# Biostimulant

> A biostimulant is a product claimed to improve plant growth, uptake or stress tolerance by means other than supplying nutrients, such as seaweed extract, humics, amino acids or microbes.

- Canonical: https://genetixbay.com/knowledge/glossary/biostimulant.html
- Also written: biostimulants, bio-stimulant, plant biostimulant, growth enhancer
- Glossary category: Nutrients · Evidence: Contested
- 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"

A biostimulant is a substance or microorganism applied to plants or the [root zone](https://genetixbay.com/knowledge/glossary/root-zone.md) to improve nutrient uptake, efficiency, stress tolerance or quality, independently of its own nutrient content. Common categories are humic and [fulvic](https://genetixbay.com/knowledge/glossary/fulvic-acid.md) substances, seaweed and plant extracts, protein hydrolysates and amino acids, chitosan, and beneficial bacteria and fungi. Regulatory definitions differ by jurisdiction.

## In practice

Some categories have reasonable evidence in some crops, such as [mycorrhizae](https://genetixbay.com/knowledge/glossary/mycorrhizae.md) in low-phosphorus soils and certain seaweed extracts under stress. In cannabis, controlled data are sparse, and effects found so far are small or inconsistent (Evidence: Contested). Results depend heavily on product, dose, medium and cultivar. Growers who want to know should run a side-by-side with an untreated control of the same cultivar.

## Don't confuse with

- **Fertiliser**: supplies nutrients by definition.
- **Plant growth regulator**: hormone-like substances that directly alter growth, regulated differently.

## Myth check

Label claims for biostimulants often run ahead of the evidence. See [buyer beware: label claims](https://genetixbay.com/knowledge/basics/buyer-beware-label-claims.md) and [Mythbusters](https://genetixbay.com/knowledge/mythbusters.md).

## Related terms

[Humic acid](https://genetixbay.com/knowledge/glossary/humic-acid.md), [Fulvic acid](https://genetixbay.com/knowledge/glossary/fulvic-acid.md), [Amino acid chelate](https://genetixbay.com/knowledge/glossary/amino-acid-chelate.md), [Molasses](https://genetixbay.com/knowledge/glossary/molasses.md), [Organic fertiliser](https://genetixbay.com/knowledge/glossary/organic-fertiliser.md)

## Read more

- [Buyer beware: potency labels, strain names and other claims that don't hold up](https://genetixbay.com/knowledge/basics/buyer-beware-label-claims.md)
- [Organic vs mineral nutrition for cannabis: what the trials show](https://genetixbay.com/knowledge/nutrients/organic-vs-mineral.md)

## Sources

1. Bernstein N, Gorelick J, Zerahia R, Koch S. 2019. Impact of N, P, K, and humic acid supplementation on the chemical profile of medical cannabis (Cannabis sativa L). Frontiers in Plant Science 10:736. https://doi.org/10.3389/fpls.2019.00736