# Your first grow, start to finish: the master guide

> A first indoor grow takes about 3–5 months from seed to jar: 1 week to set up and test the room, 1–2 weeks of germination and seedling, 3–6 weeks of veg (photoperiods), a 10–14 day transition after the flip, 7–10 weeks of flower, 7–14 days of drying and at least 2–4 weeks of curing. Use one to four feminised plants, a tent, one good LED, a fan and carbon filter, 11–19 L pots, a pH pen and an EC meter, and keep a journal.

- Canonical: https://genetixbay.com/knowledge/guides/first-grow-start-to-finish.html
- Category: Start here · Level: Beginner
- Evidence: Supported · Status: Draft: awaiting expert review
- Stage: Any stage · Systems: Soil, Coco, DWC
- 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

**How long does a first cannabis grow take from seed to harvest?** A first indoor photoperiod grow takes about 14–20 weeks from seed to harvest: 1–2 weeks of [germination](https://genetixbay.com/knowledge/glossary/germination.md) and [seedling](https://genetixbay.com/knowledge/glossary/seedling.md), 3–6 weeks of veg, a 10–14 day transition after the [flip to 12/12](https://genetixbay.com/knowledge/glossary/12-12.md), then 7–10 weeks of flower. Add 1–2 weeks of drying and 2–4+ weeks of curing. A [feminised](https://genetixbay.com/knowledge/glossary/feminised-seed.md) [autoflower](https://genetixbay.com/knowledge/glossary/autoflower.md) is quicker, usually 9–14 weeks from seed to harvest, with no flip.

**What is the step-by-step order of a first grow?** The order of a first cannabis grow is: check the law, set up and test the room for 48 hours, germinate, raise seedlings under gentle light, veg (photoperiods only, 3–6 weeks), flip to 12/12 and allow a 10–14 day transition, flower for 7–10 weeks while feeding through to the end, harvest by [trichomes](https://genetixbay.com/knowledge/glossary/trichome.md), dry slowly for 7–14 days, then cure in jars for 2–8 weeks.

**How many plants should I grow the first time?** Grow one to four plants on a first run, within your local legal limit. In a 60 x 60 cm (2 x 2 ft) tent, one or two plants is plenty; in a 120 x 120 cm (4 x 4 ft) tent, two to four. Fewer plants means fewer pots to water and lift, more attention per plant and less damage from any one mistake.

**What is the biggest mistake on a first grow?** Overwatering is the biggest single mistake on a first cannabis grow, followed by overfeeding and fiddling. Water when the pot feels light, not on a schedule; feed below the label rate; change one thing at a time and wait three to five days to see the result on new growth. A dated journal turns those mistakes into lessons for the next run.

**Should I [flush](https://genetixbay.com/knowledge/glossary/flushing.md) my plants before harvest on a first grow?** No. Pre-harvest flushing is a myth, and it actively costs yield and resin: it starves the plant in its last weeks, when it is packing on most of its final weight and trichomes. Controlled studies found no quality gain. Keep feeding at stage strength through to harvest; if you mix single salts, taper only nitrogen late in flower. Taste comes from a healthy plant, a slow dry and a proper cure.

**How do I know when my first grow is ready to harvest?** Harvest when a 60x loupe shows the trichome heads on the buds (not the sugar leaves) as a mix: a few clear, mostly cloudy, some amber. That is a matter of taste: more cloudy for a brighter finish, more amber if you prefer it heavier. [Pistil](https://genetixbay.com/knowledge/glossary/pistil.md) colour and breeder week counts are only rough guides; count from the flip and add the 10–14 day transition.

**What equipment is essential for a first indoor grow?** The essential first-grow kit is a grow tent, one dimmable full-spectrum LED, an exhaust fan with a carbon filter, a small clip fan, 11–19 L (3–5 gal) fabric or plastic pots, quality potting mix or [coco](https://genetixbay.com/knowledge/glossary/coco-coir.md), a pH pen and [pH](https://genetixbay.com/knowledge/glossary/ph.md) up/down, an EC meter, a thermo-hygrometer, a timer, a 60x loupe and a journal. Everything else is optional on a first run.

