The flowering phase is the most exciting part of the cannabis cycle. After weeks of growth, the plant finally begins to show its worth: the formation of buds, trichomes, and aromatic resin. For growers—both beginners and experienced—understanding the flowering week by week is essential for achieving a healthy, high-quality harvest.
🌿 Introduction: transition from growth to flowering
The flowering phase begins when the light cycle changes from 18 hours of light / 6 hours of dark to 12 hours of light / 12 hours of dark (for photoperiod plants). Autoflowering varieties flower automatically after about 3 to 4 weeks, regardless of the light schedule.
Total flowering time varies by variety, but is usually between 7 and 10 weeks.
🌼 Week 1 – The transition phase (stretching phase)
In the first week, the plant responds to the change in light cycle. It begins to grow rapidly—sometimes doubling in height!
What's happening:
Strong growth in stems and branches (“stretch”).
The first signs of flowering (small white hairs, pistils) appear on the buds.
The plant consumes more nitrogen (N) and potassium (K).
Tips:
Continue to give some growth nutrients, but start gradually with flowering nutrients.
Make sure the branches have enough space — they will stretch even further.
🌸 Week 2 – First flower development
The first real flowering symptoms become visible: clusters of white hairs (pistils) form at the buds and axils.
What's happening:
The stretch is slowly slowing down.
Small flower buds are forming.
The scent becomes slightly perceptible.
Tips:
Do not increase the humidity too much (around 50–55%).
Support fast-growing branches to prevent breakage.
🌺 Week 3 – Beginning of bud formation
Now the plant really begins to concentrate on forming buds. The white hairs become more numerous, and compact clusters begin to appear.
What's happening:
The flowering has now clearly started.
The plant usually stops stretching.
The need for phosphorus (P) and potassium (K) increases.
Tips:
Now use only flowering nutrients.
Check carefully for mold or insects — the buds will become denser.
🌻 Week 4 – Thickening of the buds
The buds become thicker and firmer. The aroma intensifies, and trichomes (tiny resin crystals) begin to appear.
What's happening:
Buds grow quickly in volume.
Terpene production begins (fragrances).
Energy goes entirely to flower development.
Tips:
Keep the temperature stable (around 24–26 °C during the day, 18 °C at night).
Avoid overfeeding; check EC values regularly.
🌼 Week 5 – The intensive flowering phase
The plants are now at their peak. The buds are swelling, resin production is increasing, and the aroma is strong.
What's happening:
Trichomes become visible as a shiny layer.
Pistils are starting to darken slightly.
Weight gain in the buds.
Tips:
Check air circulation to prevent mold.
Avoid too much moisture in the air (<50%).
If necessary, support branches with nets or sticks.
🌷 Week 6 – Maturation of the buds
The plant stops growing and focuses on ripening its buds. Resin production reaches its peak.
What's happening:
Trichomes fill with cannabinoids (THC, CBD).
Pistils turn orange or brown.
The scent is intense and characteristic.
Tips:
Check trichomes with a magnifying glass (they should still be clear).
Start by lowering nitrogen.
🌾 Week 7–8 – Final flowering and ripening
The plant is preparing for harvest. Trichomes change from clear to milky and then to amber—the signal that harvest time is near.
What's happening:
Growth stops completely.
THC level reaches its maximum.
Most leaves start to turn yellow (natural process).
Tips:
Flush the medium with clean water to remove salts.
Avoid stress: do not prune or move.
Check the trichomes daily to determine the correct harvest time.
🌿 Week 9–10 – Harvest Time
When 70–90% of the trichomes are milky and 10–20% are amber, the plant is ready for harvest.
What's happening:
The plant loses its shine.
Buds are compact, sticky and heavy.
Harvest tips:
Cut the plant in a dark place with good ventilation.
Allow the buds to dry slowly (50% RH, 18–20 °C).
Then let them cure for 2–4 weeks in airtight jars for optimal flavor.