---
title: Substrate barrier mesh in a terrarium | Glass Jar Garden
description: Substrate barrier mesh: Fine mesh that keeps soil out of the drainage. In the jar it has holds water 1 % by volume, pore space 60 % by volume, ph 6.5 to 7.5...
url: https://glassjar.garden/guide/soils/mesh-barrier/
---

Soils and layers

# Substrate barrier mesh
Reusable

Fine mesh that keeps soil out of the drainage.

## What the simulation uses

- Holds water: 1 % by volume (Water it keeps after draining; the rest runs down to the drainage.)

- Pore space: 60 % by volume (Room for air and water between grains; low means roots suffocate when wet.)

- 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: none (Plant food it brings.)

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

## Description
Skip it and fine particles clog the drainage, water wicks back up and the soil goes stale and airless. It is inert, takes up no depth and can be reused.

Also called fibreglass window screen, weed barrier, substrate divider.

Estimated, where sources were thin: bulk_density not meaningful (sheet material; ~100-150 g/m2 areal mass, est); porosity/water fields set to mesh-open-area estimates.

## Sources

- [joshsfrogs.com/sp/josh-s-frogs-substrate-barrier-24x18-inch-jf00652](https://joshsfrogs.com/sp/josh-s-frogs-substrate-barrier-24x18-inch-jf00652)
- [joshsfrogs.com/sp/mother-earthr-hydrotonr-original-10-liter-hydrtn10qt](https://joshsfrogs.com/sp/mother-earthr-hydrotonr-original-10-liter-hydrtn10qt)

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

[Sphagnum peat moss](https://glassjar.garden/guide/soils/peat-moss/) · [Topsoil](https://glassjar.garden/guide/soils/topsoil/) · [All soils and layers](https://glassjar.garden/guide/soils/)