**Short answer.** A first indoor grow takes about **3–5 months from seed to jar**. Set up and test the room for a week, germinate, run gentle light for 1–2 weeks of seedling, veg photoperiods for 3–6 weeks, flip to 12/12 and allow a **10–14 day transition** before flower really starts, flower for 7–10 weeks while feeding through to the end, then dry slowly for 7–14 days and cure for at least 2–4 weeks. Grow one to four feminised plants. Write everything down.

**Legal first.** Home growing is legal only in some places, with plant limits and rules about visibility and security. Do the [legal check before you grow](https://genetixbay.com/knowledge/guides/legal-check-before-you-grow.md) before you buy anything.

This guide is the spine of the "Start here" series. Each phase links to the step-by-step guide for it, and from there to the deep article with the evidence.

## What do you need for a first grow?

A first indoor grow needs a small set of generic equipment, nothing branded and nothing exotic. Buy for the space you have; see [choosing your setup](https://genetixbay.com/knowledge/guides/choosing-your-setup.md) for budget tiers.

- [ ] A grow [tent](https://genetixbay.com/knowledge/glossary/tent.md) sized to your space: 60 x 60 cm (2 x 2 ft) for one or two plants, 120 x 120 cm (4 x 4 ft) for two to four
- [ ] One dimmable full-spectrum [LED](https://genetixbay.com/knowledge/glossary/led.md) that can deliver about 600–900 [µmol/m²/s](https://genetixbay.com/knowledge/glossary/ppfd.md) over the tent footprint ([lights for beginners](https://genetixbay.com/knowledge/guides/lights-for-beginners.md))
- [ ] An inline [exhaust fan](https://genetixbay.com/knowledge/glossary/exhaust-fan.md) with a [carbon filter](https://genetixbay.com/knowledge/glossary/carbon-filter.md), plus one small clip or [oscillating fan](https://genetixbay.com/knowledge/glossary/oscillating-fan.md)
- [ ] 11–19 L (3–5 gal) pots, fabric or plastic with drainage, and saucers
- [ ] Quality bagged potting mix, or buffered coco plus perlite ([soil](https://genetixbay.com/knowledge/guides/soil-first-grow-week-by-week.md) or [coco](https://genetixbay.com/knowledge/guides/coco-first-grow-week-by-week.md))
- [ ] A [pH meter](https://genetixbay.com/knowledge/glossary/ph-meter.md) or pen, pH 4 and 7 calibration buffers, and pH up and down
- [ ] An [EC meter](https://genetixbay.com/knowledge/glossary/ec-meter.md) (needed for coco and hydro; very useful in soil)
- [ ] A thermo-hygrometer with min/max memory, ideally one that logs
- [ ] A mechanical or digital timer for the light
- [ ] A 60x [jeweller's loupe](https://genetixbay.com/knowledge/glossary/jewelers-loupe.md) or clip-on phone macro lens
- [ ] A base nutrient for your medium, a measuring syringe and a jug
- [ ] Soft plant ties or garden wire for training
- [ ] A [grow journal](https://genetixbay.com/knowledge/guides/grow-journal-101.md): paper, a spreadsheet or a GenetixBay journal
- [ ] Seeds of a well-documented feminised line ([reading a seed listing](https://genetixbay.com/knowledge/guides/reading-a-seed-listing.md))

## What does the whole grow look like, week by week?

The whole grow runs about 18–24 weeks for a photoperiod plant and 13–20 weeks for an autoflower, counting setup, drying and curing. The table is the timeline; treat the weeks as typical, not fixed, because cultivars differ.

