# Organic fertiliser

> An organic fertiliser supplies nutrients from plant, animal or mineral-rock sources that soil microbes must break down into ions before roots can absorb them.

- Canonical: https://genetixbay.com/knowledge/glossary/organic-fertiliser.html
- Also written: organic fertilizer, organic nutrients, organic nutes, organic amendments, natural fertiliser
- 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"

An organic fertiliser is a nutrient source derived from living or once-living material, such as manures, composts, meals (blood, bone, fish, feather, kelp, seed), or from minimally processed mined minerals. Most of its nutrients are held in organic compounds that microbes mineralise into the same ions found in mineral feeds, so release depends on temperature, moisture and microbial activity.

## In practice

Organic feeding suits soil and living-soil systems, where microbial life does the conversion. Release is slower and harder to measure, so [EC](https://genetixbay.com/knowledge/glossary/ec.md) readings mean little. Caplan, Dixon and Zheng found cannabis in [coir](https://genetixbay.com/knowledge/glossary/coco-coir.md) responded well to a liquid organic fertiliser at the right rate; Massuela and colleagues compared organic and [mineral fertiliser](https://genetixbay.com/knowledge/glossary/mineral-fertiliser.md) levels in flowering cannabis. In [recirculating hydro](https://genetixbay.com/knowledge/glossary/recirculating-system.md), raw organics tend to clog lines and feed biofilm. Certification rules for "organic" differ by jurisdiction.

## Don't confuse with

- **Mineral (synthetic) fertiliser**: soluble salts delivering ions directly.
- **Living soil**: a whole system, not a single product.

## Myth check

Plants mostly don't care where the ions come from (GenetixBay house position). Organic feeding may bring slight [flavonoid](https://genetixbay.com/knowledge/glossary/flavonoid.md) or [terpene](https://genetixbay.com/knowledge/glossary/terpene.md) differences, but that is unproven. See [organic vs mineral](https://genetixbay.com/knowledge/nutrients/organic-vs-mineral.md).

## Related terms

[Mineral fertiliser](https://genetixbay.com/knowledge/glossary/mineral-fertiliser.md), [Molasses](https://genetixbay.com/knowledge/glossary/molasses.md), [Humic acid](https://genetixbay.com/knowledge/glossary/humic-acid.md), [Biostimulant](https://genetixbay.com/knowledge/glossary/biostimulant.md), [N-P-K ratio](https://genetixbay.com/knowledge/glossary/npk-ratio.md)

## Read more

- [Organic vs mineral nutrition for cannabis: what the trials show](https://genetixbay.com/knowledge/nutrients/organic-vs-mineral.md)
- [Living soil (no-till, water-only organic growing)](https://genetixbay.com/knowledge/systems/living-soil.md)

## Sources

1. Caplan D, Dixon M, Zheng Y. 2017. Optimal rate of organic fertilizer during the flowering stage for cannabis grown in two coir-based substrates. HortScience 52(12):1796-1803. https://doi.org/10.21273/HORTSCI12401-17
2. Massuela DC, Munz S, Hartung J, Nkebiwe PM, Graeff-Honninger S. 2023. Cannabis Hunger Games: nutrient stress induction in flowering stage - impact of organic and mineral fertilizer levels on biomass, cannabidiol (CBD) yield and nutrient use efficiency. Frontiers in Plant Science 14:1233232. https://doi.org/10.3389/fpls.2023.1233232