# EDTA

> EDTA (ethylenediaminetetraacetic acid) is the most common synthetic chelating agent in fertilisers, effective for iron up to about pH 6.0-6.5.

- Canonical: https://genetixbay.com/knowledge/glossary/edta.html
- Also written: ethylenediaminetetraacetic acid, EDTA chelate, Na2EDTA, edetate
- Glossary category: Nutrients · 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"

EDTA, ethylenediaminetetraacetic acid, is a synthetic [chelating agent](https://genetixbay.com/knowledge/glossary/chelate.md) that binds metal ions at six points. In fertilisers it carries iron ([Fe-EDTA](https://genetixbay.com/knowledge/glossary/iron-chelate.md), about 13% Fe), and often zinc, [manganese](https://genetixbay.com/knowledge/glossary/manganese.md) and copper. It is cheap and widely used.

## In practice

Fe-EDTA works well in hydro and [soilless](https://genetixbay.com/knowledge/glossary/soilless.md) media kept around [pH](https://genetixbay.com/knowledge/glossary/ph.md) 5.5-6.2. Above about 6.5 its iron becomes progressively less available, so it is a weak choice for alkaline water, high-pH soil or [coco](https://genetixbay.com/knowledge/glossary/coco-coir.md) run high. Fe-EDTA also breaks down under strong light, so clear reservoirs and lines exposed to light lose iron faster. At high pH, EDTA can also pick up calcium, displacing the iron it carries. EDTA is not readily biodegradable, which has raised environmental questions about its heavy use in agriculture.

## Don't confuse with

- **DTPA**: a related chelate, stable to a higher pH.
- **EDDHA**: much more stable at high pH, used for alkaline soils.
- **HEDTA**: a related chelate with intermediate properties.

## Related terms

[Chelate](https://genetixbay.com/knowledge/glossary/chelate.md), [Iron chelate](https://genetixbay.com/knowledge/glossary/iron-chelate.md), [DTPA](https://genetixbay.com/knowledge/glossary/dtpa.md), [EDDHA](https://genetixbay.com/knowledge/glossary/eddha.md), [Iron](https://genetixbay.com/knowledge/glossary/iron.md)

## Read more

- [Iron (Fe) in cannabis: yellow new growth, chelates and pH](https://genetixbay.com/knowledge/nutrients/iron.md)
- [Hydroponic salts explained: what each fertiliser salt supplies](https://genetixbay.com/knowledge/nutrients/hydroponic-salts.md)

## Sources

1. HortScience. 2025. Iron chelates (Fe-EDTA, Fe-DTPA, Fe-EDDHA) in high-pH soilless media. HortScience 60(3):404. https://journals.ashs.org/view/journals/hortsci/60/3/article-p404.xml
2. Sonneveld C, Voogt W. 2009. Plant Nutrition of Greenhouse Crops. Springer. https://doi.org/10.1007/978-90-481-2532-6