Cannabis flowering runs 6 to 10 weeks for most photoperiod cultivars and moves through four phases: stretch in weeks 1 to 2, early bud set in weeks 3 to 4, swelling in weeks 5 to 6, and ripening in weeks 7 to 10. Autoflowering and CBD hemp varieties often finish on the shorter end, while sativa-dominant plants can run 11 to 14 weeks. The timeline below describes what the plant is doing each week and what growers normally adjust along the way.
How long does the cannabis flowering stage last?
Flowering begins when the light cycle shifts to 12 hours on and 12 hours off for photoperiod plants, or automatically at a set age for autoflowers. Total duration depends on genetics, environment, and grow style.
- Indica and indica-dominant hybrids: 7 to 9 weeks
- Sativa and sativa-dominant hybrids: 10 to 14 weeks
- Autoflowers: 8 to 10 weeks from seed to harvest, with 5 to 7 of those weeks in flower
Cannabis flowering stage week by week
Weeks 1 to 2: Transition and stretch
The plant stops vertical leaf growth and starts stretching, sometimes doubling in height. Bud sites form as small clusters at the nodes, and pre-flowers show sex. Most growers keep nitrogen in the feed and hold off on heavy bloom boosters.
Weeks 3 to 4: Early bud formation
Flower clusters thicken and white pistils push out along the stems. Stretch slows, and the canopy shape becomes clear. This is the window for defoliation, trellising, and switching to a lower-nitrogen, higher-phosphorus and potassium feed.
How Long Does the Cannabis Flowering Stage Last?
Weeks 5 to 6: Mid-flower swelling
Buds gain most of their mass here, and trichomes become visible under magnification. Resin production climbs as cannabinoids and terpenes accumulate in the glandular heads. Humidity is usually kept near 40 to 50 percent to lower mold risk as flowers pack together.
Weeks 7 to 8: Ripening
Pistils turn orange or brown and curl inward toward the bud. Trichomes shift from clear to cloudy, the stage tied to peak THC and CBD levels in most cultivars. Many growers begin flushing and stop feeding nitrogen.
Weeks 9 to 11: Late flower and harvest window
Long-flowering sativas and some CBD hemp lines finish in this range. Buds stop swelling, fan leaves fade, and cloudy trichomes turn amber as THC degrades toward CBN. Waiting past this point trades potency for a heavier effect.
How do you know when to harvest?
Breeder timelines are estimates, so check the plant itself rather than the calendar.
- Trichomes: clear means early, cloudy means peak potency, amber means past peak
- Pistils: about 70 to 90 percent darkened and curled for most THC cultivars
- CBD hemp: harvest when trichomes are mostly cloudy for the highest CBD content, before amber develops
What should you change during flowering?
Small environment shifts protect yield and quality through the final weeks.
- Light: strict 12/12 for photoperiod plants, with no light leaks during the dark period
- Temperature: 68 to 78 F during the day, cooler at night to support terpene retention
- Humidity: 55 to 65 percent early, dropping to 40 to 50 percent by mid-flower
- Nutrients: lower nitrogen, steady phosphorus and potassium, and a plain-water flush in the last 7 to 14 days
Do CBD hemp plants flower on the same schedule?
Yes, hemp follows the same photoperiod trigger and the same stretch, bud set, and ripening sequence. The main difference is the harvest target: CBD cultivars are cut when trichomes are cloudy and pistils are still partly white, which preserves cannabinoid content and limits THC development. Field-grown hemp is often harvested earlier than indoor cannabis for that reason.