Cannabis Grow Schedule Planner
Generate a personalized week-by-week grow schedule with environment targets, nutrient phases, light schedules, and training tips. Works for photoperiod and autoflower strains in any medium.
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How Long Does It Take to Grow Cannabis from Seed to Harvest
The total time from seed to smokable cannabis depends on strain type, growing method, and environment. Here are the typical ranges:
- Indoor photoperiod: 3 - 5 months (12 - 20 weeks). You control the vegetative length, and flowering typically takes 8 - 10 weeks. Longer veg means bigger plants and higher yields but a later harvest.
- Indoor autoflower: 2 - 3 months (8 - 12 weeks). The plant transitions to flower automatically based on age, making the total time fixed regardless of light schedule.
- Outdoor photoperiod: 4 - 6 months. Plants veg through spring and summer, then flower as daylight hours decrease in late summer and fall. Harvest typically falls in September - November depending on latitude.
After harvest, add 1 - 2 weeks for drying and at least 2 - 4 weeks of curing for proper flavor and smoothness. Rushing the dry or cure is the most common mistake new growers make.
Autoflower vs Photoperiod Growing Timeline
Choosing between autoflower and photoperiod genetics fundamentally changes your grow schedule. Here is a side-by-side comparison:
| Factor | Photoperiod | Autoflower |
|---|---|---|
| Total Time (seed to harvest) | 12 - 20 weeks | 8 - 12 weeks |
| Veg Control | Full control — veg as long as you want | None — plant auto-transitions |
| Light Schedule | 18/6 veg, 12/12 flower | 20/4 or 18/6 throughout entire life |
| Average Yield | 100 - 300 g per plant (indoor) | 50 - 150 g per plant (indoor) |
| Difficulty | Moderate — requires light schedule management | Easy — plant and wait |
| Best For | Maximizing yield, cloning, experienced growers | Fast harvests, beginners, stealth grows |
Week by Week Cannabis Growing Guide
Every cannabis grow follows the same fundamental phases, though timing varies by strain type and method. Here is a summary of each major stage and its key milestones:
- Germination (3 - 7 days): Seeds soak, crack open, and send out a taproot. Maintain warmth (75 - 78 °F) and moisture. The seed should be planted taproot-down once the root is 0.5 - 1 inch long.
- Seedling (Weeks 1 - 2): The first round leaves (cotyledons) appear, followed by the first true serrated leaves. Light should be gentle, nutrients minimal, and humidity high (65 - 70 %). This is the most fragile stage.
- Vegetative (Weeks 3 - 8+): Rapid growth phase where the plant builds its structure. This is when you train the plant (topping, LST, SCROG) to maximize future bud sites. Increase light intensity and nutrient strength progressively.
- Transition / Stretch (1 - 2 weeks): After flipping to 12/12 (photoperiod) or when the plant auto-transitions, expect a dramatic height increase of 50 - 100 %. Switch to bloom nutrients and make final canopy adjustments.
- Flowering (Weeks 1 - 8+): Buds form, swell, and ripen. Early flower shows pistils and bud site development. Mid flower sees rapid bud growth and trichome production. Late flower is the ripening phase where nutrients are reduced and flushing begins.
- Harvest, Dry, and Cure (4 - 6 weeks): Harvest at peak trichome maturity. Dry slowly in a controlled environment for 7 - 10 days. Cure in glass jars for 2 - 4+ weeks to develop flavor, smoothness, and potency.
Key Milestones in the Cannabis Growth Cycle
Knowing what to look for at each stage helps you stay on track and catch problems early. These are the critical milestones every grower should monitor:
- First true leaves: Appearing a few days after the cotyledons, the first serrated leaves indicate the plant is photosynthesizing on its own. You can begin very light feeding at this point.
- First topping: Once the plant has 4 - 6 nodes (usually week 3 - 4 of veg), you can top it by cutting above the 4th or 5th node. This creates two main colas and triggers bushier growth. Do not top autoflowers.
