Cannabis harvest time has three main signs: trichome color, pistil color, and flower week count. Check plants each day in the final two weeks.
Sign 1: Trichome color
Use a 30x to 60x loupe or a USB microscope. Look at trichomes on the calyxes, not the sugar leaves. Sugar leaves turn amber first.
- Clear: immature. THC and CBD levels are low.
- Cloudy or milky: peak cannabinoid content.
- Amber: THC degrades to CBN. CBD hemp loses potency.
For high THC, harvest when most trichomes are cloudy and 5% to 10% are amber. For CBD hemp, harvest when trichomes are cloudy and amber is under 20%.
Sign 2: Pistil color and curl
Pistils are the hair-like strands on the flower. They start white. They turn orange, red, or brown. They curl inward toward the calyx. When 70% to 90% of pistils have darkened and curled, the plant is near harvest.
Sign 3: Flower week count
Count weeks from the first day of 12/12 light for photoperiod plants. Autoflowers count from sprout.
- Indica-dominant: 7 to 9 weeks.
- Sativa-dominant: 9 to 12 weeks.
- Autoflower: 8 to 10 weeks.
Week count is a guide. Trichomes and pistils override the calendar.
Tools and method
- Sample buds from the middle of the plant. Top colas mature first.
- Check in daylight or with a white LED. Colored lights change trichome color.
- Record trichome color each day for 5 days. Watch the trend.
Common errors
- Harvesting on a fixed date.
- Checking sugar leaves instead of calyxes.
- Using a phone zoom. It does not show trichome heads.
- Waiting for all pistils to turn brown. Some stay white.
Harvest timing changes cannabinoid and terpene profiles. A 3-day delay can shift THC to CBN. For CBD hemp, a late harvest lowers CBD and raises CBN.