Tools · Harvest timing
Harvest date calculator
for cannabis growers
Enter the day you flipped to 12/12, or the sprout date of an autoflower, and the breeder’s flowering time. Get the expected harvest window, when to start checking trichomes, and a calendar reminder.
Inputs
Plant type
Breeder flowering time (weeks)
The calendar is a guide. The trichomes decide: start checking two weeks before the window and chop on the ratio you want.
Result
Expected harvest window
Timeline
Method and sources. Window = start date + the breeder’s minimum to maximum weeks; first trichome check 14 days before the window opens. Photoperiod plants count from the switch to 12/12, autoflowers from the day the seedling emerges. Dates use your device’s time zone. A planning aid, not a prediction: harvest on the trichomes, see our cloudy vs amber guide.
How the calculator works
For photoperiod plants, flowering starts when you switch the lights to 12/12, so the breeder’s flowering time counts from the flip date. Autoflowers start flowering on their own, so their time is counted from the day the seedling breaks the soil. The calculator adds the breeder’s minimum and maximum to that date to give the window, and puts the first trichome check two weeks before it opens.
Treat the result as the moment to start looking, not the day to cut. Cultivar, light intensity, temperature, root space and stress all move the real date by a week or more in either direction.
What to look for once the window opens
| Target | Clear | Cloudy | Amber | Usually chosen for |
|---|---|---|---|---|
| Early | ~10% | ~85% | ~5% | Brighter, more uplifting |
| Balanced | 0–5% | ~80% | 10–20% | The most common target |
| Late | 0% | ~60% | 30%+ | Heavier, body-focused |
- Check the calyxes, not the sugar leaves. Sugar leaves amber earlier and make the plant look riper than it is.
- Sample top, middle and lower buds. Lower buds often lag a week behind the tops.
- Check every two days once most heads turn cloudy. The ratio can move fast near the end.
Learn to read the stages with our trichome chart and when to harvest cannabis by its trichomes. Growing autos? See autoflower harvest time.