# Chlorosis

> Yellowing of normally green plant tissue caused by too little chlorophyll, from nutrient shortage, poor root uptake, pH lockout, light damage, pests or normal ageing.

- Canonical: https://genetixbay.com/knowledge/glossary/chlorosis.html
- Also written: chlorotic, leaf chlorosis, yellowing of leaves
- Glossary category: Plant biology · 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"

Chlorosis is yellowing of tissue that should be green, because the leaf is making or keeping too little chlorophyll. It is a symptom, not a diagnosis: nitrogen, magnesium, iron, manganese, sulfur and zinc shortages all cause it, and so do [waterlogged](https://genetixbay.com/knowledge/glossary/overwatering.md) or [rotting roots](https://genetixbay.com/knowledge/glossary/root-rot.md), [pH](https://genetixbay.com/knowledge/glossary/ph.md) out of range, cold [root zones](https://genetixbay.com/knowledge/glossary/root-zone.md) and excess light (Marschner 2012).

## In practice

Where the chlorosis starts is the first clue. On old, lower leaves it usually means a [mobile nutrient](https://genetixbay.com/knowledge/glossary/mobile-nutrient.md) (N, Mg, K) is being moved out to feed new growth; on new growth it points to an immobile one (Fe, Mn, Zn, S, Ca, B) or to high root-zone pH (Cockson et al. 2019). Uniform chlorosis of the whole leaf, veins included, differs from [interveinal chlorosis](https://genetixbay.com/knowledge/glossary/interveinal-chlorosis.md), where the veins stay green. Chlorotic tissue can green up again if the cause is fixed early; once it turns brown it will not.

## Don't confuse with

- **Necrosis**: dead, brown or black tissue, which follows severe chlorosis.
- **Senescence**: normal ageing and [fade](https://genetixbay.com/knowledge/glossary/senescence.md) of old leaves, especially in late flower.
- **Light bleaching**: white or pale tops nearest the lamp, caused by light and heat rather than nutrition.

## Related terms

[Interveinal chlorosis](https://genetixbay.com/knowledge/glossary/interveinal-chlorosis.md), [Necrosis](https://genetixbay.com/knowledge/glossary/necrosis.md), [Chlorophyll](https://genetixbay.com/knowledge/glossary/chlorophyll.md), [Senescence](https://genetixbay.com/knowledge/glossary/senescence.md), [Mobile nutrient](https://genetixbay.com/knowledge/glossary/mobile-nutrient.md), [Immobile nutrient](https://genetixbay.com/knowledge/glossary/immobile-nutrient.md)

## Read more

- [Yellowing lower leaves on cannabis: a differential](https://genetixbay.com/knowledge/diagnosis/yellowing-lower-leaves.md)
- [Yellow new growth on cannabis: a differential](https://genetixbay.com/knowledge/diagnosis/yellow-new-growth.md)
- [Cannabis lookalike problems: how to tell them apart](https://genetixbay.com/knowledge/diagnosis/lookalikes.md)

## Sources

1. Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9
2. Cockson P, et al., 2019. Characterization of Nutrient Disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432