Cannabis Flowering Stage: Week by Week to Harvest
From switching the light cycle to the first cloudy (milky) trichomes — the flowering stage decides the yield and quality of your harvest.
The cannabis flowering stage week by week
The cannabis flowering stage starts with the switch to a 12/12 light cycle (for photoperiod strains) or automatically after 3–4 weeks (for autoflowers) and lasts 7 to 11 weeks, depending on the strain. During this time, the plant goes through several clearly distinct phases, and each one needs different care.
Early flowering (weeks 1–3): At first, the plant responds with one last growth spurt (the stretch) and forms its first preflowers, which reveal its sex. Your most important job here: spot male plants or hermaphrodites early, before they put your harvest at risk through pollination.
Mid flowering (weeks 4–6): The buds visibly get denser, and nutrient needs shift clearly toward phosphorus and potassium while the need for nitrogen drops. If you stick with your veg feeding schedule here, you risk nutrient toxicities and weaker buds.
Late flowering (week 7+): The trichomes — the resinous crystals on the buds — turn from clear to cloudy to amber. This color change is the most reliable indicator of the right harvest time, far more precise than the seed bank’s flowering time alone.
“In the last two weeks of flowering, don’t trust your naked eye — use a loupe. The difference between cloudy and amber trichomes decides the effect of your harvest.”
The flowering stage in detail
Light cycles for the start of flowering
Switching to 12/12 is what triggers the flowering stage — here’s how to set it up correctly and without light leaks.
Read article →
Mastering preflowers & the stretch
Preflowers kick off the stretch: how to tell the sex, plan enough space in time and adjust your care for the best results.
Read article →
Defoliation during flowering
Removing leaves selectively for more light on the buds and a bigger yield – the right timing decides between success and stress.
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Lollipopping done right
Removing lower, shaded shoots to send more energy to the main buds – how to do it and the best time in flowering.
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Autoflower flowering too early
Your plant stays tiny and is already flowering? The 5 most common causes and how to prevent it in your next grow.
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NPK chart for flowering
How nutrient needs shift between veg and flowering — with concrete guideline values for every week.
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Dosing nutrients correctly
The 7 most common dosing mistakes in flowering — and how to reliably avoid overfeeding or underfeeding.
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Avoiding popcorn buds
Small, airy buds instead of dense colas — the 5 most common causes and how to turn things around.
Read article →
Spotting foxtailing
Wispy, overly long bud tips — normal genetics or a sign of stress? How to tell them apart for sure.
Read article →
Few trichomes? Causes
When your buds sparkle less than expected — the most common reasons for weak trichome production.
Read article →
Finding your harvest window by the trichomes
The most precise way to know exactly when your plant is really ready to harvest.
Read article →
Avoiding an early harvest
The 5 most common signs of impatience — and why waiting almost always pays off.
Read article →Frequently asked questions about the cannabis flowering stage
How long does the cannabis flowering stage last?
Usually 7 to 11 weeks, depending on the strain. Sativa-dominant strains tend to take longer than indica-dominant ones — the seed bank usually lists the exact flowering time.
How can I tell the flowering stage has started?
By the first white hairs (pistils) at the branch nodes, usually 1–2 weeks after switching to 12/12. Before that, there’s often one last growth spurt (the stretch).
How much light does cannabis need during flowering?
Photoperiod strains need exactly 12 hours of light and 12 hours of uninterrupted darkness — even brief light leaks during the dark period can cause stress and hermaphrodites.
How high should humidity be during flowering?
Lower the humidity step by step to 45–55 % once flowering starts to minimize the risk of mold in the buds as they get denser. The climate overview shows you the right temperature and humidity values for every stage, plus the typical symptoms when they’re off.
How do I change feeding during flowering?
The need for nitrogen drops while phosphorus and potassium become more important. A dedicated bloom nutrient formula or a dose adjusted to the NPK chart makes more sense here than sticking with your veg feeding schedule.
What can I do about popcorn buds or few trichomes?
Both usually have the same causes: too little light, stress or not enough flowering time left. The linked in-depth articles walk you through the specific causes and fixes.
How do I know the right harvest time?
Most reliably by the trichome color under a loupe: clear means too early, cloudy is the most balanced time, and amber gives a more relaxing effect. Counting calendar days alone is far less accurate.
