# Autoflower first grow, week by week

> A feminised autoflower runs about 9–14 weeks from seed to harvest on a fixed countdown from germination, so plant it straight into its final 11–19 L (3–5 gal) pot on day 1, never transplant, run 18/6 to 20/4 (24/0 also works) for the whole grow, and train with low-stress bending, not topping. Any setback costs time the plant can't get back.

- Canonical: https://genetixbay.com/knowledge/guides/autoflower-first-grow-week-by-week.html
- Category: Start here · Level: Beginner
- Evidence: Supported · Status: Draft: awaiting expert review
- Stage: Seedling, Veg, Flower, Harvest · Systems: Soil, Coco
- 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)"

## Questions and answers

**Should I plant an [autoflower](https://genetixbay.com/knowledge/glossary/autoflower.md) straight into its final pot?** Yes. Plant an autoflower seed straight into its final 11–19 L (3–5 gal) pot on day 1. Autos run on a fixed countdown from germination, and the GenetixBay house position is that [transplanting](https://genetixbay.com/knowledge/glossary/transplanting.md) is almost a no-no: the [taproot](https://genetixbay.com/knowledge/glossary/taproot.md) reacts badly to disturbance, growth stalls for days, and an auto has no veg time to recover. Start in a small wet ring of mix around the seed and water outwards as the roots grow.

**Can I top an autoflower?** You can, but the GenetixBay position is that topping an autoflower never produces what proper [low-stress training](https://genetixbay.com/knowledge/glossary/lst.md) does. Topping costs an auto several days of recovery on a clock it can't stop, and a late top can stunt it. Bend and tie the main stem from about day 14–21 instead, keep the canopy flat, and tuck leaves rather than pluck them. LST gives the same multi-cola shape without the setback.

**What light schedule is best for autoflowers?** Autoflowers flower by age, not night length, so run one schedule from seed to harvest: [18/6](https://genetixbay.com/knowledge/glossary/18-6.md) or 20/4 is standard, and [24/0](https://genetixbay.com/knowledge/glossary/24-0.md) also works because cannabis doesn't need a sleep period. Keep [PPFD](https://genetixbay.com/knowledge/glossary/ppfd.md) around 200–300 µmol/m²/s for seedlings, 400–600 in early veg and 600–900 in flower. Never switch an auto to 12/12; it only shortens the day and costs yield.

**How long does an autoflower take from seed to harvest?** Most feminised autoflowers take about 9–14 weeks from germination to harvest: roughly 2 weeks of seedling, 2–3 weeks of fast veg, pre-flowers around weeks 3–5 and 6–9 weeks of flowering. Breeder times are averages; your plant is ready when [trichome heads](https://genetixbay.com/knowledge/glossary/trichome-heads.md) show a few clear, mostly cloudy and some amber. Add 7–14 days of drying and at least 2–4 weeks of curing.

**Are autoflowers good for beginners?** Autoflowers suit beginners in that they are fast, stay small and need no light-schedule change, but they are not easy. Any stress, overwatering, transplant shock or late training cuts yield, because the plant can't extend its veg to recover. An auto shows quickly who has a green thumb. Grow one with simple, steady conditions: final pot from day 1, light feeding, LST only and one change at a time.

**When should I start training an autoflower?** Start low-stress training on an autoflower at about day 14–21, once it has 3–4 nodes and the stem is flexible. Bend the main stem over gently and tie it so the side shoots rise to the same height, then adjust ties every 2–3 days. Finish the main bending by about day 35, as flowers start stretching, because hard bending once stems stiffen risks snapping and stress.

**How much should I feed an autoflower?** Feed autoflowers lighter than [photoperiods](https://genetixbay.com/knowledge/glossary/photoperiod.md): plain water or a feed at about [EC](https://genetixbay.com/knowledge/glossary/ec.md) 0.4–0.6 mS/cm for the first 2 weeks, 0.8–1.2 in weeks 3–4, and 1.2–1.8 in flower, starting at a quarter to half the label rate. In quality bagged soil, often water only for the first 2–3 weeks. Feed through to harvest; don't flush. Watch leaf tips: dark, burnt tips mean too strong.

**Short answer.** A feminised [autoflower](https://genetixbay.com/knowledge/glossary/autoflower.md) runs about **9–14 weeks from seed to harvest** on a fixed countdown that starts at germination. Plant it **straight into its final 11–19 L (3–5 gal) pot on day 1**, never transplant, run **18/6 to 20/4** (24/0 also works) for the whole grow, and train with [low-stress training](https://genetixbay.com/knowledge/guides/training-basics.md), not topping. Every setback costs days the plant can't get back.

