Akadama

Akadama (赤玉土, akadamatsuchi, red ball earth) is a naturally occurring, granular clay-like mineral used as soil for bonsai trees and other container-grown plants.

Akadama may also act as one component of growing medium when combined with other elements such as sand, composted bark, peat, or crushed lava.

[1] While akadama is more costly than alternative soil components, it is prized by many growers for its ability to retain water and nutrients while still providing porosity and free drainage.

Still other growers claim that when subjected to cold and wet climates, the granules progressively break down into smaller particles that inhibit drainage, an unwanted characteristic of bonsai soil.

It can be used alone or mixed in as an amendment to other soil substrates such as lava rock, pumice, stone, peat moss, bark, etc.