Kanuma Japanese Pumice 17L. (Popular for Bonsai and other plants that enjoy a higher PH value)

Also popular for Azaleas, Camelias, Cacti, Succulents and other plants.

Kanuma is in fact a form of volcanic soil (Pumice) mined exclusively in Japan and has excellent properties for plant growth. Kanuma is light in weight and therefore easier for pot handling, but most importantly they have the following useful properties:

Drains perfectly if prepared correctly (see below).
Allows air to be drawn into the mix when watered.
Maintains near-perfect moisture retention for plant health.
Are granular in character and aid root/nebari development.
Allows greater control over fertilisers in the potting medium.

Kanuma is slightly Acidic and thus is ideal for Azaleas, Camelias and other plants that enjoy a higher PH value.

Kanuma used for bonsai potting purposes in Australia comes in 4 grades or grain size:

Size Guide:

SuperSmall Kanuma 1-2mm – 17L Bag (Used mainly for cuttings and smaller bonsai such as Shohin & Mame.)

Small Kanuma 3-6mm – 17L Bag (for use in most sized pots and trees) Currently unavailable. See alternative below.

Medium Kanuma 6-12mm – 17L Bag ( for larger trees and pots)

Large Kanuma 12-21mm – 17L Bag (Used mainly for drainage layers in larger pots)

More Information:

In using Kanuma, We follow the repotting system recommended by all Japanese Bonsai Masters and Growers:
The first (bottom) layer is large (drainage) then 50/50 of medium and fine grade (depending on the size of your Bonsai) for the remainder of pot.

The Super Small grade of Kanuma can be used for cuttings and Mame sized trees and pots.

IMPORTANT NOTE:
Kanuma can be re-used several times, making it very economical (gently sieve them each time (removing dust) and water accordingly).

With Kanuma: After repotting, the pot should be watered copiously until the water runs out clear from the bottom of the pot. This ensures very little residue will form in the bottom of the bonsai pot.

SOIL MIXES:
In Japan, it rains for the month of June (Northern hemisphere) and the temperature is about 30°C; July 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.
We recommend you experiment with different mixes to ensure the best growing medium for your growing conditions/environment.
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KANUMA (acid pH):
Used principally for acid-loving bonsai - Azaleas/Rhododendrons, Camellias, etc, Satsuki in particular.
Satsuki/Azaleas: 100% with a little charcoal (In a dry summer climate such as South or Western Australia 5 - 10% Sphagnum Moss may be added.)
Orchids: Kanuma 6 parts, Matured pine fines (leaf mould) 2 parts, Coarse River Sand 2 parts.
Indoor Plants: Kanuma 3 parts, Akadama 4 parts, Matured pine fines 3 parts.
Bulbs: Kanuma 5 parts, Akadama 2 parts, Matured pine fines 3 parts.

NOTES:
Sphagnum Moss should be prepared by drying and then rubbing through a medium sieve to make even particles before adding to the mix.
When repotting do not jab too hard with the chopstick as this will break the granules down. Once the potting medium has been lightly jabbed with chopsticks, tap all sides of the pot to encourage further settling of the potting medium.
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.