What is it?
Japanese Kanuma comes from Kanuma City in Tochigi, Japan and is the result of a volcanic eruption by Mount Akagi around 45,000 years ago.
Why use it?
Kanuma is a very porous, soft particle which easily absorbs and retains moisture. Kanuma has a pH value of between 4.5 - 5.5.
The acidic nature of the Kanuma makes it ideal for all acid loving species such as camellias, rhododendrons, gardenia and more. It is also a popular component in carnivorous plant mixes for plants such as Nepenthes and can be mixed with long fibre moss or crushed lava stone.
As it is soft, fibrous roots such as those from the Azalea for example can penetrate the particle. This means smaller containers can be used as the tree can better utilize the full volume of the container.
How to use?
Do not mix Kanuma with organic material.
You can however mix some suitably sized (SMALL) akadama to the Kanuma, in a quantity of up to 20% of the mix which will help to hold the soil structure for longer.
As Kanuma is very soft and can create dust easily it is best to handle the product as little as possible. When seating a tree onto a layer of Kanuma, do not force or "jiggle" the tree back and forth over the Kanuma as this could crush some of the particles.
When using an implement to work Kanuma into the root ball, do so very gently so as to avoid breaking particles.
If you are used to watering very water retentive mixes containing organics then some adjustment to your routine might be required. Generally though, watering daily is all that will be required unless your climate is particularly dry and your plant is perspiring a lot.