---
title: Damping-off in a terrarium | Glass Jar Garden
description: Damping-off / root rot water mould (Pythium spp.): A water mould in soggy soil that rots roots and seedlings.
url: https://glassjar.garden/guide/moulds/pythium-damping-off/
---

Moulds and films

# Damping-off / root rot water mould
Pythium spp.

A water mould in soggy soil that rots roots and seedlings.

## Care

- Air humidity: 90 to 100%

- Temperature: 10 to 30 °C

## Description
Technically a water mould rather than a true fungus, it swims through waterlogged soil. You rarely see fuzz, just seedlings toppling in patches and brown, mushy roots. A drainage layer, lighter watering and sterilised soil are the best defence.

Also called damping off, root rot, water mould.

Estimated, where sources were thin: spread_cm_per_day in soil (2-4 day figure is hydroponic); temp_c; humidity_rh_pct.

## Sources

- [en.wikipedia.org/wiki/Pythium](https://en.wikipedia.org/wiki/Pythium)
- [en.wikipedia.org/wiki/Damping_off](https://en.wikipedia.org/wiki/Damping_off)

[Grow it in a jar](https://glassjar.garden/?guide=moulds/pythium-damping-off)

[Blue-green mould](https://glassjar.garden/guide/moulds/penicillium-blue-green-mould/) · [Green mould](https://glassjar.garden/guide/moulds/trichoderma-green-mould/) · [All moulds and films](https://glassjar.garden/guide/moulds/)