How long do autoflowers take from seed to harvest?

Q: How long do autoflowers take from seed to harvest?

Autoflowers usually take about 9–14 weeks from sprouting to harvest, with fast lines near week 9–10 and long lines near week 13–14. They start flowering at about 3–5 weeks old whatever the light schedule. Add 1–2 weeks of drying before the buds are smokeable. Any setback, such as overwatering, transplanting or hunger, costs time the plant can't recover.

Short answer

Autoflowers take about 9–14 weeks from sprouting to harvest. Fast lines finish near week 9–10, long lines near week 13–14, and the light schedule doesn't change that. Add 7–14 days of drying. Grower practice for the durations; the age-based flowering behind them is Supported genetics.

Why

An autoflower is day-neutral. It carries two copies of a recessive allele at a mapped locus, Autoflower1, so it flowers by age rather than by night length ^[1]. Gene dosage at that locus shifts flowering time and height, which is part of why lines differ by weeks ^[2].

The clock starts at germination and doesn't stop. A photoperiod plant can stay in veg until it recovers from a mistake. An auto flowers on schedule whether it has recovered or not, so a setback costs size, and often a few days on the finish, never a longer harvest window you can use. That's the GenetixBay house position: any setback costs an auto.

More light means more growth in the same time, not an earlier finish. Yield rose with light in a controlled trial ^[3]; autos on 18–20 h get 1.5–1.7× the daily light of 12 h at the same intensity.

The numbers

Week from sprouting	What's happening
1–2	Seedling, first true leaves
3–4	Fast veg; preflowers appear
3–5	Pistils at the main tip: flowering starts
5–7	Stretch, early flower
8–10	Bulking
9–14	Ripening and harvest, by trichomes
+1–2	Drying

What to do

Plan the space for 14 weeks, and be pleased if it's 10.
Sow straight into the final pot; don't transplant.
Run one schedule throughout: 18/6, 20/4 or 24/0.
From about week 8, check trichomes every 2–3 days.
Harvest at a few clear, mostly cloudy, some amber heads.

Common mistakes

Harvesting on the breeder's week count instead of the trichomes.
Switching an auto to 12/12 "to speed it up". It doesn't; it only cuts light.
Starting in a cup and transplanting, which stalls the plant while the clock runs.
Assuming every seed in an auto pack is a true auto. Poorly stabilised lines throw photoperiods.

Full article: Photoperiod vs autoflower
Guide: Autoflower first grow, week by week
Answers: when autos start flowering · why my auto is small · checking trichomes
Terms: autoflower

A day-neutral cannabis plant that starts flowering by age, usually a few weeks after germination, regardless of light schedule; the trait is mainly recessive.Germination is the stage where a viable seed absorbs water, splits its shell and pushes out a root (radicle), usually within 1-7 days at 20-30 °C.A recessive allele only shows its effect when a plant carries two copies of it; in a single copy it is masked by a dominant allele and carried silently.A locus is the fixed position on a chromosome where a particular gene or DNA marker sits; the plural is loci.A gene is a stretch of DNA that carries the instructions for one functional product, usually a protein such as an enzyme, and is the basic unit of inheritance.The daily length of light versus dark; photoperiod cannabis flowers when nights grow long enough, rather than at a fixed age.The span of days, often one to two weeks, in which a cannabis plant is ripe enough to cut, judged mainly by trichome head colour and bud development.The first leaves produced by the shoot tip after the cotyledons, with the plant's characteristic serrated leaflets.The first individual flowers that form at stem nodes during late vegetative growth, letting a grower tell male from female before full flowering.The female reproductive organ of a flower (ovary, style and stigmas); in cannabis growers loosely call the visible white stigmas "pistils".The stretch is the rapid increase in height in the first two to three weeks after switching to flower, when many cultivars grow 1.5 to 3 times taller.A hair-like outgrowth of the plant's skin; in cannabis the glandular types make and store the resin holding cannabinoids and terpenes.Transplanting moves a plant and its root ball into a new container or the ground; done gently it causes little shock, but GenetixBay advises against it for autoflowers.18/6 is the standard vegetative light schedule: 18 hours of light and 6 hours of darkness each day, keeping photoperiod cannabis from flowering.12/12 is the classic flowering schedule for photoperiod cannabis: 12 hours of light and 12 hours of uninterrupted darkness, which triggers and sustains flowering.An IBL (inbred line) is a seed line that has been inbred and selected over many generations until it breeds true for its main traits, giving uniform offspring.

Follow-up questions

Do autoflowers finish faster on 24 hours of light?

No, autoflowers do not finish faster on more hours of light. They flower by age, so 18/6, 20/4 or 24/0 give roughly the same 9–14 week timeline. Longer days add daily light: at the same intensity, 18–20 hours gives about 1.5–1.7 times the light of 12 hours, which means more growth in the same number of days, not an earlier harvest.

Why is my auto taking longer than the breeder says?

An autoflower usually runs past the breeder's stated time because of genetics, setbacks or optimistic marketing. Stress early in the grow slows growth without stopping the flowering clock, and some 'autos' are poorly stabilised lines. Breeder times are claims, so plan for 9–14 weeks and decide the harvest day by trichomes, not the calendar.

How long does it take to grow an autoflower start to finish?

An autoflower takes about 9–14 weeks from seed to harvest, then roughly 7–14 days of drying and at least two weeks of curing for good flavour. Allow about 3–4 months from planting to a cured jar. A photoperiod plant grown indoors from seed usually takes about 3–5 months before drying.

Sources

Toth JA, Stack GM, Carlson CH, Smart LB. 2022. Identification and mapping of major-effect flowering time loci Autoflower1 and Early1 in Cannabis sativa L. Frontiers in Plant Science 13:991680. doi.org/10.3389/fpls.2022.991680

Kurtz LE, Brand MH, Lubell-Brand JD. 2023. Gene dosage at the autoflowering locus effects flowering timing and plant height in triploid cannabis. Journal of the American Society for Horticultural Science 148(2):83-88. doi.org/10.21273/JASHS05293-23

Rodriguez-Morrison V, Llewellyn D, Zheng Y. 2021. Cannabis yield, potency, and leaf photosynthesis respond differently to increasing light levels in an indoor environment. Frontiers in Plant Science 12:646020. doi.org/10.3389/fpls.2021.646020