---
title: Worm castings in a terrarium | Glass Jar Garden
description: Worm castings: Crumbly compost made by worms, rich in nutrients. In the jar it has holds water 52.5 % by volume, pore space 67.5 % by volume, weight 600 g/L.
url: https://glassjar.garden/guide/soils/worm-castings/
---

Soils and layers

# Worm castings

Crumbly compost made by worms, rich in nutrients.

## What the simulation uses

- Holds water: 52.5 % by volume (Water it keeps after draining; the rest runs down to the drainage.)

- Pore space: 67.5 % by volume (Room for air and water between grains; low means roots suffocate when wet.)

- Weight: 600 g/L (How heavy a litre is.)

- pH: 6.5 to 7.5 pH (How acid it keeps the soil.)

- Mould risk: high (How much fresh food it gives white mould; high-risk soils fuzz over in the first weeks.)

- Breaks down in: 1 to 3 years (How long it lasts before rotting down to fine soil.)

- Nutrients: high (Plant food it brings.)

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

## Description
Crumbly compost made by worms, rich in nutrients. A little mixed into soil feeds plants well, but it feeds white mould just as happily, so use it sparingly.

Also called vermicompost.

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

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

[Vermiculite](https://glassjar.garden/guide/soils/vermiculite/) · [Zeolite](https://glassjar.garden/guide/soils/zeolite/) · [All soils and layers](https://glassjar.garden/guide/soils/)