Autoflower seeds are cannabis seeds that switch from vegetative growth to flowering on their own, about 2 to 4 weeks after sprouting, with no change in the light schedule. They carry the trait from Cannabis ruderalis, a day-neutral subspecies native to Central Asia and Siberia. You plant the seed, keep a steady light cycle, and harvest in about 8 to 12 weeks from germination.
Autoflower Seed Bank Recommendations: US Buyer Guide
How Do Autoflower Seeds Work?
Autoflowering comes from genes that trigger bloom based on plant age, not on the number of dark hours per day. Photoperiod cannabis needs long nights to start flowering, which is why indoor growers flip the timer to 12/12. Autoflowers skip that step and bloom under 18/6, 20/4, or even 24/0.
The trait traces to Cannabis ruderalis, a short, sturdy plant that evolved in regions with brief growing seasons. Breeders crossed ruderalis with Cannabis indica and Cannabis sativa to keep the automatic flowering while raising potency and yield.
autoflower seed bank recommendations
Autoflower vs Photoperiod Seeds: Key Differences
- Light cycle: autos flower under any schedule; photoperiod plants need 12 hours of dark to bloom.
- Timeline: autos finish in 8 to 12 weeks from seed; photoperiod plants take as long as you keep them in veg, plus 8 to 11 weeks of flower.
- Height: autos stay short, often 60 to 120 cm; photoperiod plants can be trained to fill a room.
- Yield per plant: photoperiod plants win; autos win on speed and turnover.
- Cloning: photoperiod plants clone well; an autoflower clone keeps the mother's age and stays small.
- Power use: autos run longer light hours, so daily electricity use is higher.
How Long Do Autoflowers Take From Seed to Harvest?
Most autoflowers finish in 8 to 12 weeks from germination. Fast indica-leaning strains can be ready in 7 weeks, while larger sativa-leaning plants may need 13 or 14 weeks. Breeders print a harvest window on each pack, and that window assumes good light, steady temperatures, and no major stress.
how long do autoflower seeds take to grow
- Week 1: seedling stage, root establishment.
- Weeks 2 to 4: vegetative stretch, then pre-flowers near week 3 or 4.
- Weeks 4 to 8: flowering, bud sites form and swell.
- Weeks 8 to 12: ripening, trichomes turn cloudy and amber.
Do Autoflower Seeds Yield Less Than Photoperiod Seeds?
Per plant, yes, in most cases. A compact autoflower in a 3-gallon pot under decent light gives about 1 to 3 ounces of dried flower. Modern large autos in a 5- to 7-gallon pot with strong light can hit 4 to 8 ounces.
Per square foot per year, autos can close the gap. Three autoflower harvests in a year beat one long photoperiod run when the veg time for the photo plant eats months of the calendar.
Are Autoflower Seeds Good for Beginners?
They are the least fussy option for a first grow. You never track light leaks, never flip a timer, and never worry about a plant outgrowing the tent.
- Start in the final pot. Transplant shock stalls an auto because the clock keeps running.
- Use a light schedule of 18/6 or 20/4. Both work.
- Feed lighter than you would a photoperiod plant of the same size.
- Skip heavy defoliation and high-stress training after week 3.
What THC Level Do Autoflowers Have?
Modern autoflower seeds from established breeders test between 15% and 25% THC, with some cultivars landing higher. Early auto lines from the 2000s sat near 10% or below because ruderalis carries little THC. Years of backcrossing changed that.
Autoflower seeds also come in high-CBD and balanced versions. CBD-rich autos often land between 5% and 15% CBD with low THC.
Common Mistakes With Autoflower Seeds
- Transplanting. Auto roots dislike disturbance; plant the germinated seed in its final container.
- Topping too late. Topping at week 2 can work. Topping at week 5 cuts yield.
- Overfeeding. Small plants with a fast metabolism burn from hot soil and heavy nutrient doses.
- Weak light. An auto cannot make up for low light with extra veg time, so a weak lamp means a small harvest.
- Harvesting early. Check trichomes with a loupe or macro lens instead of counting days on a calendar.
Frequently Asked Questions
Can you clone autoflower seeds?
You can root a cutting, but the clone keeps the mother's age. It flowers at the same time as the parent and stays small, so the yield is poor. Buy fresh seeds instead.
Do autoflowers need a 12/12 light schedule?
No. They flower under 18/6, 20/4, or 24/0. A 12/12 schedule works too, but the plants get less light and produce less.
Are autoflower seeds feminized?
Many are, but not all. Read the pack label. Feminized auto seeds produce female plants, while regular auto seeds give roughly half males.
Can you grow autoflowers outdoors?
Yes. Their short cycle suits northern summers with cool falls. They also fit a balcony or greenhouse, and automatic flowering means no light-deprivation tarp.
How much do autoflower seeds cost?
Prices run from about $8 to $20 per seed at licensed shops, and premium breeders charge more. Multi-seed packs bring the per-seed cost down.
Are autoflower seeds legal?
It depends on where you live. In the US, rules vary by state. Buy from licensed retailers, check your local law, and ask shop staff about current limits before you plant.