# Peat

> Peat is partially decomposed sphagnum moss from bogs, the base of most potting mixes; it holds water and nutrients well but is acidic and needs lime.

- Canonical: https://genetixbay.com/knowledge/glossary/peat.html
- Also written: peat moss, sphagnum peat, sphagnum peat moss, peat-based mix, peat-lite
- Glossary category: Systems and media · Evidence: Established
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

Peat (sphagnum peat moss) is the slowly decomposed remains of bog mosses, harvested from peatlands. It is light, very water-retentive, has a useful [cation exchange capacity](https://genetixbay.com/knowledge/glossary/cation-exchange-capacity.md) and is naturally acidic (raw [pH](https://genetixbay.com/knowledge/glossary/ph.md) about 3.5-4.5). Mixed with lime to raise the pH, plus [perlite](https://genetixbay.com/knowledge/glossary/perlite.md) and fertiliser, it forms the base of most commercial [potting mixes](https://genetixbay.com/knowledge/glossary/potting-mix.md), including many sold as "soil".

## In practice

Peat mixes work well for cannabis at a pH of about 6.0-6.5 in the [root zone](https://genetixbay.com/knowledge/glossary/root-zone.md). When very dry, peat becomes hydrophobic and sheds water; rewet it slowly or with a wetting agent, and avoid [letting it dry out](https://genetixbay.com/knowledge/glossary/wet-dry-cycle.md) fully. Mixes typically lose their starter fertiliser after two to four weeks.

Peat extraction releases stored carbon and destroys bog habitat; [coco](https://genetixbay.com/knowledge/glossary/coco-coir.md) and composted bark are common alternatives where growers want to reduce peat use.

## Don't confuse with

- **Coco peat**: coconut pith, sometimes called peat but a different material.
- **Peat pellets**: compressed peat discs for seeds and clones.

## Related terms

[Potting mix](https://genetixbay.com/knowledge/glossary/potting-mix.md), [Coco coir](https://genetixbay.com/knowledge/glossary/coco-coir.md), [Perlite](https://genetixbay.com/knowledge/glossary/perlite.md), [Cation exchange capacity](https://genetixbay.com/knowledge/glossary/cation-exchange-capacity.md), [Soilless](https://genetixbay.com/knowledge/glossary/soilless.md)

## Read more

- [Growing in soil (potting mix with bottled feed)](https://genetixbay.com/knowledge/systems/soil.md)

## Sources

1. Raviv M, Lieth JH, Bar-Tal A (eds), 2019. Soilless Culture: Theory and Practice, 2nd ed. Elsevier. https://doi.org/10.1016/C2015-0-01807-5