# Coco coir

> Coco coir is a growing medium made from processed coconut husk, prized for holding water and air at once; it binds calcium and magnesium unless buffered.

- Canonical: https://genetixbay.com/knowledge/glossary/coco-coir.html
- Also written: coco, coir, coconut coir, coco peat, cocopeat, coco fibre, coco chips
- 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"

Coco coir is the fibrous material from coconut husks, processed into fine pith (coco peat), fibre and chips. It holds a lot of water while still leaving plenty of [air space](https://genetixbay.com/knowledge/glossary/air-filled-porosity.md), rewets easily, resists compaction and breaks down slowly. It carries a natural [cation exchange capacity](https://genetixbay.com/knowledge/glossary/cation-exchange-capacity.md), holding potassium and [sodium](https://genetixbay.com/knowledge/glossary/sodium.md) from processing.

## In practice

Raw coco can carry salts from washing in brackish water; quality products are washed to low [EC](https://genetixbay.com/knowledge/glossary/ec.md). Its exchange sites also tend to take up calcium and magnesium and release potassium and sodium, which is why coco is pre-treated ("buffered") with a calcium solution and why coco feeds carry more calcium and magnesium. Run it like hydro: feed with every watering at about pH 5.8-6.2, water to [10-20% runoff](https://genetixbay.com/knowledge/glossary/watering-to-runoff.md), and never let it dry completely. Coco rewards frequent [fertigation](https://genetixbay.com/knowledge/glossary/fertigation.md); small pots fed several times a day perform strongly.

## Don't confuse with

- **Peat**: also a fine organic medium, but more acidic and harder to rewet.
- **Coco (food)**: coconut flesh and water; unrelated.

## Myth check

[Cal-Mag](https://genetixbay.com/knowledge/glossary/cal-mag.md) needs in coco come from its cation exchange, [RO water](https://genetixbay.com/knowledge/glossary/ro-water.md) and cultivar, not from LED lighting (GenetixBay: Myth). See [buffering coco](https://genetixbay.com/knowledge/ph-ec/buffering-coco.md).

## Related terms

[Buffering capacity](https://genetixbay.com/knowledge/glossary/buffering-capacity.md), [Cation exchange capacity](https://genetixbay.com/knowledge/glossary/cation-exchange-capacity.md), [Drain-to-waste](https://genetixbay.com/knowledge/glossary/drain-to-waste.md), [High-frequency fertigation](https://genetixbay.com/knowledge/glossary/high-frequency-fertigation.md), [Perlite](https://genetixbay.com/knowledge/glossary/perlite.md)

## Read more

- [Growing in coco coir](https://genetixbay.com/knowledge/systems/coco.md)
- [Buffering coco coir: why it matters and how to do it](https://genetixbay.com/knowledge/ph-ec/buffering-coco.md)

## Sources

1. Abad M, Noguera P, Puchades R, Maquieira A, Noguera V, 2002. Physico-chemical and chemical properties of some coconut coir dusts for use as a peat substitute for containerised ornamental plants. Bioresource Technology 82(3):241–245. https://doi.org/10.1016/S0960-8524(01)00189-4
2. 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
3. Caplan D, Dixon M, Zheng Y, 2017. Optimal rate of organic fertilizer during the vegetative-stage for cannabis grown in two coir-based substrates. HortScience 52(9):1307–1312. https://doi.org/10.21273/HORTSCI12401-17