts, Akadama 4 parts, Leaf Mould 3 parts.
Bulbs: Kanuma 5 parts, Akadama 2 parts, Leaf Mould 3 parts.
HARD AKADAMA (neutral pH) Akadama can be made harder if baked in the sun.
Used for Coniferous and deciduous trees other than acid-loving plants.
Black Pine/White
Pine/Shimpaku: Akadama 7 parts, Coarse River Sand (CRS) 3 parts.
Red Pine: (1) Akadama 6 parts, CRS 2 parts, Japanese Black Soil or Coco Peat
2 parts. (Ordinary peat repels water if it dries out in the mix.)
Or: (2) Akadama 8 parts, CRS 2 parts.
Zelkova/Elms: Akadama 8 parts, CRS 2 parts.
Maples: Akadama 8 parts, Sphagnum Moss 1 part, CRS 1 part.
Australian Natives: This is currently an open field but Akadama has been used on
its own, mixed with Kanuma and/or gravel and other media to
remarkably good effect. Very strong healthy growth and good
flower production have been recorded to date.
NOTES: Sphagnum Moss should be prepared by drying and then rubbing through a
medium sieve to make even particles before adding to the mix.
If using River or Propagating Sand, sieve out the finest particles. Gravel of a
uniform/graded size could be used instead.
When repotting do not jab too hard with the chopstick as this will break the
granules down.
Large particles produce heavy root and heavy top growth while fine particles
produce fine roots and fine top growth - important for pines in particular and
any bonsai once the basic structure is established.
Following these simple instructions a perfect very open free-draining mix can be achieved - ideal for bonsai culture.

ARTHUR ROBINSON, March 2008
And here is a little added info from Susie who works with Arthur
I just want to pass on a little knowledge that I have, regarding the use of Akadama and Kanuma.
Please listen to how Arthur instructs you to use it. I have heard some bad stories that result from the improper use of it, from supposed experts. By all means experiment with different mixes, but follow Arthur's two golden rules:
1) Lightly sieve Akadama/Kanuma (if you over sieve it, you will end up with a pile of dust) and
2) After you have re-potted your tree - give it thorough watering - there are two reasons for this a) you are getting rid of all the remaining dust (so you don't clog up the bottom of your pot) and b) it ensures all the soil has been thoroughly soaked - if you want to see what I mean carry out the following experiment. In a clear well draining container (similar to a large plastic pot), fill with medium (in this experiment sizes does not matter) Kanuma, and water as you normally would - don't cheat. Then have a look at the sides of the container, you will see pockets of Kanuma that has not been wet.
Anyway enough from me, let us know how it goes - I wish you all the best with the shipment.
Susie
I found the same thing happening with a clear pot that I have fig cuttings in. It has alot of fine zeolite on the surface but It has made me wonder if all soil does the same? Anyway food for thought.
Pup
