# Can I grow autoflowers outdoors?

> Yes: autoflowers grow well outdoors because they flower by age, not day length, finishing about 9–14 weeks from seed. Sow straight into the final container or bed once nights stay above about 10 °C (50 °F). At mid-latitudes a late-spring sowing finishes in mid to late summer, and a second sowing by early summer can finish before autumn rain. Any setback costs yield: no transplanting, LST instead of topping.

- Canonical: https://genetixbay.com/knowledge/answers/autoflowers-outdoors.html
- Topic: Outdoor growing · Type: How-to
- Evidence: Grower practice · Status: Draft: awaiting expert review
- Full article: [Photoperiod vs autoflower, and how autoflowering is inherited](https://genetixbay.com/knowledge/basics/photoperiod-vs-autoflower.md)
- Also asked as: Growing autos outdoors | When to plant autoflowers outside | Can I get two autoflower harvests in one summer? | Autoflower outdoor season | Are autoflowers good for a short outdoor season?
- Updated: 2026-10-31 · Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay Knowledge Base (genetixbay.com/knowledge)"

## Short answer

Yes. [Autoflowers](https://genetixbay.com/knowledge/glossary/autoflower.md) flower by age, usually 3–5 weeks from [sprouting](https://genetixbay.com/knowledge/glossary/germination.md), and finish about 9–14 weeks from seed whatever the [day length](https://genetixbay.com/knowledge/glossary/photoperiod.md), so they suit outdoor gardens, short seasons and second crops. House position: any setback costs an auto yield, so sow straight into the final container or bed, and use [LST](https://genetixbay.com/knowledge/glossary/lst.md), not topping. *Grower practice*, house-endorsed.

## Why

Autos ignore the calendar. Autoflowering is controlled by a [recessive](https://genetixbay.com/knowledge/glossary/recessive.md) [locus](https://genetixbay.com/knowledge/glossary/locus.md), *Autoflower1*, so the plant flowers on its own clock rather than waiting for long nights [1].

Sun is a bonus. Yield rose in a straight line with light in a controlled trial [2], and long summer days give an auto far more daily light than it would get indoors.

Root setbacks cost time. Any [transplant shock](https://genetixbay.com/knowledge/glossary/transplanting.md) eats into a fixed countdown, and the founder finds the auto [taproot](https://genetixbay.com/knowledge/glossary/taproot.md) reacts badly to being moved. Bigger containers give bigger plants within reason [3], so choose the final size at sowing.

Timing dodges the weather. A summer finish avoids the cool, wet autumn that drives gray mould on dense buds [4].

## The numbers

| Item | Northern Hemisphere (mid-latitudes) | Southern Hemisphere |
|---|---|---|
| First sowing | After last frost, late May | Late November |
| First harvest | Mid–late August | Mid–late February |
| Latest second sowing | Early July | Early January |
| Second harvest | Late September–early October | Late March–early April |
| Seed to harvest | ~9–14 weeks | ~9–14 weeks |
| Container | 11–25 L (3–7 US gal), final from day one | Same |

## What to do

1. Check local rules on outdoor growing first.
2. Sow after the last frost, once nights stay above about 10 °C (50 °F).
3. Sow directly in the final container or prepared bed; no transplanting.
4. Protect [seedlings](https://genetixbay.com/knowledge/glossary/seedling.md) from slugs and wind for the first two weeks.
5. Tie the main stem down in weeks 2–4 for LST; never top.
6. Water and feed without gaps; a hungry or dry week costs yield.
7. For a second crop, sow by early July (early January in the south).

## Common mistakes

- Starting autos in cups and transplanting them outside.
- Topping an outdoor auto.
- Sowing the second crop too late, into autumn rain.
- Treating autos as easy: they punish stress.

## Related

- Full article: [Photoperiod vs autoflower, and how autoflowering is inherited](https://genetixbay.com/knowledge/basics/photoperiod-vs-autoflower.md)
- Answers: [How long autoflowers take](https://genetixbay.com/knowledge/answers/how-long-do-autoflowers-take.md) · [Plant straight into the final pot](https://genetixbay.com/knowledge/answers/plant-straight-into-final-pot.md) · [Short northern seasons](https://genetixbay.com/knowledge/answers/outdoor-short-season.md)
- Article: [Low-stress training](https://genetixbay.com/knowledge/training/lst.md)
- Terms: [autoflower](https://genetixbay.com/knowledge/glossary/autoflower.md)

## Follow-up questions

**Can I get two autoflower harvests outdoors in one season?** Yes, two outdoor autoflower harvests in one season are possible at mid-latitudes. Sow the first round after the last frost, in late May in the Northern Hemisphere or late November in the Southern, for a harvest about 9–14 weeks later. Sow the second round by early July (early January in the south) so it finishes before autumn rain and cold. This is grower practice.

**Should I top outdoor autoflowers?** No, don't top outdoor autoflowers. GenetixBay's house position is that topping never produces what proper low-stress training does on an auto, because the plant runs on a strict countdown and cannot pause to recover. Bend and tie the main stem down early in veg instead to open the canopy to the sun. The same rule applies indoors and out.

**What size container for outdoor autoflowers?** Outdoor autoflowers do well in about 11–25 litre (3–7 US gallon) containers, or sown direct in a prepared bed, and the container should be the final one from day one. Bigger pots give bigger plants within reason but dry more slowly, so match the pot to how often you can water. In hot sun, small pots can dry within a day, so check them daily.

## Sources

1. 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. https://doi.org/10.3389/fpls.2022.991680
2. 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. https://doi.org/10.3389/fpls.2021.646020
3. Poorter H, Bühler J, van Dusschoten D, Climent J, Postma JA. 2012. Pot size matters: a meta-analysis of the effects of rooting volume on plant growth. Functional Plant Biology 39(11):839-850. https://doi.org/10.1071/FP12049
4. PNW Plant Disease Management Handbook. Hemp (Cannabis sativa) - Gray Mold. https://pnwhandbooks.org/plantdisease/host-disease/hemp-cannabis-sativa-gray-mold-botrytis-bud-blight-stem-canker