You can grow cannabis at home if your state allows it. Hemp with 0.3 percent THC or less is legal under federal law. Marijuana is not. A home grow needs four things: a light schedule, a pH range, moving air, and a dry room.
How Long Does It Take to Grow Cannabis?
Start With State Law
The 2018 Farm Bill legalized hemp production. Hemp is Cannabis sativa at 0.3 percent THC or less on a dry weight basis. Home growing of marijuana stays illegal under federal law. States set their own plant counts. Some states allow 2 to 12 plants for adults. Some allow medical patients. Some ban home grows. Read your state statute before you buy a seed.
Pick the Plant Type
Photoperiod
Photoperiod plants flower when the light cycle drops to 12 hours on, 12 hours off. Vegetative growth runs at 18 hours on, 6 hours off. Seed to harvest takes 12 to 16 weeks. You control the flip date.
How to Grow Cannabis from Seed: Step-by-Step Guide
Autoflower
Autoflower plants flower on an internal timer, not the light cycle. Run 18 to 20 hours of light per day from seed to harvest. Cycle length is 9 to 11 weeks. Plants stay short. Yield per plant is lower.
Set Up the Space
- Tent: 2 by 4 feet holds 2 to 4 plants. 4 by 4 feet holds 4 to 6.
- Light: LED at 30 to 40 watts per square foot. A 4 by 4 tent needs 480 to 640 watts at the wall.
- Air: exhaust fan at 100 to 200 CFM for a 4 by 4 tent. One full air exchange per minute.
- Container: 3 to 5 gallon fabric pots.
- Medium: peat or coco mix. Soil pH 6.0 to 6.8. Coco pH 5.8 to 6.2.
- Water: 5 to 10 percent of pot volume per feed.
- Temperature: 70 to 82 F in veg. 65 to 78 F in flower.
- Humidity: 60 to 70 percent in veg. 40 to 50 percent in flower.
Feed the Plant
Veg formula carries more nitrogen. A ratio near 3-1-2 works. Flower formula carries more phosphorus and potassium, near 1-3-2. Start at half the label rate. Measure pH after mixing. Check runoff EC if leaf tips burn or curl.
Flower and Harvest
Photoperiod plants flower for 8 to 11 weeks. Check trichomes with a 30x loupe. Clear trichomes mean the plant is early. Cloudy trichomes mean peak THC. Amber trichomes mean THC is breaking down into CBN. Hemp growers harvest when trichomes turn cloudy and THC holds under 0.3 percent. That number comes from a lab test, not a guess.
Dry and Cure
Dry at 60 F and 60 percent humidity for 7 to 10 days. Stems should snap, not bend. Cure in glass jars at 62 percent humidity for 2 to 4 weeks. Burp the jars once a day for the first week. Store flower in the dark at 60 to 70 F. Light and heat degrade cannabinoids over months.
CBD Notes
CBD hemp cultivars carry high cannabidiol and low THC. Labs test with HPLC or gas chromatography. THC rises as flowers mature, so a late harvest can push a plant over the legal limit. Test at 30 days before harvest and again on harvest day.