---
title: Akadama in a terrarium | Glass Jar Garden
description: Akadama: Firm, rust-coloured clay granules from bonsai growing. Holds water and drains well. In the jar it has holds water 37.5 % by volume, pore space 65 %...
url: https://glassjar.garden/guide/soils/akadama/
---

Soils and layers

# Akadama

Firm, rust-coloured clay granules from bonsai growing. Holds water and drains well.

## What the simulation uses

- Holds water: 37.5 % by volume (Water it keeps after draining; the rest runs down to the drainage.)

- Pore space: 65 % by volume (Room for air and water between grains; low means roots suffocate when wet.)

- Weight: 675 g/L (How heavy a litre is.)

- pH: 6.5 to 7 pH (How acid it keeps the soil.)

- Mould risk: none (How much fresh food it gives white mould; high-risk soils fuzz over in the first weeks.)

- Breaks down in: 2 to 5 years (How long it lasts before rotting down to fine soil.)

- Nutrients: low (Plant food it brings.)

- Presses down to: 72 % of its loose depth (How far pressing can pack it, keeping its weight.)

## Description
This Japanese volcanic clay soaks up water and nutrients while still draining freely. The granules darken when wet, so you can judge moisture at a glance. After two to five years they crumble into fine mud that can clog drainage.

Also called bonsai soil, Japanese red clay.

Estimated, where sources were thin: bulk density, porosity, CEC estimated.

## Sources

- [en.wikipedia.org/wiki/Akadama](https://en.wikipedia.org/wiki/Akadama)
- [en.wikipedia.org/wiki/Clay](https://en.wikipedia.org/wiki/Clay)

[Grow it in a jar](https://glassjar.garden/?guide=soils/akadama)

[Activated charcoal](https://glassjar.garden/guide/soils/activated-charcoal/) · [Aquarium gravel](https://glassjar.garden/guide/soils/aquarium-gravel/) · [All soils and layers](https://glassjar.garden/guide/soils/)