| Week | Photoperiod plant | Autoflower plant | Light | Main job |
|---|---|---|---|---|
| 0 | Set up, run the room empty 48 h | Same | Test run | Log day and night temp and [RH](https://genetixbay.com/knowledge/glossary/relative-humidity.md); fix the climate first |
| 1 | Germinate, plant out | Germinate straight into the final pot | [18/6](https://genetixbay.com/knowledge/glossary/18-6.md), 150–300 µmol/m²/s | Keep the medium moist, not wet |
| 2–3 | Seedling | Seedling | 18/6, 200–400 | Tiny waterings; no feed in most bagged soils |
| 4–6 | Veg; pot up into the final pot | Early veg; start LST about week 3 | 18/6 (up to 24/0), 300–600 | Water by weight; start training |
| 7–8 | Late veg; flip at half the final height you can fit | Pre-flower and [stretch](https://genetixbay.com/knowledge/glossary/stretch.md) | Photo: 12/12 from the flip; auto: 18/6 or 20/4 | Fill the canopy evenly |
| 9–10 | **Transition: days 1–14 after the flip**, stretch | Flower | Photo 12/12, 600–900 | Count days since flip; check for [male flowers](https://genetixbay.com/knowledge/glossary/staminate-flower.md) |
| 11–16 | Flower (day 1 of flower is about day 10–14 after the flip) | Flower and ripening; most finish weeks 10–14 | 600–900 | Lower RH; weekly pest check; feed through |
| 17–19 | Ripening; harvest by trichomes | (Already in the jar) | Keep the dark period dark | No flush; taper only N if you mix salts |
| +1–2 | Dry 7–14 days | Dry 7–14 days | Dark room | 15–21 °C, 55–62 % RH |
| +2–8 | Cure in jars | Cure in jars | Dark | Slow moisture decline |

The flip is not day 1 of flower. In controlled studies the first real pistil clusters at the top of the plant appeared about 8–14 days after short days began, around 13–14 days on average across 27 hemp cultivars and up to three weeks in slow ones [2][3]. That's why runs go "longer" than a breeder's stated flowering time: see [the photoperiod grow calendar](https://genetixbay.com/knowledge/guides/photoperiod-grow-calendar.md) and [the flip-to-flower transition](https://genetixbay.com/knowledge/environment/flip-to-flower-transition.md).

## How do you run a first grow, step by step?

Run a first grow as twelve plain steps. Each step names its guide; follow that guide for the detail.

1. **Check the law.** Confirm home cultivation is legal where you live, the plant limit, and any rules on visibility, locks and smell. See [the legal check](https://genetixbay.com/knowledge/guides/legal-check-before-you-grow.md).
2. **Choose your space and kit.** Pick the tent size first, then size the light and fan to it. See [choosing your setup](https://genetixbay.com/knowledge/guides/choosing-your-setup.md) and [electrical and water safety](https://genetixbay.com/knowledge/guides/electrical-and-water-safety.md).
3. **Choose your plant type and medium.** For a first grow, a feminised photoperiod in soil is the most forgiving; an [autoflower](https://genetixbay.com/knowledge/guides/autoflower-first-grow-week-by-week.md) is faster but punishes setbacks. Compare [soil](https://genetixbay.com/knowledge/guides/soil-first-grow-week-by-week.md), [coco](https://genetixbay.com/knowledge/guides/coco-first-grow-week-by-week.md) and [DWC](https://genetixbay.com/knowledge/guides/dwc-first-grow-week-by-week.md).
4. **Run the empty room for 48 hours.** Log temperature and RH with lights on and off. Aim for 22–28 °C (72–82 °F) lights-on and no more than 6 °C (10 °F) cooler at night. See [climate basics](https://genetixbay.com/knowledge/guides/climate-basics-vpd-cheat-sheet.md).
5. **Germinate.** Keep seeds at 22–26 °C (72–79 °F), moist and dark; plant a cracked seed root-down 0.5–1 cm (¼–½ in) deep. See [germinating seeds](https://genetixbay.com/knowledge/guides/germinating-seeds-step-by-step.md).
6. **Raise the seedling (weeks 1–3).** Light at 150–300 µmol/m²/s for 18 h, RH 65–75 %, and only a small ring of water around the stem. Most seedling deaths are overwatering. See [watering](https://genetixbay.com/knowledge/guides/watering-how-much-how-often.md).
7. **Veg (photoperiods, 3–6 weeks).** Raise light to 300–600 µmol/m²/s, pot up into the final pot when roots fill the small one, start feeding lightly, and begin [training](https://genetixbay.com/knowledge/guides/training-basics.md): bend and tie, tuck rather than pluck.
8. **Flip to 12/12.** Do it when plants are about half the final height you can fit, because they commonly double in the stretch. Keep the dark period completely dark. Log the flip date. See [the grow calendar](https://genetixbay.com/knowledge/guides/photoperiod-grow-calendar.md).
9. **Watch the transition and confirm sex.** Days 1–14 after the flip are stretch and transition. Check every plant for male flowers or [herms](https://genetixbay.com/knowledge/guides/telling-sex-and-spotting-herms.md) and remove any that will shed pollen.
10. **Flower (7–10 weeks of flower).** Light at 600–900 µmol/m²/s, RH 45–55 % falling to 40–50 % late, and a [daily five-minute check](https://genetixbay.com/knowledge/guides/daily-five-minute-check.md). Feed at stage strength right to the end. Do not flush (see below).
11. **Harvest by trichomes.** Look at the heads on the buds with a 60x loupe and cut at a mix of a few clear, mostly cloudy, some amber. See [when to harvest](https://genetixbay.com/knowledge/guides/when-to-harvest.md).
12. **Dry, then cure.** Dry whole branches in the dark at 15–21 °C (60–70 °F) and 55–62 % RH for 7–14 days until small stems snap, then cure in jars, letting the buds' moisture fall slowly over 2–8 weeks. See [drying](https://genetixbay.com/knowledge/guides/drying-step-by-step.md) and [curing](https://genetixbay.com/knowledge/guides/curing-step-by-step.md).