> **House position: autos are a countdown.** An autoflower flowers by age, not by night length, so any stress (a transplant, a drowned root zone, a heavy top) eats into a schedule it cannot extend. The founder's rulings: plant in the final pot (transplanting is almost a no-no, because of how the [taproot](https://genetixbay.com/knowledge/glossary/taproot.md) reacts), and topping will never produce what proper LST does. "Good for beginners" is true, but not because autos are easy. They show who has a green thumb.

This guide is the auto track of the [first grow master guide](https://genetixbay.com/knowledge/guides/first-grow-start-to-finish.md). The genetics behind "flowers by age" are in [photoperiod vs autoflower](https://genetixbay.com/knowledge/basics/photoperiod-vs-autoflower.md).

## What do you need for an autoflower grow?

An autoflower grow needs the same basic kit as any first grow, minus the second light schedule and the small starter pots. Check the [legal check](https://genetixbay.com/knowledge/guides/legal-check-before-you-grow.md) first.

- [ ] A [tent](https://genetixbay.com/knowledge/glossary/tent.md): 60 x 60 cm (2 x 2 ft) for 1–2 autos, 80 x 80 cm (2.7 x 2.7 ft) for 2–3, 120 x 120 cm (4 x 4 ft) for 4–6
- [ ] One dimmable full-spectrum [LED](https://genetixbay.com/knowledge/glossary/led.md) able to reach 600–900 µmol/m²/s over the footprint ([lights for beginners](https://genetixbay.com/knowledge/guides/lights-for-beginners.md))
- [ ] An exhaust fan with a [carbon filter](https://genetixbay.com/knowledge/glossary/carbon-filter.md), and a small clip fan
- [ ] One final pot per plant: 11–19 L (3–5 gal) [fabric pot](https://genetixbay.com/knowledge/glossary/fabric-pot.md) or plastic pot with drainage holes, plus saucers
- [ ] Light, airy medium: quality bagged potting mix with 20–30 % added [perlite](https://genetixbay.com/knowledge/glossary/perlite.md), or buffered [coco](https://genetixbay.com/knowledge/glossary/coco-coir.md) with 30 % perlite
- [ ] A timer, a [pH meter](https://genetixbay.com/knowledge/glossary/ph-meter.md) with [pH](https://genetixbay.com/knowledge/glossary/ph.md) 4 and 7 buffers, and an [EC meter](https://genetixbay.com/knowledge/glossary/ec-meter.md)
- [ ] A thermo-hygrometer with min/max memory
- [ ] Soft [plant ties](https://genetixbay.com/knowledge/glossary/plant-ties.md) or plastic-coated wire, and a few low hooks or pot-rim clips to tie to
- [ ] A 60x loupe, a measuring syringe, a watering jug and a [grow journal](https://genetixbay.com/knowledge/guides/grow-journal-101.md)
- [ ] Feminised autoflower seeds from a line with real journals ([reading a seed listing](https://genetixbay.com/knowledge/guides/reading-a-seed-listing.md))

## What does an autoflower grow look like, week by week?

An autoflower grow follows age, so the weeks below count from the day the seed cracked. Fast lines finish near week 9–10; long lines near week 13–14. The light schedule never changes.

| Week from germination | Stage | PPFD (µmol/m²/s) | Watering | Feed EC ([coco](https://genetixbay.com/knowledge/glossary/coco-coir.md); soil often water only) | Your job |
|---|---|---|---|---|---|
| 1 | Sprout, cotyledons | 150–250 | 50–100 mL ring around the stem every 1–2 days | 0–0.4 mS/cm | Keep warm 24–27 °C (75–81 °F), 65–75 % [RH](https://genetixbay.com/knowledge/glossary/relative-humidity.md) |
| 2 | First 2–3 true-leaf sets | 200–300 | 100–250 mL, widening the wet ring | 0.4–0.6 | Don't overwater; no training yet |
| 3 | Fast veg, 3–5 nodes | 300–450 | 0.3–0.7 L when the pot feels light | 0.6–1.0 | Start LST (day 14–21) |
| 4 | Fast veg, pre-flowers appear | 400–600 | 0.5–1.5 L | 0.8–1.2 | Adjust ties every 2–3 days |
| 5 | [Stretch](https://genetixbay.com/knowledge/glossary/stretch.md) begins, pistils at the top | 500–700 | 1–2 L | 1.0–1.4 | Finish main bends by about day 35 |
| 6–7 | Early flower, stretch | 600–900 | 1.5–3 L, 10–20 % runoff in coco | 1.2–1.6 | Tuck leaves; lower RH to 50–55 % |
| 8–10 | Mid flower, bulking | 600–900 | 2–3 L | 1.4–1.8 | Daily check; pest check weekly |
| 10–14 | Ripening | 600–900 | As needed | 1.4–1.8; taper N only if mixing salts | Watch trichomes; 40–50 % RH |

Water volumes assume an 11–15 L (3–4 gal) pot; scale up for 19 L (5 gal). See [watering](https://genetixbay.com/knowledge/guides/watering-how-much-how-often.md) for the pot-lift method.

