---
title: Decomposed granite in a terrarium | Glass Jar Garden
description: Decomposed granite: Gritty crushed granite that drains fast, made for arid builds. In the jar it has holds water 11.5 % by volume, pore space 35 % by volume,...
url: https://glassjar.garden/guide/soils/decomposed-granite/
---

Soils and layers

# Decomposed granite

Gritty crushed granite that drains fast, made for arid builds.

## What the simulation uses

- Holds water: 11.5 % by volume (Water it keeps after draining; the rest runs down to the drainage.)

- Pore space: 35 % by volume (Room for air and water between grains; low means roots suffocate when wet.)

- Weight: 1650 g/L (How heavy a litre is.)

- pH: 6.5 to 7.5 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.)

- Nutrients: low (Plant food it brings.)

- Presses down to: 97 % of its loose depth (How far pressing can pack it, keeping its weight.)

## Description
Gritty crushed granite that drains fast, made for arid builds. It is heavy and holds little water. Use it under the soil or as a dry top layer.

Also called DG, granite grit.

Estimated, where sources were thin: values estimated from hobby and horticultural references; not measured.

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

[Cork crumbs](https://glassjar.garden/guide/soils/cork-bits/) · [Dried long-fibre sphagnum moss](https://glassjar.garden/guide/soils/sphagnum-dried/) · [All soils and layers](https://glassjar.garden/guide/soils/)