Soil mixes: drainage first, everything else second

Every workable bonsai mix solves the same problem first: water has to pass through and air has to follow it in, or roots drown in a container far shallower than open ground. Akadama, the fired clay most mixes start from, holds water and nutrients while breaking down slowly over a few years, which is exactly why it gets replaced at repotting rather than topped up. Kanuma, more acid and more open, suits azaleas and other acid-loving species. Kiryu, hard and sandy, adds drainage for pines and other conifers that resent wet feet. The right blend is a question of species and climate more than any single fixed recipe — start from what the species' care plan calls for, not a universal ratio.