## What numbers should a beginner aim for?

A beginner should aim for the middle of each range below and keep it steady; stability matters more than hitting an exact number. These are *Grower practice* ranges anchored to the cited studies; your cultivar may differ.

| Parameter | Seedling | Veg | Flower | Late flower |
|---|---|---|---|---|
| PPFD (µmol/m²/s) | 150–300 | 300–600 | 600–900 | 600–900 |
| Photoperiod | 18/6 | 18/6 to 24/0 | 12/12 or 13/11 (photos) | Same |
| Air temperature, lights on | 24–27 °C (75–81 °F) | 22–28 °C (72–82 °F) | 20–26 °C (68–79 °F) | 20–24 °C (68–75 °F) |
| RH | 65–75 % | 55–70 % | 45–55 % | 40–50 % |
| VPD (kPa, leaf) | 0.4–0.8 | 0.8–1.2 | 1.0–1.5 | 1.2–1.5 |
| pH, soil / coco and hydro | 6.2–6.8 / 5.8–6.2 | Same | Same | Same |
| Feed [EC](https://genetixbay.com/knowledge/glossary/ec.md) (mS/cm, coco) | 0.4–0.8 | 1.0–1.8 | 1.6–2.2 | 1.6–2.2 (taper N only) |

Yield rose roughly linearly with light up to about 1,800 µmol/m²/s in the best indoor trial [1], but a beginner gains more from steady, moderate light than from chasing the ceiling.

## Should you flush before harvest?

No. Pre-harvest flushing is a *Myth* in the GenetixBay evidence ladder, and a harmful one. Cutting off nutrients in the last 1–2 weeks starves the plant while it is packing on most of its final weight, trichomes and resin. Controlled trials found no improvement in quality from pre-harvest nutrient withdrawal [6][9]. Cannabis stores what it takes up in its tissue, and plain water at the end does not wash it out.

What to do instead: keep feeding at the strength the stage calls for until harvest. If you mix single salts, taper only nitrogen over the last few weeks while keeping P, K, Ca, Mg, S and the micronutrients fed; lower N can raise cannabinoid percentage while lowering total yield, a trade-off rather than a reason to flush [5]. The one valid flush is a [root-zone flush](https://genetixbay.com/knowledge/glossary/root-zone-flush.md) to clear salt build-up, at any stage. The full evidence is in [the flush debate](https://genetixbay.com/knowledge/harvest-cure/flush-debate.md) and [feeding basics](https://genetixbay.com/knowledge/guides/feeding-basics.md).