## How do you grow an autoflower, step by step?

Grow an autoflower in eleven steps, and protect the countdown at every one of them.

1. **Set up and test the room for 48 hours.** Run the light on its final schedule (18/6 or 20/4) and log temperature and RH day and night. Aim for 22–28 °C (72–82 °F) lights on.
2. **Fill the final pot.** Fill an 11–19 L (3–5 gal) pot with light mix. Water the whole pot once to about 10 % runoff, then let it drain for a day so it's moist, not wet.
3. **Plant the seed in the final pot.** Make a hole 0.5–1 cm (¼–½ in) deep in the centre. Plant either a dry seed directly or a seed whose root has just cracked (root down). See [germinating seeds](https://genetixbay.com/knowledge/guides/germinating-seeds-step-by-step.md).
4. **Water only a small ring for the first 10–14 days.** Give 50–100 mL around the stem every 1–2 days so the top few centimetres stay moist while the rest of the pot dries. This pulls the taproot down instead of drowning it.
5. **Light gently, then raise it.** Start at 150–250 µmol/m²/s and step up about 50–100 µmol/m²/s every 3–4 days if leaves stay flat and green. See [lights for beginners](https://genetixbay.com/knowledge/guides/lights-for-beginners.md).
6. **Start feeding lightly at week 2–3.** In coco, feed every watering from the first true leaves at EC 0.4–0.6 mS/cm. In quality bagged soil, often water only until week 3. Start at a quarter to half the label rate. See [feeding basics](https://genetixbay.com/knowledge/guides/feeding-basics.md).
7. **Start LST at day 14–21.** When the plant has 3–4 nodes, bend the main stem gently towards the pot rim and tie it. Side shoots will turn upward; tie them out so all tips sit at the same height. See [training basics](https://genetixbay.com/knowledge/guides/training-basics.md) and [LST](https://genetixbay.com/knowledge/training/lst.md).
8. **Keep training through week 5, then stop bending hard.** Adjust ties every 2–3 days. Once stems stiffen in the stretch (about day 35–45), only tuck leaves aside to expose bud sites. Tuck, don't pluck.
9. **Lower humidity as buds form.** Move from 55–70 % RH in veg to 45–55 % in flower and 40–50 % in the last 2–3 weeks. See [climate basics](https://genetixbay.com/knowledge/guides/climate-basics-vpd-cheat-sheet.md).
10. **Feed through to harvest.** Keep feeding at stage strength until the chop. Don't flush: it starves the plant while it packs on its final weight and resin (see [the flush debate](https://genetixbay.com/knowledge/harvest-cure/flush-debate.md)).
11. **Harvest by trichomes.** From about week 9, check trichome heads on the buds with a 60x loupe every 2–3 days. Cut at a few clear, mostly cloudy, some amber. See [when to harvest](https://genetixbay.com/knowledge/guides/when-to-harvest.md), then [drying](https://genetixbay.com/knowledge/guides/drying-step-by-step.md) and [curing](https://genetixbay.com/knowledge/guides/curing-step-by-step.md).

## Why shouldn't you transplant or top an autoflower?

Don't transplant or top an autoflower because both cost recovery days on a clock that keeps running. A photoperiod plant can stay in veg until it recovers; an auto starts flowering at its age whether it has recovered or not.

**Transplanting.** The GenetixBay house position is that transplanting autos is almost a no-no. The founder's observation, compared with photoperiods, is that the auto taproot reacts badly to disturbance and growth stalls. Root volume matters too: across 65 studies, doubling pot size raised plant biomass by about 43 % on average [4], so a stunted root system in a small cup is a real loss. Extension guidance treats transplant shock as a normal setback for any seedling [6]; an auto simply has no time to absorb it. See [transplanting](https://genetixbay.com/knowledge/germination/transplanting.md).

**Topping.** Topping removes the main tip and makes the plant spend 5–10 days rebuilding two new leaders ([topping](https://genetixbay.com/knowledge/training/topping.md)). On an auto that time comes straight out of veg. LST gets the same flat, multi-cola canopy without cutting anything; in a controlled study on large photoperiod plants, opening up the canopy improved chemical uniformity between top and lower buds [5]. The house view: topping never produces what proper LST does on an auto.

