Cannabis flowering lasts about 8 to 10 weeks for most photoperiod strains, moving from the week 1 stretch through bud set, swelling, and ripening before harvest. Timing is confirmed by trichome color and pistil recession rather than by the calendar alone. Autoflowering cultivars compress the same sequence into a fixed window of roughly 70 to 90 days from seed.
What happens week by week in the flowering stage?
- Week 1 to 2: vertical stretch, node spacing widens, first pistils appear at bud sites.
- Week 3 to 4: bud set, calyxes cluster, resin glands become visible under magnification.
- Week 5 to 6: rapid bud swell, flower mass and density increase, aroma peaks.
- Week 7 to 8: ripening, pistils darken and curl inward, trichomes turn cloudy.
- Week 9 to 10+: harvest window for most strains, with late sativas running longer.
Weeks 1 and 2: the stretch
Plants can double in height during the first two weeks after the light flip. Growers who train low or use a tent with limited headroom often flip earlier to control the stretch. Light leaks during this window can stall flower initiation and push the whole timeline back.
how long does flowering stage last
Weeks 3 and 4: bud set
Pistils multiply at each node and the plant shifts energy from stems to flowers. Phosphorus and potassium demand rises while nitrogen needs fall, so many feeding charts switch to a bloom formula here. Defoliation at this point should stay light, because heavy leaf removal slows bud development.
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Weeks 5 and 6: swelling
Buds gain most of their final weight in this stretch. Colas fill in, internodes tighten, and terpene production climbs. Environment matters more than additives now: stable temperature, moderate humidity, and steady airflow reduce mold risk on dense flowers.
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Weeks 7 to 9: ripening
Pistils shift from white to orange or brown and curl toward the calyx. Trichomes progress from clear to cloudy to amber, which is the most reliable ripeness signal. Most growers harvest when trichomes are mostly cloudy with a small share of amber.
How do you know when to harvest?
Check trichomes on the calyxes, not on sugar leaves, with a loupe or USB microscope. Clear trichomes mean immature, cloudy means peak THC, and amber means degrading THC with more sedative effects. Breeder timelines are estimates, so the plant decides the final date.
Does convenience change the flowering calendar?
Convenience has become the deciding factor for many home growers, and it shows up in the flowering stage. Autoflowers skip the light flip and finish on a predictable clock, which suits small tents and irregular schedules. Pre-flowered clones, controller-run environments, and at-home potency tests shorten the guesswork that once stretched harvests by weeks.
What shortens or lengthens flowering?
- Genetics: indica-leaning lines finish faster than equatorial sativas.
- Light schedule: a steady 12/12 photoperiod keeps flowering on track.
- Stress: heat, drought, and light leaks delay maturation.
- Environment: cool root zones and low humidity can slow bud swell.
How long should you flush before harvest?
Many growers reduce nutrient strength for the final 7 to 14 days and water with plain pH-adjusted solution. The practice aims to improve flavor, though results vary by medium and cultivar. Track trichomes daily in the last two weeks so a flush schedule never overrides ripeness.