The Satsuki Society of Australasia Inc.
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:

  1. They drain perfectly if prepared correctly.
  2. They allow air to be drawn into the mix when watered.
  3. They maintain near perfect moisture retention for plant health.
  4. 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:

  1. Large
  2. Medium
  3. Fine
  4. 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.



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.


Potting Mixes

In Japan it rains for the month of June (December in Australia) and the temperature is about 30°C; July (January) is around 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.


100% (In a dry summer climate such as South or Western Australia a little Sphagnum Moss may be added.)


Kanuma 6 parts, Leaf Mould 2 parts, River Sand 2 parts.

Indoor Plants:

Kanuma 3 parts, Akadama 4 parts, Leaf Mould 3 parts.


Kanuma 5 parts, Akadama 2 parts, Leaf Mould 3 parts.

HARD AKADAMA (neutral pH) 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.


Akadama 8 parts, CRS 2 parts.


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.


CRS = ( Coarse River Sand)

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.

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