- Pre-flower signs: Small pistils (white hairs) or pollen sacs appear at the nodes where branches meet the main stem. For photoperiods, this usually shows 1 - 2 weeks after flipping to 12/12. For autos, it appears around weeks 3 - 4 from seed.
- Pistil development: Dense clusters of white pistils mark active bud sites. As flowers mature, pistils darken to orange or brown and curl inward. When 70 %+ of pistils have changed color, harvest is approaching.
- Trichome changes: Use a 60x loupe to check trichome heads on the buds (not sugar leaves). Clear trichomes mean the plant is not ready. Milky-white trichomes indicate peak THC. Amber trichomes signal THC degradation into CBN, producing more sedative effects. Most growers harvest at 80 - 90 % milky with 10 - 20 % amber.
- Harvest window: The ideal harvest window is typically 5 - 10 days long. Harvesting early yields a more cerebral, energetic high. Harvesting late produces heavier, more body-focused effects. Check trichomes daily during the last two weeks to hit your preferred ratio.
Frequently Asked Questions
How long does it take to grow cannabis indoors?
Most indoor cannabis grows take 3 to 5 months from seed to harvest. Autoflowers finish fastest at 8 - 12 weeks total. Photoperiod strains need 4 - 8 weeks of vegetative growth plus 8 - 10 weeks of flowering, putting them at 14 - 20 weeks on average. Add 1 - 2 weeks for drying and 2 - 4 weeks for curing before the flower is ready to consume.
When should I switch to 12/12 for flowering?
Switch photoperiod plants to a 12/12 light schedule when they have filled roughly 60 - 70 % of your canopy. Plants stretch 50 - 100 % during the first two weeks of flower, so they will fill the remaining space. Most growers veg for 4 - 8 weeks before flipping. If you are using a SCROG net, flip when 70 - 80 % of the net squares are filled.
How do I know when cannabis is ready to harvest?
Check the trichomes with a jeweler's loupe or digital microscope. When most trichomes are milky-white with 10 - 20 % turning amber, the plant is at peak THC. More amber trichomes indicate heavier, more sedative effects. Also look for pistils that have darkened and curled in (70 %+ brown pistils), and swollen calyxes.
What's the fastest way to grow cannabis?
The fastest path from seed to harvest is growing autoflowers in coco coir or hydroponics under 20/4 light. Many modern autoflower strains finish in 8 - 10 weeks. Hydroponic methods accelerate nutrient uptake, shaving days off each phase. Keeping temperatures at 75 - 80 °F with optimal VPD also speeds growth without sacrificing quality.
How many weeks does flowering take?
Flowering duration depends on genetics. Indica-dominant strains typically flower in 7 - 9 weeks. Hybrid strains take 8 - 10 weeks. Sativa-dominant strains can take 10 - 14 weeks. Autoflowers have a fixed flowering window built into their life cycle, usually 5 - 7 weeks of actual flower development within their total 8 - 12 week lifespan.
Can I speed up the vegetative stage?
Yes. Running lights at 20/4 or even 24/0 during veg accelerates growth compared to 18/6. Maintaining temperatures at 77 - 82 °F, keeping humidity at 60 - 70 %, and providing strong light (600 - 800 PPFD) maximizes vegetative growth rate. Hydroponic and coco setups grow faster than soil because roots access nutrients more efficiently.
When should I start training my cannabis plant?
Begin Low-Stress Training (LST) once the plant has 4 - 5 nodes, typically in week 3 of veg. Topping can be done at the 4th - 6th node. Avoid training autoflowers aggressively since they have a fixed timeline and cannot recover from heavy stress. For photoperiod plants, training throughout veg and into the first week of flower maximizes canopy evenness.
How long do autoflowers take from seed to harvest?
Most autoflowers take 8 to 12 weeks from germination to harvest. Fast autoflower varieties can finish in as little as 60 days, while larger autoflower strains may run 12 - 13 weeks. The entire lifecycle is predetermined by genetics, so there is no separate vegetative switch. Expect 3 - 4 weeks of vegetative growth followed by 5 - 8 weeks of flowering.
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