How to grow cannabis at home in California, from seed to harvest

Here is how to grow cannabis at home in California in one paragraph. If you are 21 or older, you can keep up to six living plants in a locked space at your home. Start them from seed or a rooted clone, give them about 18 hours of light a day while they grow, then switch photoperiod plants to 12 hours of light and 12 hours of uninterrupted darkness to flower. Harvest, dry slowly in the dark, and store the buds in airtight jars. Using the stage lengths published by the University of Saskatchewan gardening program, a photoperiod grow runs roughly four to five months from seed to dried flower.

You do not need a greenhouse. A small tent with an exhaust fan, an LED fixture on a timer, a few pots of good potting mix and a cheap thermometer and humidity meter will carry a first grow. Our guides to buying seeds in California, growing a dispensary clone and topping versus LST each go deeper on one stage.

Last reviewed: November 2026.

California's home-grow rule: six plants, locked and out of sight

California’s rule is in Health and Safety Code section 11362.2. Subdivision (a)(3) allows adults 21 and over not more than six living plants within a single private residence, or on its grounds, at one time. That is six per home, not six per adult. Subdivision (a)(2) says the plants, and any harvest above 28.5 grams, must be kept in a locked space that is not visible from a public place. The Judicial Council’s Prop 64 guide for judges notes that growing six or fewer plants in view or unlocked is an infraction with a $250 fine.

Medical patients can grow more if their physician recommends it, according to the Department of Cannabis Control. Under section 11362.2(b), cities and counties cannot ban indoor home grows but can ban outdoor ones, and DCC notes some require permits, so check your city or county website before you buy a tent. If you rent, read the lease. DCC also bars volatile solvents such as butane or propane if you turn your harvest into a product at home. Reading this in Portland? OLCC allows four plants per residence in Oregon, however many adults live there. This is general information, not legal advice.

In practice, a lockable closet or tent in a room that children and pets cannot reach covers all of this. It also keeps odor, water and electrical cords in one place you control.

How to grow cannabis, stage by stage

A photoperiod cannabis plant passes through five stages: germination, seedling, vegetative growth, flowering and drying. Each wants its own light schedule and slightly different air. The table below uses the University of Saskatchewan’s published ranges. Plants tolerate a little drift outside them, but these are the university’s targets.

Autoflowering plants run on a different clock. The university’s flowering guide says they begin flowering on their own after about four to five weeks of total growth, whatever the light, and indoor growers often keep them under 18 hours of light from start to finish. Seed packets print an expected flowering time; USask calls those very general guidelines at best.

Seeds or a clone: choosing your starting plant

Seeds give you a taproot and the full life cycle. USask’s germination guide suggests soaking seeds for 12 to 16 hours (never more than 24), then planting about 1 cm deep in a medium kept moist but not soaking. Regular seeds can grow into males or females, feminized seeds are bred to produce females, and autoflowers flower by age instead of day length.

A rooted clone skips germination and the seedling stage, which happen only once in a plant’s life. Under California’s DCC regulations (section 15408), licensed retailers may sell immature plants and seeds only from a licensed nursery or microbusiness, and the plant must be non-flowering and shorter and narrower than 18 inches. Clones copy their mother’s problems along with her genetics: Oregon State University Extension notes that hop latent viroid spreads through cuttings from infected mother plants, often without obvious symptoms on young plants. Keep a new clone apart from other plants for its first days. Our guide to taking your own cuttings covers the next step.

Set up the space before the plant arrives

Run the room empty for a day first. Hang the light, set the timer, switch on the exhaust fan and read temperature and humidity at leaf height with the lights on and off. USask’s vegetative guide says most modern LEDs sit 20 to 30 cm (8 to 12 inches) above the tops of growing plants, and seedlings start around 30 cm under an LED. A closed tent heats up fast if the fan fails, so check it daily.