## What light schedule should an autoflower run?

An autoflower should run one schedule from seed to harvest: **18/6 or 20/4**, and **24/0** also works. Autoflowering is day-neutral, inherited as a recessive [gene](https://genetixbay.com/knowledge/glossary/gene.md) (*Autoflower1*), so these plants flower by age even under long days [1][2]. More hours means more daily light, and yield rose with light in the best indoor trial [3].

| Schedule | [DLI](https://genetixbay.com/knowledge/glossary/dli.md) at 600 µmol/m²/s | Notes |
|---|---|---|
| 18/6 | 38.9 mol/m²/day | Standard; cooler, cheaper |
| 20/4 | 43.2 mol/m²/day | Common auto choice |
| 24/0 | 51.8 mol/m²/day | Endorsed; cannabis needs no sleep period in veg. Watch heat |
| 12/12 | 25.9 mol/m²/day | Don't: it only cuts light and yield |

DLI = PPFD x hours x 0.0036. Keep the flower DLI near 35–45 mol/m²/day for a beginner; more needs CO₂ and experience. See [PPFD and DLI by stage](https://genetixbay.com/knowledge/environment/ppfd-dli-by-stage.md).

## How will you know it's working?

You'll know an autoflower grow is working when it hits its age milestones without pauses. Compare your journal with these marks:

- **Day 3–7:** cotyledons open, stem short and upright, not stretched.
- **Day 10–14:** two to three sets of true leaves, deep green, held flat.
- **Day 14–28:** a new node every 2–3 days; the pot goes from heavy to light in 1–3 days.
- **Day 21–35:** white pistils at the main tip and branch tips (the auto's own "flip").
- **Weeks 5–7:** stretch of 50–100 %; tied shoots all reach the same height.
- **Weeks 7–10:** buds swell week on week; smell increases.
- **Final 2–3 weeks:** lower fan leaves fade slowly (normal); trichome heads turn mostly cloudy.

A plant that "sits" for 4–7 days with no new growth has had a setback: find the cause in your log before it happens again.

## What mistakes do beginners make with autoflowers?

Beginners lose most auto yield to stress early in the grow, when the plant is building the frame it will flower on.

- **Starting in a solo cup and transplanting.** Plant in the final pot from day 1.
- **Flooding the whole pot in week 1.** A seedling in 15 L of wet mix sits in airless soil. Water a small ring and widen it.
- **Topping, or topping late.** Train with LST instead.
- **Hard bending after day 40.** Stems stiffen in the stretch; bend gently or just tuck leaves.
- **Overfeeding.** Autos are usually smaller; start at a quarter to half label strength and judge by leaf tips.
- **Switching to 12/12 "to help it flower".** An auto doesn't need it and loses light.
- **Pots that are too small.** Below about 11 L (3 gal), you need very frequent watering and feeding to keep up; pot size is a trade-off against feeding frequency.
- **Harvesting by the breeder's week count** instead of by trichomes.
- **Flushing in the last two weeks.** It costs yield and resin and gains nothing [7].
- **Changing several things at once** when something looks off. One change, logged, then wait 3–5 days.

## Evidence

- Autoflowering as a single recessive locus (*Autoflower1*): *Supported* by genetic mapping [1] and gene-dosage work [2].
- Yield rising with light: *Supported* [3]. Longer photoperiods for autos are *Grower practice*; 24/0 is house-endorsed.
- Bigger root volume, bigger plants: *Established* across crops [4]; the auto taproot response to transplanting is the founder's observation (*Grower practice*, house position).
- Canopy shape and uniformity: *Supported* [5]. LST over topping for autos: *Grower practice*, house position.
- Pre-harvest flushing: *Myth* [7].

## 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. 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. https://doi.org/10.21273/JASHS05293-23
3. 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
4. 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
5. Danziger N, Bernstein N. 2021. Shape matters: plant architecture affects chemical uniformity in large-size medical cannabis plants. Plants 10(9):1834. https://pmc.ncbi.nlm.nih.gov/articles/PMC8468686/
6. University of Minnesota Extension. Starting seeds indoors (transplanting seedlings, hardening). https://extension.umn.edu/planting-and-growing-guides/starting-seeds-indoors
7. Alden MJ, Faust JE. 2025. Exploring the legacy practice of flushing in controlled-environment production of high-CBD cannabis. HortScience 60(10):1818-1825. https://doi.org/10.21273/HORTSCI18752-25