Flowering is the payoff phase — the weeks when bud sites form, fatten, and frost over with trichomes. It’s also the phase with the least room for error: mistakes in light discipline, humidity, or feeding now cost you directly in the jar. Here’s how to run a clean flowering cycle from flip to ripeness.
Triggering flower
- Photoperiod strains (indoor): switch your timer to 12 hours on / 12 hours off. That’s the whole trick — the long dark period is the hormonal signal to bloom.
- Photoperiod (outdoor): nature flips the switch as days shorten after mid-summer.
- Autoflowers: nothing to do — they begin flowering at 3–5 weeks old on any schedule.
Dark means dark. Light leaks during the 12-hour night are the top cause of hermaphrodites (seeds in your buds) and re-vegging. Stand inside your dark tent: if you can see your hand, fix the leak.
The flowering timeline
- Weeks 1–3 — the stretch: plants can double in height while transitioning. Keep training/tucking through the stretch, then stop touching.
- Weeks 3–5 — bud set: real buds form at every site; pistils everywhere; the smell begins. Carbon filter time.
- Weeks 5–7 — bulk: buds fatten and stack; trichomes coat everything; humidity control becomes critical.
- Weeks 7–10+ — ripening: pistils darken and curl in, buds firm up, and you begin trichome checks (see the harvest guide). Sativas run longer than indicas — trust the plant, not the seed packet’s week count.
Feeding in flower
- Switch to a bloom formula — less nitrogen, more phosphorus and potassium (P-K drive bud development).
- Transition gradually over a week or two rather than switching cold.
- Some yellowing of lower fan leaves late in flower is normal senescence — the plant cashing in its savings. Yellowing at week 3 is a problem; at week 8 it’s the plan working.
- Ease feed strength down in the final two weeks; many growers finish with plain water.
Environment: mold’s window is open
- Humidity: 40–50%, lower by late flower. Dense buds + high humidity = botrytis (bud rot), the heartbreaker that ruins colas from the inside.
- Temperature: 65–80°F (18–26°C); slightly cooler nights late in flower deepen colors and preserve terpenes.
- Airflow: air should move through the canopy, not just around it. If your tent smells stale, mold agrees.
Watch for these
- Bananas/pollen sacs among pistils — a hermaphrodite. Remove them (or the plant) before they seed your whole room; then find the stress that caused it (usually light leaks or heat).
- Bud rot: a gray, brown-mush spot inside a fat cola. Cut well below it immediately and drop humidity.
- Foxtailing: spiky new growth on top of ripe buds — usually heat/light stress on the tops. Raise the light.
Flowering FAQ
How long does flowering take?
Most indicas and hybrids: 8–9 weeks after the flip. Sativas: 10–14. Autoflowers: total seed-to-harvest around 10–12 weeks. Every product page on our site lists the strain’s flowering time.
Can I look at my plants during the dark period?
Only with a green light — plants are effectively blind to green. White light during the dark cycle, even briefly and repeatedly, risks stress.
Should I flush before harvest?
Many growers water-only the final 1–2 weeks; whether it changes taste is debated, but easing off nutrients late is never harmful.
Next step: harvest
Pistils darkening, trichomes clouding — it’s decision time. Learn to read ripeness in the Harvest Timing Guide, or go back to the vegetative stage and the full Grow Guide.
Planning your next run? Shop strains by flowering time — every product page lists it.
