Growing cannabis from seed takes 2 to 7 days to germinate and 3 to 5 months from sprout to harvest. Photoperiod strains flower only after you switch to 12 hours of light and 12 hours of dark, while autoflowering strains start flowering on their own about 3 to 4 weeks after sprouting. Success comes down to four things: good genetics, the right light cycle, correct pH, and clean water habits.
Cannabis grow timeline from seed
- Germination: 2 to 7 days
- Seedling: 1 to 3 weeks
- Vegetative: 3 to 8 weeks (longer for bigger plants)
- Flowering: 8 to 11 weeks
- Dry and cure: 3 to 6 weeks
Total time lands between 4 and 6 months for most photoperiod plants grown indoors. Autoflowers finish faster, in about 10 to 14 weeks from seed.
What do you need to grow cannabis from seed?
- Seeds, either photoperiod or autoflowering
- Containers with drain holes, 1 to 5 gallons
- Grow light (LED or HID) and a timer
- Soil, coco coir, or a hydro setup
- pH meter and nutrient kit
- Thermometer, hygrometer, and a small fan
Budget grows work in a closet with one LED panel and one plant. The gear you should not skip is a pH meter, a timer, and a way to move air.
How to Grow Cannabis Indoors: A Comprehensive Guide
Step 1: Germinate the seeds
Fold seeds into a damp paper towel, place the towel on a plate, and cover it to block light. Keep the towel moist and the temperature between 70°F and 80°F. A white taproot breaks through in 2 to 7 days.
A glass of water works too: soak the seed for 12 to 24 hours, then move it to paper towels. Plant the seed when the root reaches 1 to 2 cm, root tip down, about half an inch deep in moist medium.
Step 2: Seedling stage
Seedlings need light, warmth, and very little water. Run the light 18 hours on and 6 hours off, or 24 hours on for the first week to stop stretching.
Keep humidity near 60% to 70% and water in a ring around the stem so roots reach outward. Skip nutrients for the first 1 to 2 weeks if your soil already contains them.
Step 3: Vegetative stage
After 4 to 5 sets of true leaves appear, the plant enters vegetative growth. Keep the 18/6 light cycle and let it build stems and leaves for 3 to 8 weeks. Topping above the 4th or 5th node splits the main stem and creates two colas instead of one.
Target pH is 6.0 to 7.0 in soil and 5.5 to 6.5 in coco or hydro. Vegetative plants use more nitrogen than phosphorus or potassium. Water when the top inch of soil feels dry instead of following a fixed schedule.
Step 4: Flowering stage
Switch photoperiod plants to 12 hours of light and 12 hours of total darkness to trigger flower. Autoflowers flip on their own and need no light change. Most strains flower for 8 to 11 weeks.
Drop humidity to 40% to 50% to prevent bud rot, and shift nutrients toward phosphorus and potassium. Any light leak during the dark period can stall flowering or push a plant to grow male flowers. Seal the room and use a timer you trust.
Step 5: Harvest, dry, and cure
Look at trichomes with a jeweler's loupe or a phone microscope. Cloudy heads with a few amber ones mean peak potency for most strains, while clear heads mean the plant needs more time.
Hang branches in a dark room at about 60°F and 60% humidity for 7 to 10 days. Then cure the buds in glass jars for 2 to 4 weeks, opening each jar for a few minutes each day during the first week. Curing cuts the harsh chlorophyll taste and protects the cannabinoids you grew the plant for.
How do you tell male from female cannabis plants?
Female plants grow the flower you harvest; male plants grow pollen sacs and ruin a crop with seeds. Males show round sacs at the nodes, while females push out two white pistils. Check each plant every day once it hits 4 to 6 weeks of vegetative growth and remove any male before the sacs open.
What mistakes ruin a seed grow?
- Overwatering, which drowns roots and invites mold
- Full-strength nutrients on seedlings
- pH outside the 5.5 to 7.0 window, which locks out nutrients
- Light leaks during the 12-hour dark period
- Harvesting before trichomes turn cloudy
Most problems show up in the leaves first: yellow tips, curled edges, or dark spots. Watch the leaves each day and fix one variable at a time instead of changing everything at once.
Can you grow CBD hemp from seed at home?
Yes, where state law allows it. Hemp strains are bred for CBD and low THC, and the flower must test at 0.3% THC or less on a dry weight basis. Buy seeds from a seller that posts third-party lab results, because genetics set the ceiling on cannabinoid content.
Is it legal to grow cannabis from seed in the US?
Federal law permits hemp (cannabis at 0.3% THC or less) under the 2018 Farm Bill. Cannabis with higher THC remains illegal at the federal level, though many states allow home grows with plant limits. Check your state rules on plant count, licensing, and seed sourcing before you plant anything.