How to Grow Cannabis Indoors: A Complete Beginner's Guide
A first indoor grow takes roughly three to five months from seed to jar. This is the map of that journey, with links out to the detail for each stage. Home cultivation is only for adults in states and jurisdictions where it is legal — check your local rules first.
Phase 1: Set up before you plant
Tent, dimmable LED sized to it, inline fan and carbon filter, two circulation fans, a digital timer, fabric pots, medium, and pH and TDS meters. Run the whole setup empty for 24 hours and confirm temperature, humidity, and no light leaks.
Phase 2: Germination, 2-5 days
Soak seeds about 15 hours in room-temperature water in the dark, then move them into a damp paper towel kept dark at 70-80°F until a quarter-inch taproot appears. Plant taproot down, half an inch deep.
Phase 3: Seedling, 1-3 weeks
18/6 light, dimmed and hung high. 65-70% humidity, 72-78°F. Small waterings in a ring around the stem. No nutrients yet in good soil.
Phase 4: Vegetative, 3-8 weeks
18/6 light at full-ish power, 55-65% humidity, nitrogen-heavy feed. This is when you train: LST, topping, and filling your canopy. Veg until the plant fills 60-80% of your footprint.
Phase 5: Flower, 8-11 weeks
Flip to 12/12 with an absolutely dark night period. Expect the plant to stretch 50-100% in the first three weeks. Shift feed toward phosphorus and potassium, and drop humidity to 45-50% as buds fill.
Phase 6: Harvest, dry, cure
Harvest when trichomes are mostly cloudy with some amber. Dry 10-14 days at 60°F and 60% RH in the dark. Then cure in glass jars at 58-62% RH, burping daily for the first two weeks.
Frequently asked questions
- How long does a full grow take?
- Typically 14-20 weeks from seed to cured flower for photoperiods, and 12-16 weeks for autoflowers.
- What is the single biggest beginner mistake?
- Overwatering, followed closely by overfeeding. Both come from doing more rather than less.