Use pots with drainage holes, a commercial potting mix (read whether it already contains fertilizer) and a tray to catch runoff. Follow the fixture maker’s electrical instructions, keep water away from plugs, and have an electrician look at anything beyond plugging into an outlet. A carbon filter on the exhaust tames the odor, which climbs sharply once buds form.

Seedlings and vegetative growth: water by weight

Seedlings want small amounts of water often. The USask seedling guide describes the right medium as a damp sponge, wet but not dripping, and says fertilizer can usually wait a week or two; when you start, use half or even quarter strength. Long, floppy stems mean the light is too weak or too far away.

Once the plant is growing hard, lift the pot. USask’s rule of thumb is to water when the pot weighs about half what it did fully soaked, with a little runoff to stop salts building up. Indoors, the university suggests water between pH 6.2 and 6.8 and an all-purpose fertilizer such as a 20-20-20 mix. Move the plant into its final pot during this stage, because transplanting once it flowers stresses it.

At about four to five weeks of total growth, check the top few nodes for pre-flowers. A teardrop shape with a white hair is female; a rounded head on a thin stalk is male. Remove males if you want seedless flower. This is also when growers top or bend plants to widen the canopy, which our guides to topping versus LST and pruning explain, with the grower’s glossary for the jargon.

Flipping to flower and keeping the dark period dark

To flower a photoperiod plant, set the timer to 12 hours on and 12 off and leave it there until harvest. The dark has to be complete. Plants stretch in the first weeks of flower, sometimes a lot, so leave headroom under the light. USask advises against pruning branches early in flower because it can add to the stretch.

Feeding shifts toward phosphorus and potassium (the university mentions ratios like 15-30-15), and many growers stop fertilizing for the last one to two weeks. The biggest late-flower risk is gray mold inside dense buds, which is why USask lowers its humidity target to 35 to 45% in late flower. A power cut that stops the fan can spike humidity quickly.

Check leaf undersides and the soil surface every few days. UC IPM lists spider mites and fungus gnats among common indoor plant pests and notes that overwatering and poor drainage help gnats multiply. Before you spray anything, check that the product meets California criteria for legal use on cannabis. A natural label alone does not qualify it.

Harvest, dry and store

USask’s harvest-timing guide says most varieties are ready about 8 to 10 weeks after flowering starts. Signs include yellowing leaves, a plant that drinks less and buds that stop swelling. Look at the trichome heads with a 16x loupe in several spots: clear means not yet, cloudy is where some studies find peak cannabinoid content, and amber means some THC is breaking down. Brown hairs alone are a weaker signal, and the author calls the idea that trichome color changes the effect anecdotal.

Cut branches 15 to 60 cm long and trim them now (wet) or after drying (dry); the USask trimming article treats both as fine. Then dry them in the dark at 16 to 23°C and 50 to 60% humidity, with a small fan moving air past the buds but not onto them. A wet-trimmed harvest takes 10 to 14 days. It is done when branches have lost about 75% of their original weight and small stems snap instead of bending. Watch for mold in the first four to six days.

Store the dried buds in airtight glass jars somewhere dark, and keep a small everyday jar so the main one stays closed. The university’s storage guide has a simple test: if you can smell it, the container is not airtight. Home-grown flower has no lab test behind it, so throw out anything that looks or smells moldy.

Frequently asked questions

Sources

• California Health and Safety Code section 11362.2
• OLCC: Recreational marijuana FAQ
• DCC: What's legal
• Judicial Council of California: Prop 64 guide (Couzens and Bigelow)
• DCC: Text of regulations (section 15408)
• USask: Cannabis gardening overview
• USask: Germination
• USask: Seedlings
• USask: Vegetative growth
• USask: Flowering
• USask: Harvest timing
• USask: Harvesting and trimming
• USask: Drying cannabis
• USask: Storing your cannabis
• OSU Extension: Hop latent viroid in hemp
• UC IPM: Houseplant problems
• California DPR: Pesticide products legal for use on cannabis

For adults 21+ (18+ with a physician’s recommendation in California). Keep out of reach of children and pets. Do not drive or operate machinery after use.