# Silica

> Silica is silicon dioxide (SiO2); growers use the word loosely for any silicon supplement added to stiffen stems and improve stress tolerance.

- Canonical: https://genetixbay.com/knowledge/glossary/silica.html
- Also written: SiO2, silicon dioxide, silica supplement, silica additive
- Glossary category: Nutrients · Evidence: Supported
- 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"

Silica is silicon dioxide, the compound in quartz sand and glass, and in the glassy deposits plants form in their tissues. In growing slang, "silica" means any [silicon](https://genetixbay.com/knowledge/glossary/silicon.md) supplement, most often [potassium silicate](https://genetixbay.com/knowledge/glossary/potassium-silicate.md), sometimes [stabilised](https://genetixbay.com/knowledge/glossary/stabilisation.md) silicic acid or silica-rich amendments such as diatomaceous earth, rice [hulls](https://genetixbay.com/knowledge/glossary/seed-coat.md) or basalt dust.

## In practice

Liquid silicate supplements go into plain water first, before other nutrients, then the [pH](https://genetixbay.com/knowledge/glossary/ph.md) is adjusted, because they are strongly alkaline and can gel or precipitate in a concentrated feed. Solid silica amendments release silicon slowly in soil. Cannabis does take up and deposit silicon, as Guerriero and colleagues showed, and growers report stiffer stems, though controlled cannabis yield data are limited.

## Don't confuse with

- **Silicon**: the element itself.
- **Silica gel**: a drying desiccant in packets, not a plant supplement.
- **Diatomaceous earth for pests**: used as a physical insecticide, though it also contains silica.

## Related terms

[Silicon](https://genetixbay.com/knowledge/glossary/silicon.md), [Potassium silicate](https://genetixbay.com/knowledge/glossary/potassium-silicate.md), [Beneficial element](https://genetixbay.com/knowledge/glossary/beneficial-element.md)

## Read more

- [Silicon (Si) for cannabis: beneficial, not essential, and how to dose it](https://genetixbay.com/knowledge/nutrients/silicon.md)

## Sources

1. Guerriero G, Deshmukh R, Sonah H, Sergeant K, Hausman JF, Lentzen E, Valle N, Siddiqui KS, Exley C. 2019. Identification of the aquaporin gene family in Cannabis sativa and evidence for the accumulation of silicon in its tissues. Plant Science 287:110167. https://doi.org/10.1016/j.plantsci.2019.110167
2. Epstein E. 1994. The anomaly of silicon in plant biology. PNAS 91(1):11-17. https://doi.org/10.1073/pnas.91.1.11