# Magnesium nitrate

> Magnesium nitrate supplies about 9.5% magnesium and 11% nitrogen as nitrate, and unlike Epsom salt it can share a concentrated stock with calcium nitrate.

- Canonical: https://genetixbay.com/knowledge/glossary/magnesium-nitrate.html
- Also written: Mg(NO3)2, magnesium nitrate hexahydrate, 11-0-0 magnesium, mag nitrate
- 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"

Magnesium nitrate is a soluble salt of magnesium and [nitrate](https://genetixbay.com/knowledge/glossary/nitrate.md), sold as the hexahydrate Mg(NO3)2·6H2O. It contains about 9.5% Mg and 10.9% N, all as nitrate. It carries no [sulfate](https://genetixbay.com/knowledge/glossary/sulfate.md), so it does not precipitate with calcium.

## In practice

It is used to add magnesium where sulfate is already high, or to build a one-part or [Cal-Mag](https://genetixbay.com/knowledge/glossary/cal-mag.md) concentrate where calcium and magnesium must share a bottle. It also adds nitrogen, so it is less suitable than [magnesium sulfate](https://genetixbay.com/knowledge/glossary/magnesium-sulfate.md) when tapering N in late flower. Liquid Cal-Mag supplements are often [calcium nitrate](https://genetixbay.com/knowledge/glossary/calcium-nitrate.md) plus magnesium nitrate.

## Units and formula

1 g/L gives about 95 mg/L (ppm) Mg and 109 mg/L N.

## Don't confuse with

- **Magnesium sulfate (Epsom salt)**: Mg with [sulfur](https://genetixbay.com/knowledge/glossary/sulfur.md), no nitrogen, must stay apart from concentrated calcium.
- **Calcium nitrate**: the calcium counterpart.
- **Cal-Mag**: a finished product that may contain magnesium nitrate.

## Related terms

[Magnesium](https://genetixbay.com/knowledge/glossary/magnesium.md), [Nitrate](https://genetixbay.com/knowledge/glossary/nitrate.md), [Magnesium sulfate](https://genetixbay.com/knowledge/glossary/magnesium-sulfate.md), [Cal-Mag](https://genetixbay.com/knowledge/glossary/cal-mag.md), [A/B nutrient](https://genetixbay.com/knowledge/glossary/a-b-nutrient.md)

## Read more

- [Hydroponic salts explained: what each fertiliser salt supplies](https://genetixbay.com/knowledge/nutrients/hydroponic-salts.md)
- [Magnesium (Mg) in cannabis: interveinal yellowing, targets and the K-Ca competition](https://genetixbay.com/knowledge/nutrients/magnesium.md)

## Sources

1. Sonneveld C, Voogt W. 2009. Plant Nutrition of Greenhouse Crops. Springer. https://doi.org/10.1007/978-90-481-2532-6