Pistils are the female reproductive organs of cannabis flowers. The white or coloured 'hairs' growers call pistils are strictly the stigmas: each female flower has two, sticking out of its bract to catch pollen. They appear first at the nodes as preflowers, then by the hundred in buds, and darken through orange or brown with age, heat or pollination. Judge harvest by trichomes, not pistil colour.

What are pistils?

Short answer

A pistil is the female part of a flower: ovary, style and stigmas. On cannabis, the white or coloured "hairs" growers call pistils are the stigmas, two per flower, reaching out of the bract to catch pollen. They darken with age. Established botany.

Why

Each female flower is simple. One ovary sits inside a small leafy bract (the "calyx" to growers), topped by two long stigmas ^[2]. A pollinated flower makes a single seed.

Pistils show sex first. Single flowers form at the nodes once the plant matures; in one cultivar the first pair appeared at the 7th node, whatever the day length ^[3]. Paired white hairs at a node mean female.

Clusters of pistils mark real flowering. On photoperiod plants, at least three pairs of pistils at the top of the main shoot is the research definition of flowering onset, usually 8–14 days after short days begin ^[1].

The resin isn't on the hairs. Glandular trichomes, densest on the bracts, make the cannabinoids and terpenes ^[4]. That's why trichome maturity, not stigma colour, is the better harvest clock.

The numbers

Stage	What pistils look like
Preflower (~4–6 weeks from seed)	One pair of white hairs at a node
Onset of flower (~10–14 days after flip)	3+ pairs clustered at the top
Mid flower	Masses of fresh white stigmas
Late flower	Most curled, orange, red or brown
Pollinated flower	Withers and browns within days

What to do

Use paired white hairs at the nodes to identify females.
Log the day pistils cluster at the top as day 1 of flower.
Treat sudden, early browning as a stress clue: check heat and RH.
Decide harvest with a 60x loupe on the trichome heads.

Common mistakes

Harvesting by pistil colour alone.
Calling the bract and stigmas "the pistil" and expecting resin there.
Confusing stipules at the nodes with preflowers.

Full article: Cannabis plant biology
Answers: pistils browning early · checking trichomes · when plants show sex
Article: Trichome ripeness
Terms: pistil · stigma · bract

The female reproductive organ of a flower (ovary, style and stigmas); in cannabis growers loosely call the visible white stigmas "pistils".The sticky, hair-like tip of the female pistil that catches pollen; each cannabis female flower has two, white when fresh and darkening with age.In cannabis, the small leaf-like sheath (perigonal bract) that wraps each female flower's ovary and carries the densest capitate-stalked trichomes.A female flower with a pistil but no functional stamens; in cannabis, a bract-wrapped ovary topped by two stigmas.Botanically, the sepals of a flower; in female cannabis a thin, reduced perianth on the ovary, though growers use the word for the resinous bract.Pollination is the transfer of pollen onto a female flower's stigmas; in cannabis it is usually by wind, or by hand when breeders pollinate chosen branches to make seed.The daily length of light versus dark; photoperiod cannabis flowers when nights grow long enough, rather than at a fixed age.A hair-like outgrowth of the plant's skin; in cannabis the glandular types make and store the resin holding cannabinoids and terpenes.A cannabinoid is any compound that binds the body's cannabinoid receptors or shares the typical cannabis terpenophenolic structure; the plant-made ones are phytocannabinoids such as THCA and CBDA.Terpenes are volatile hydrocarbon compounds built from five-carbon isoprene units; in cannabis they are made in the trichome heads and are a major part of aroma and flavour.The first individual flowers that form at stem nodes during late vegetative growth, letting a grower tell male from female before full flowering.Relative humidity is the water vapour in air as a percentage of what it could hold at that temperature, so the same RH dries plants differently at different temperatures.A small handheld magnifier, typically 30-60x for cannabis use, used to inspect trichome heads and spot pests and male flowers.Trichome heads are the bulbous resin-filled tops of capitate glandular trichomes, where cannabis makes and stores nearly all its cannabinoids and terpenes; they are the raw material of hash.

Follow-up questions

When do pistils first appear?

Pistils first appear as single preflowers at the nodes once a cannabis plant matures, usually about 4–6 weeks from seed under long days, and around the 7th node in one study. On a photoperiod plant, clusters of pistils at the top of the main shoot appear about 10–14 days after the switch to 12/12, marking the real start of flower.

Why are my pistils turning brown?

Cannabis pistils turn brown or orange as the flowers age, which is normal in the last weeks of flower. They also darken early from heat, low humidity, handling, sprays or pollination, which withers the stigmas of fertilised flowers within days. Browning on its own is a weak harvest guide; check trichome heads with a 60x loupe instead.

Should I harvest when 70% of pistils are brown?

'Harvest when 70–90% of pistils are brown' is a rough rule, not a reliable one, because pistil colour also changes with heat, handling, humidity and cultivar. GenetixBay judges harvest by trichome heads: a few clear, mostly cloudy and some amber is a good mix, with the exact balance a matter of preference.

Sources

Spitzer-Rimon B, Duchin S, Bernstein N, Kamenetsky R. 2019. Architecture and florogenesis in female Cannabis sativa plants. Frontiers in Plant Science 10:350. doi.org/10.3389/fpls.2019.00350

Small E. 2015. Evolution and classification of Cannabis sativa (marijuana, hemp) in relation to human utilization. Botanical Review 81:189-294. doi.org/10.1007/s12229-015-9157-3

Spitzer-Rimon B, Shafran-Tomer H, Gottlieb GH, et al. 2022. Non-photoperiodic transition of female cannabis seedlings from juvenile to adult reproductive stage. Plant Reproduction 35(4):265-277. doi.org/10.1007/s00497-022-00449-0

Livingston SJ, Quilichini TD, Booth JK, et al. 2020. Cannabis glandular trichomes alter morphology and metabolite content during flower maturation. The Plant Journal 101(1):37-56. doi.org/10.1111/tpj.14516