# Chlorophyll

> The green pigment in chloroplasts that absorbs mainly blue and red light to drive photosynthesis; chlorophyll a and b are the main forms in plants.

- Canonical: https://genetixbay.com/knowledge/glossary/chlorophyll.html
- Also written: chlorophyll a, chlorophyll b, chlorophylls, green pigment
- 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"

Chlorophyll is the pigment that captures light for [photosynthesis](https://genetixbay.com/knowledge/glossary/photosynthesis.md). Plants carry chlorophyll a and b, which absorb strongly in the blue (around 430-450 nm) and red (around 640-680 nm) and reflect green. Each molecule has a magnesium atom at its centre, and building it needs nitrogen, magnesium and iron, among other things.

## In practice

Leaf colour is largely chlorophyll status:
- **Pale or yellow older leaves**: often nitrogen or magnesium moving to new growth, or natural late-flower [senescence](https://genetixbay.com/knowledge/glossary/senescence.md).
- **Pale new growth**: often iron, [sulfur](https://genetixbay.com/knowledge/glossary/sulfur.md) or root-zone/[pH](https://genetixbay.com/knowledge/glossary/ph.md) issues.
- **Dark, glossy green**: frequently excess nitrogen.

Chlorophyll breakdown in late flower reveals other pigments (carotenoids, anthocyanins) and is normal, especially with a [nitrogen taper](https://genetixbay.com/knowledge/glossary/nitrogen-taper.md).

After harvest, chlorophyll still in the material breaks down during a slow dry and cure. Material dried too fast keeps a green, grassy, [hay-like smell](https://genetixbay.com/knowledge/glossary/hay-smell.md). Drying and curing, not [flushing](https://genetixbay.com/knowledge/glossary/flushing.md), decide that.

## Don't confuse with

- **Anthocyanin**: purple/red pigment in the vacuole, not photosynthetic.
- **Carotenoids**: yellow-orange accessory pigments.
- **Chlorosis**: the symptom of losing chlorophyll.

## Myth check

"Flushing removes chlorophyll" is a Myth. Chlorophyll is broken down by the plant's own senescence and by a proper dry, not by plain water at the roots. See [the flush debate](https://genetixbay.com/knowledge/harvest-cure/flush-debate.md).

## Related terms

[Photosynthesis](https://genetixbay.com/knowledge/glossary/photosynthesis.md), [Anthocyanin](https://genetixbay.com/knowledge/glossary/anthocyanin.md), [Senescence](https://genetixbay.com/knowledge/glossary/senescence.md), [Hay smell](https://genetixbay.com/knowledge/glossary/hay-smell.md)

## Read more

- [Yellowing lower leaves on cannabis: a differential](https://genetixbay.com/knowledge/diagnosis/yellowing-lower-leaves.md)
- [Drying cannabis: the 60/60 method and water activity](https://genetixbay.com/knowledge/harvest-cure/drying.md)

## Sources

1. Taiz L, Zeiger E, Møller IM, Murphy A. 2015. Plant Physiology and Development, 6th edition. Sinauer Associates.
2. Alden MJ, Faust JE. 2025. Exploring the legacy practice of flushing in controlled-environment production of high-CBD cannabis. HortScience 60(10):1818-1825. https://doi.org/10.21273/HORTSCI18752-25