Flowering stage, reading trichomes, and when to actually harvest

Photoperiod cannabis plants need a long uninterrupted dark cycle to start flowering. The standard trigger is to switch your lights from 18 hours on / 6 hours off to 12 hours on / 12 hours off. Once you flip, the plant senses the longer dark period and starts producing flowers within 1 to 2 weeks.

Autoflower strains do not need this. They flower on age alone, usually around week 4 to 5 from seed. If you are growing autos, you can leave the lights at 18/6 or 20/4 for the entire grow.

Week 1 to 2 (pre-flower stretch): the plant doubles or triples in height as it transitions. This is when training matters. You probably do not want to top now, only LST (low-stress training) and defoliation.

Week 3 to 5 (bud development): small white pistils thicken into visible bud sites. Smell intensifies sharply. Your carbon filter starts earning its money.

Week 6 to 7 (fattening): buds swell, trichomes fully form, and the plant draws more phosphorus and potassium. This is when most strains pack on the bulk.

Week 8 to 10 (ripening): pistils start to curl in and darken, leaves yellow, and trichome heads change color. This is the window where harvest decisions live.

Trichomes are the mushroom-shaped resin glands on the buds. You need a jeweler's loupe (10x to 60x) or a USB microscope to see them clearly. They cycle through three colors.

Clear: not ready. Cannabinoids still developing. Harvesting now produces a thinner, more racy effect with less body and lower potency.

Milky/cloudy: peak THC. Most growers chase this color. The effect is balanced, full-bodied, neither racy nor heavy.

Amber: THC is degrading to CBN, the sedative cannabinoid. The high becomes heavier, more couch-locking. About 10 to 20% amber on top of mostly cloudy is the most common harvest target.

Look at the trichomes on the buds themselves, not on the sugar leaves. Sugar-leaf trichomes mature faster and will mislead you.

Flush the plant with plain pH-adjusted water (no nutrients) for the final 7 to 14 days. The reasoning is debated, but the practice is widespread and removes any nutrient salts that affect taste in the cured bud. Cut the lights off entirely for 24 to 48 hours before chop. Some growers claim this triggers a final trichome push. Evidence is anecdotal but the cost is zero.

Cut the plant at the base. Hang whole plants or break into branches and hang upside down in a dark, 60 to 70°F room at 55 to 65% humidity. Drying takes 7 to 14 days depending on density. The branches should snap, not bend, when ready. Then trim and move to curing jars.