When to harvest cannabis - how to read trichomes and pick your window

Grow Support
1

Harvest timing does more to shape your final jar than almost anything else you do in flower, and it’s the one thing new growers most often rush. Here’s how to judge it properly.

What you’re actually looking at
Trichomes are the resin glands covering the buds and sugar leaves. The ones worth reading are the capitate-stalked ones - a stalk with a round head on top. That head changes colour as the plant finishes, and that colour is your clock.

The three stages

  1. Clear - glassy and transparent. The plant is still filling. Harvesting here gives you a thin, underwhelming result.
  2. Cloudy / milky - opaque white. This is peak ripeness for most growers and usually gives the most energizing, uplifting character.
  3. Amber - the head has gone brown-gold and is starting to degrade. Growers generally describe amber-heavy harvests as a heavier, more calming experience.

Most people aim for mostly cloudy with around 10–20% amber. Push further into amber if you prefer that heavier character, pull earlier if you don’t.

How to look

  • A 60x jeweller’s loupe is the cheap standard. A USB microscope is easier on the eyes. A modern phone macro lens will do at a push.
  • Check the calyxes on the buds, not the sugar leaves. Sugar leaves turn amber well before the flower does and will trick you into chopping early.
  • Look under natural or plain white light. Under HPS or a blurple LED you cannot judge colour at all.
  • Check several sites - top colas mature ahead of lower bud, so sample a few spots before deciding.

What not to rely on

  • Pistils. The old “wait until 70–90% have darkened” rule gets you in the right week, not the right day. Treat it as a prompt to start checking trichomes, nothing more.
  • The breeder’s week count. “8–10 weeks from seed” on an auto or “8–10 weeks” of flower on a photo is an estimate made in someone else’s room. Your environment shifts it.

A staggered harvest is allowed
There is no rule saying the whole plant comes down at once. Taking the tops when they’re ready and leaving lower bud another 7–10 days under the light is a legitimate way to get more out of a plant.

Common mistakes

  • Chopping early because the pistils looked done
  • Reading sugar leaf trichomes instead of the flower
  • Judging colour under the grow light
  • Checking one spot on one cola and calling it
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