# How long is the seedling stage?

> The cannabis seedling stage lasts about 2–3 weeks from emergence. It ends when the plant has 3–4 nodes of true leaves with full-sized, multi-fingered leaflets and roots filling a small pot; then it's in veg. At 150–300 µmol/m²/s, 18 hours a day and 23–27 °C (73–81 °F) it moves fastest. Cold, low light or overwatering can stretch it to 4 weeks or more.

- Canonical: https://genetixbay.com/knowledge/answers/how-long-is-the-seedling-stage.html
- Topic: Germination · Type: Numbers
- Evidence: Grower practice · Status: Draft: awaiting expert review
- Full article: [Seedling care: the first three weeks](https://genetixbay.com/knowledge/germination/seedling-care.md)
- Also asked as: How long are cannabis plants seedlings? | When does the seedling stage end? | When does a seedling become veg? | Why is my cannabis seedling so stretched?
- 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

The cannabis [seedling stage](https://genetixbay.com/knowledge/glossary/seedling.md) lasts about 2–3 weeks from emergence, ending at 3–4 nodes of [true leaves](https://genetixbay.com/knowledge/glossary/true-leaves.md) with multi-fingered [leaflets](https://genetixbay.com/knowledge/glossary/leaflet.md). Good light (150–300 [µmol/m²/s](https://genetixbay.com/knowledge/glossary/ppfd.md), 18 h) and warmth (23–27 °C / 73–81 °F) keep it short. *Grower practice*.

## Why

A seedling is limited by its tiny root and few leaves. Growth accelerates once true leaves are photosynthesising and roots have filled a small container.

Light sets the pace. Young plants given a [DLI](https://genetixbay.com/knowledge/glossary/dli.md) of about 10–14 mol/m²/day root and grow better than dimly lit ones in other crops [1], and cannabis responds to higher light in veg with compact, robust growth [2].

[Stretch](https://genetixbay.com/knowledge/glossary/stretch.md) is the sign of too little light. The stem elongates looking for it, giving a tall, weak seedling that can flop.

The end of the seedling stage is practical, not botanical: when roots fill the plug or cup it's time to [pot up](https://genetixbay.com/knowledge/glossary/up-potting.md) [3] and treat the plant as veg.

## The numbers

| Days from emergence | What you see | Light (µmol/m²/s) |
|---|---|---|
| 0–5 | [Cotyledons](https://genetixbay.com/knowledge/glossary/cotyledon.md) open | 100–200 |
| 5–10 | First true leaves (1–3 fingers) | 150–250 |
| 10–21 | Nodes 2–4, leaves with more fingers | 200–300+ |
| ~14–21 | Roots fill plug or cup; enter veg | 300+ as veg begins |

| Condition | Target |
|---|---|
| [Photoperiod](https://genetixbay.com/knowledge/glossary/photoperiod.md) | [18/6](https://genetixbay.com/knowledge/glossary/18-6.md) ([24/0](https://genetixbay.com/knowledge/glossary/24-0.md) also fine) |
| Air | 23–27 °C (73–81 °F), 65–75% [RH](https://genetixbay.com/knowledge/glossary/relative-humidity.md) |
| First feed | [EC](https://genetixbay.com/knowledge/glossary/ec.md) 0.4–0.8 [mS/cm](https://genetixbay.com/knowledge/glossary/ms-cm.md) at 2–3 true-leaf sets |

## What to do

1. Count nodes, not days.
2. Measure PPFD; raise it if the stem stretches.
3. Keep the medium just moist, never soggy.
4. Start a light feed at 2–3 sets of true leaves.
5. Pot up photoperiods when roots reach the edges; leave [autos](https://genetixbay.com/knowledge/glossary/autoflower.md) in their final pot.

## Common mistakes

- A weak light 1 m away, then wondering why it stretched.
- Calling it "veg" by the calendar while it still has two nodes.
- Holding a seedling in a tiny cup until it is [root-bound](https://genetixbay.com/knowledge/glossary/root-bound.md).

## Related

- Full article: [Seedling care: the first three weeks](https://genetixbay.com/knowledge/germination/seedling-care.md)
- [Stretching](https://genetixbay.com/knowledge/diagnosis/stretching.md) · [Life cycle](https://genetixbay.com/knowledge/basics/life-cycle.md)
- [Light schedule for seedlings](https://genetixbay.com/knowledge/answers/light-schedule-for-seedlings.md)
- Terms: [seedling](https://genetixbay.com/knowledge/glossary/seedling.md) · [stretch](https://genetixbay.com/knowledge/glossary/stretch.md)

## Follow-up questions

**Why is my cannabis seedling so stretched?** A cannabis seedling that grows a long, thin, pale stem is usually getting too little light, or the light is too far away. Raise intensity gradually toward 150–300 µmol/m²/s for 18 hours, and add gentle air movement to firm the stem. At transplant, bury the stretched stem deeper in soil or coco. A pinched, brown stem base is damping-off instead.

**When do seedlings get their first true leaves?** Cannabis seedlings usually show their first true leaves, often single-bladed or three-fingered, about 5–10 days after emerging. Each new node then brings leaves with more fingers, typically 5 by the third or fourth node. Seedlings that take much longer are usually cold, under-lit or overwatered rather than slow genetics.

**When should I transplant a seedling?** Transplant a cannabis seedling when roots reach the sides and bottom of its plug or cup but before they circle, typically 2–3 weeks from sprouting at about 2–4 true-leaf nodes. Water lightly the day before so the root ball holds together. Autoflowers are the exception: sow them straight into the final pot and don't transplant.

## Sources

1. Runkle E. The benefits of lighted plugs. Michigan State University Extension. https://www.canr.msu.edu/resources/the_benefits_of_lighted_plugs
2. Moher M, Llewellyn D, Jones M, Zheng Y, 2021. High light intensities can be used to grow healthy and robust cannabis plants during the vegetative stage of indoor production. Preprints (not peer reviewed). https://doi.org/10.20944/preprints202104.0417.v1
3. University of Minnesota Extension. Starting seeds indoors (transplanting seedlings, hardening). https://extension.umn.edu/planting-and-growing-guides/starting-seeds-indoors