Cannabis cultivation is the process of growing cannabis plants from seed (or clone) through harvest, then drying and curing the flowers for consumption. A single grow cycle typically takes 3 to 6 months depending on the strain, growing method, and whether you’re working indoors or outdoors. The process involves managing light, nutrients, temperature, and humidity through distinct growth stages, each with its own requirements.
Growth Stages and Timeline
Cannabis moves through five recognizable stages, each demanding different care. Germination comes first and takes 3 to 10 days. Seeds are placed in a moist environment until a small root (called a taproot) emerges and pushes into the growing medium. From there, the plant enters the seedling stage for 2 to 3 weeks, producing its first sets of iconic fan leaves.
The vegetative stage follows and lasts anywhere from 2 to 8 weeks. This is when the plant builds its structure: stems thicken, branches multiply, and the root system expands rapidly. Indoor growers control how long this phase lasts by manipulating light schedules, which directly affects final plant size. After a brief pre-flowering transition of 1 to 2 weeks, the flowering stage runs 6 to 8 weeks. This is when the plant produces the resinous buds that are ultimately harvested.
Photoperiod vs. Autoflowering Strains
One of the first decisions a grower makes is choosing between photoperiod and autoflowering genetics, because each type responds to light differently and shapes the entire growing approach.
Photoperiod strains flower based on how many hours of darkness they receive. Indoors, growers keep lights on 18 to 24 hours a day during the vegetative stage so the plant “thinks” it’s summer and keeps growing bigger. When it’s time to trigger flowering, they switch to a strict 12 hours on, 12 hours off schedule, simulating autumn. If photoperiod plants never get those long dark periods, they’ll continue producing stems and leaves indefinitely. Plants typically double in size after this light switch, so growers need to plan for that stretch.
Autoflowering strains, bred from a wild subspecies adapted to short northern summers, begin flowering automatically about four weeks after germination regardless of light schedule. Most growers keep them under 18 to 24 hours of light for the entire grow, since more light generally means faster growth. Autoflowers finish quicker and stay smaller, making them popular with beginners and growers working in tight spaces. The trade-off is less control over plant size and, historically, slightly lower potency, though modern breeding has narrowed that gap considerably.
Identifying Male and Female Plants
Only female cannabis plants produce the resinous flowers growers are after. Male plants produce pollen sacs instead, and if they pollinate females, the resulting buds fill with seeds, which drastically reduces quality. Identifying and removing males early is one of the most important skills in cultivation.
The earliest visual clue appears as “pre-flowers” between the fourth and sixth nodes of the plant. Male pre-flowers show up about three to four weeks after germination as tiny, smooth, egg-shaped sacs. Female pre-flowers emerge slightly later, between four and six weeks, as small V-shaped structures with white or pink hairs. Beyond pre-flowers, males tend to grow taller with thicker stems and fewer branches, while females stay shorter and bushier with denser foliage. Many growers skip this guesswork entirely by purchasing feminized seeds, which are bred to produce only female plants.
Light Requirements
Light is the engine of cannabis growth, and indoor growers measure its intensity using a unit called PPFD (photosynthetic photon flux density), which quantifies how much usable light actually reaches the plant canopy. The optimal ranges shift upward as the plant matures: seedlings do best at 200 to 400 μmol/m²/s, vegetative plants at 400 to 600, and flowering plants at 600 to 900. Pushing light too high during early growth can stress young plants, while insufficient light during flowering limits bud development.
LED fixtures have largely replaced older high-pressure sodium and fluorescent setups in modern grows. They produce less heat, use significantly less electricity, and can be tuned to specific light spectrums. One large commercial operation, for example, saved over 258,000 kilowatt-hours annually just by switching from fluorescent to LED tubes in a single vegetative room. Indoor electricity costs run roughly $0.24 per gram of dried flower, compared to about $0.01 per gram for outdoor cultivation, making lighting choices one of the biggest factors in operational cost.
Nutrients Through Each Stage
Cannabis is a hungry plant, and its nutritional needs flip between stages. The three primary nutrients are nitrogen, phosphorus, and potassium, often written as an N-P-K ratio on fertilizer labels.
During the vegetative stage, the plant is building leaves, stems, and roots, so it needs a nitrogen-heavy ratio of roughly 3:1:2 (nitrogen:phosphorus:potassium). Once flowering begins and the plant shifts its energy toward bud production and resin, phosphorus and potassium take priority. Early and mid-flower calls for a ratio around 1:3:2, and during the final ripening weeks, growers often move to 0:2:3, essentially dropping nitrogen altogether. Overfeeding or using the wrong ratio at the wrong time leads to nutrient burn (browning leaf tips) or deficiencies that stunt growth and reduce yields.
Beyond the big three, cannabis also needs calcium, magnesium, sulfur, and trace minerals like iron and zinc. Soil-based grows tend to be more forgiving because organic matter buffers nutrient delivery, while hydroponic setups offer more precision but less room for error.
Common Pests and Diseases
Two fungal pathogens cause the most damage in cannabis production. Powdery mildew appears as a white, dusty coating on leaves and spreads through airborne spores or infected clones. Botrytis, commonly called bud rot, attacks the dense flower clusters from the inside out and can cause significant losses both during production and after harvest in storage. Both are difficult to manage once established, which is why prevention through airflow, humidity control, and sanitation matters more than treatment.
Below the soil line, root pathogens like Fusarium and Pythium cause browning and decay that leads to stunted growth, yellowing leaves, and sometimes plant death. These organisms thrive in overwatered, poorly drained conditions. Spider mites, fungus gnats, and thrips are the most persistent insect pests, especially indoors where natural predators are absent. Integrated pest management, using beneficial insects, sticky traps, and environmental controls rather than chemical sprays, has become standard practice in quality-focused operations.
Indoor, Outdoor, and Greenhouse Growing
Each growing environment comes with distinct advantages. Outdoor cultivation relies on sunlight and natural seasons, keeping costs low (electricity runs about $0.01 per gram) but limiting growers to one or two harvests per year depending on climate. Plants grow larger outdoors, sometimes exceeding six feet, but they’re exposed to weather, pests, and theft.
Indoor cultivation offers total environmental control: light schedules, temperature, humidity, and CO2 levels can all be dialed in precisely. This allows year-round harvesting and consistent quality, but electricity costs are roughly 24 times higher than outdoor growing. Greenhouse cultivation splits the difference, using natural sunlight supplemented by artificial lighting and climate controls. Electricity costs for greenhouse grows average around $0.21 per gram, a meaningful savings over fully indoor operations.
Drying and Curing After Harvest
What happens after harvest matters as much as what happens during growth. Freshly cut cannabis contains roughly 75% water and needs to be dried slowly to preserve the compounds that determine flavor, aroma, and potency. The ideal drying room sits between 55 and 65°F with relative humidity between 50 and 60%. This slow approach typically takes 7 to 14 days. Rushing the process with high heat or low humidity traps moisture inside the buds, creating conditions for mold, or dries the outer layers too fast while the interior stays damp.
Curing follows drying and involves storing trimmed buds in sealed containers, opening them periodically to exchange air. This process, which lasts a minimum of two to four weeks (though many growers cure for two months or longer), allows remaining moisture to distribute evenly and lets chlorophyll break down. Properly cured cannabis smokes smoother, smells more complex, and stores longer without degrading. Trimming areas should match the same temperature and humidity conditions as the drying room to avoid shocking the plant material during handling.