Harvest Time Calculator
Calculate your ideal harvest date — early, optimal or late, depending on the effect you’re after.
Why harvest timing makes all the difference
Trichomes as your guide
Trichomes are the tiny resin glands on the buds — under a loupe you can see three stages: clear (immature), cloudy (milky; peak potency) and amber (THC breaking down into CBN, more sedating). The mix determines your harvest style.
Breeder info as a starting point
The flowering times printed on seed packs are guidelines under ideal conditions. Temperature, light, stress and genetic variation can shift the real harvest date by ±1–2 weeks. Use this calculator for planning — then make the final call based on the trichomes.
Flushing before harvest
Many growers feed only pH-adjusted water for the last 1–2 weeks before harvest. The idea is to wash leftover nutrients out of the growing medium. In coco and hydro, most growers recommend a 1-week flush; in soil, 1–2 weeks. In living soil, flushing isn’t necessary and can even backfire.
What can go wrong when timing your harvest
- Relying on pistil color alone — brown hairs are a rough clue, not a precise indicator. Trichomes are more reliable.
- Harvesting too early out of impatience — immature buds deliver noticeably less potency and a harsh, unbalanced result.
- Treating the breeder’s flowering time as a fixed date — growing conditions regularly shift ripeness by one to two weeks.
- No loupe or microscope — without magnification, judging trichomes accurately is practically impossible. 60× is enough, 100× is better.
Harvest time — what growers want to know
How do I know when to harvest cannabis?
The most reliable indicator is the trichomes. Clear trichomes: not ripe yet. Cloudy trichomes: peak THC potency. 20–30% amber trichomes: balanced effect. Over 50% amber: stronger couch-lock. To judge them, you need a 60–100× loupe or a digital microscope.
What does an early vs. late cannabis harvest mean?
Early harvest (70–80% cloudy trichomes): more energetic, clear high, less body effect. Optimal harvest (80–90% cloudy, 10–20% amber): a balanced mix. Late harvest (30–50% amber): more sedating, more body feel. Which timing is right depends on the effect you want.
How long does cannabis flower, by strain type?
Indica-dominant strains: 7–10 weeks of flowering. Sativa-dominant strains: 9–14 weeks. Hybrids: 8–11 weeks. Autoflowers: 7–11 weeks from germination. Breeder figures always refer to flowering time from the flip to 12/12, not from germination.
When do I start counting flowering time?
For photoperiod strains: from the day you switch the light schedule to 12/12. For autoflowers: from the moment the first flower buds show (usually week 3–5 after germination).
Is trichome color the only indicator?
No. Other signs: pistil color (60–70% brown/orange), yellowing leaves, plump, dense calyxes and resin production. Still, trichomes are the most precise indicator — all other signs are secondary.
