Short answer
Cannabis clones wilt because they have no roots to replace water lost through their leaves. A little droop on days 1–2 is normal. Lasting wilt means humidity too low (aim 75–90% RH), light or heat too strong, or a rotting stem in a soggy plug. Grower practice.
Why
An unrooted cutting can only drink through its cut stem. Every leaf keeps transpiring, so dry air pulls it flat.
Light adds to the load. Horticultural guidance keeps cuttings at a low maximum, around 100–150 µmol/m²/s, at sticking [1]. Strong light on rootless leaves dries them faster than they can drink.
Humidity is the brake. In a hemp trial run at only about 64% RH, flats wilted at times, so the researchers resaturated the media and removed lower leaves to keep cuttings turgid [2]. Under a dome at 75–90% RH, that pressure mostly disappears.
Waterlogging kills from below. A soggy plug suffocates the stem base and invites Pythium and Fusarium, which also infect cannabis roots [3].
The numbers
| Symptom | Likely cause | Fix |
|---|---|---|
| Flat on day 1–2, recovers | Normal | Nothing |
| Flat past day 3, dry air | RH too low | Dome, 75–90% RH |
| Crisp edges, wilts at midday | Light or heat too high | 50–150 µmol/m²/s, 22–26 °C |
| Soft brown stem base | Rot in a soggy plug | Drier plugs; re-cut healthy tops |
| Lower leaves yellow after a week | Using reserves | Normal; feed once rooted |
| Wilts after dome removal | Hardening off too fast | Lid back on; slow down |
What to do
- Check the dome: RH 75–90%, vented once a day.
- Lower or dim the light to 50–150 µmol/m²/s.
- Squeeze a plug. If water runs out, stop watering.
- Check medium temperature: 22–26 °C (72–79 °F).
- Remove only cuttings with rotten stems.
Common mistakes
- Clones under a full-power veg light.
- No dome in a dry room.
- Watering plugs daily "because they're wilting".
- Pulling the dome off in one go.
Related
- Full article: Clone-only cuts and how to preserve them
- Humidity and light for clones · How long do clones take to root?
- Terms: cloning dome · hardening off
