# Chelate

> A chelate is a metal ion held by an organic molecule at several points, keeping micronutrients such as iron, zinc and manganese dissolved and available across a wider pH range.

- Canonical: https://genetixbay.com/knowledge/glossary/chelate.html
- Also written: chelated, chelation, chelating agent, chelated micronutrients, chelates
- 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"

A chelate is a complex in which an organic molecule, the chelating agent, grips a metal ion at two or more points, like a claw (the word comes from the Greek for claw). The grip protects the metal from reacting with hydroxide, [phosphate](https://genetixbay.com/knowledge/glossary/phosphate.md) or carbonate and dropping out of solution. Iron, [manganese](https://genetixbay.com/knowledge/glossary/manganese.md), zinc and copper are the metals most often chelated in fertilisers.

## In practice

Without chelation, iron in particular precipitates within hours once [pH](https://genetixbay.com/knowledge/glossary/ph.md) rises above about 6. Synthetic chelates differ in stability: [EDTA](https://genetixbay.com/knowledge/glossary/edta.md) is fine for typical hydro pH, [DTPA](https://genetixbay.com/knowledge/glossary/dtpa.md) holds higher, and [EDDHA](https://genetixbay.com/knowledge/glossary/eddha.md) survives alkaline conditions. Natural compounds such as amino acids, humic and [fulvic acids](https://genetixbay.com/knowledge/glossary/fulvic-acid.md) and citrate also bind metals, but more loosely and less predictably. Labels list which elements are chelated and with what agent.

## Don't confuse with

- **Complexing agents**: a broader class; not all complexes are true chelates.
- **Biostimulant**: a marketing category; a chelate is a defined chemical form.
- **Sequestered**: often used loosely on labels to mean chelated or complexed.

## Myth check

"Chelated" on a label does not make a product better in itself. The chelate type has to match the root-zone pH. See [pH and nutrient availability](https://genetixbay.com/knowledge/ph-ec/ph-nutrient-availability.md).

## Related terms

[Iron chelate](https://genetixbay.com/knowledge/glossary/iron-chelate.md), [EDTA](https://genetixbay.com/knowledge/glossary/edta.md), [DTPA](https://genetixbay.com/knowledge/glossary/dtpa.md), [EDDHA](https://genetixbay.com/knowledge/glossary/eddha.md), [Amino acid chelate](https://genetixbay.com/knowledge/glossary/amino-acid-chelate.md), [Micronutrient](https://genetixbay.com/knowledge/glossary/micronutrient.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. Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9