## How will you know it's working?

You'll know a first grow is working when the plant shows steady, even growth and your logs stay boring. Check these signs weekly:

- **Seedling:** the stem stays short and sturdy (not leaning or stretched), cotyledons stay green, and a new set of true leaves appears every 3–5 days.
- **Veg:** a new node every 2–4 days, leaves a mid to deep green held flat or slightly up, and the pot drying from heavy to light in 2–4 days.
- **Transition:** stretch of 50–150 % over 2–3 weeks, then white pistil clusters at the tips about 10–14 days after the flip.
- **Flower:** buds swell week on week, lower fan leaves yellow slowly in the last 2–3 weeks (normal), and the smell grows.
- **Ripening:** trichome heads turn from clear to mostly cloudy with some amber.
- **Dry:** small stems snap rather than bend after 7–14 days.
- **Logs:** temperature within about 3 °C (5 °F) of target and RH within about 5 points, day after day.

## What mistakes do beginners make on a first grow?

Beginners mostly fail from too much care, not too little. The common ones:

- **Watering on a schedule** instead of by pot weight. Drowned roots look like hunger, which tempts more feeding.
- **Feeding full label strength from week one.** Start at a quarter to half strength and work up by EC and plant response.
- **Lights too close or too strong** for a seedling, especially strong LEDs: bleached tops, upward-cupped leaves.
- **Counting the flip as day 1 of flower** and harvesting 10–14 days early.
- **Flushing for the last 1–2 weeks** "for taste". It costs yield and resin and gains nothing.
- **Harvesting by pistil colour** or by the calendar instead of by trichomes.
- **Drying fast and warm.** A hay smell from a rushed dry never cures out.
- **Transplanting an autoflower.** Plant autos straight into the final pot.
- **Changing three things at once** when something looks wrong. Change one, log it, wait 3–5 days and judge on new growth ([how to diagnose any problem](https://genetixbay.com/knowledge/diagnosis/how-to-diagnose-any-problem.md)).
- **Skipping the journal.** Without dates and readings, the next grow repeats this one's mistakes.

## Evidence

- Light and yield indoors: *Supported* by a cannabis-specific trial [1].
- The 10–14 day transition after the flip: *Supported* by controlled flowering studies [2][3]; the house position counts both days since flip and days of flower.
- Organic feed rates in coir veg: *Supported* [4].
- Nitrogen trade-off: *Supported* [5]. Pre-harvest flushing: *Myth* [6][9].
- Drying to aw 0.55–0.65: *Established* as a standard [7]; the drying climate is *Grower practice*.
- Mould and hygiene risks in humid flower rooms: *Established* [8].

## Sources

1. 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
2. Zhang M, Anderson SL, Brym ZT, Pearson BJ. 2021. Photoperiodic flowering response of essential oil, grain, and fiber hemp (Cannabis sativa L.) cultivars. Frontiers in Plant Science 12:694153. https://doi.org/10.3389/fpls.2021.694153
3. Spitzer-Rimon B, Duchin S, Bernstein N, Kamenetsky R. 2019. Architecture and florogenesis in female Cannabis sativa plants. Frontiers in Plant Science 10:350. https://doi.org/10.3389/fpls.2019.00350
4. Caplan D, Dixon M, Zheng Y. 2017. Optimal rate of organic fertilizer during the vegetative-stage for cannabis grown in two coir-based substrates. HortScience 52(9):1307-1312. https://doi.org/10.21273/HORTSCI12401-17
5. Saloner A, Bernstein N. 2021. Nitrogen supply affects cannabinoid and terpenoid profile in medical cannabis (Cannabis sativa L.). Industrial Crops and Products 167:113516. https://doi.org/10.1016/j.indcrop.2021.113516
6. Stemeroff J. 2017. Irrigation management strategies for medical cannabis in controlled environments. MSc thesis, University of Guelph. http://hdl.handle.net/10214/12125
7. ASTM D8197. Standard Specification for Maintaining Acceptable Water Activity (aw) Range (0.55 to 0.65) for Dry Cannabis Flower. ASTM International. https://store.astm.org/d8197-22.html
8. Punja ZK. 2021. Emerging diseases of Cannabis sativa and sustainable management. Pest Management Science 77:3857-3870. https://pmc.ncbi.nlm.nih.gov/articles/PMC8451794/
9. 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