So that our bonsai have a healthy root system, that is, properly aerated, capable of absorbing water without later having problems as a consequence of a low or high pH, it is very important to know the needs of the species we are cultivating since for example an olive tree will not require the same substrate as a Japanese maple. While we could simply put black peat with a little perlite on the first one, the second one will do much better to mix it with one called kanuma.
What is kanuma? This word may sound very strange to you, in fact, it is so unknown that only those who have been working with bonsai for a while know about it. But it is one of the most recommended substrates for acidophilic trees and shrubs. So if you have any plants that don't like lime, grow them in kanuma.
What is kanuma?
In this granulated substrate that comes from volcanic debris from the Kanuma area, in Japan. It is very similar to akadama, but with two important differences: it is much lighter and has an acid pH, around 6, which is why it is used especially in acidophilic plants.
It has a high water holding capacity, and, at the same time, allows water to drain quickly, avoiding that the roots are flooded. It is inert, that is, it has no nutrient whatsoever, so the bonsai must be fertilized regularly so that it can grow with strength and vigor.
How is it used: alone or mixed?
Generally, it is used alone. The substrate in bonsai really only has one function: to serve as an anchor to the plant that is being cultivated. As kanuma is acidic, it is very interesting to use it so that the roots of our beloved acidophilic plants (azaleas, camellias, gardenias, maples, etc.) can grow and develop without problems.
But if you want to mix, we recommend mixing it with 30% kiryuzuna, since it is also granulated and also has a very good capacity to hold fertilizer due to the cationic exchange that it produces with it due to its chemical composition.
I hope that now you can have much more beautiful bonsai with the kanuma 🙂.