Short answer
Yes. Cannabis leaves commonly droop or lower in the dark period and lift again within an hour or two of lights-on. Worry only if they are still drooping 2 hours after lights-on, or droop in the day. Then lift the pot and check the watering and roots. Grower practice.
Why
Plants move their leaves on a daily rhythm. Many species lower or fold their leaves at night and raise them by day [1], and cannabis leaves often settle in the dark and rise after lights-on. The reasons are still debated [1]. In practice it is harmless.
A plant that droops by day is different. Overwatered roots run short of oxygen and the leaves droop thick and firm. Underwatered plants go limp and papery.
Some daytime wilting points to the roots. A plant that wilts in a moist pot of normal weight, especially one plant at a time, fits Pythium or Fusarium root rot [2] or Fusarium wilt [3].
The numbers
| Observation | Meaning |
|---|---|
| Leaves lower after lights-off, up by lights-on + 1–2 h | Normal |
| Still drooping 2 h after lights-on, heavy pot | Overwatered |
| Still drooping, very light pot | Underwatered; recovers 30–120 min after watering |
| Wilting in a normal-weight pot | Check the roots for rot [2] |
| Brown streaks inside a cut stem | Possible Fusarium wilt [3] |
What to do
- Look again 1–2 hours after lights-on. If the leaves have lifted, you're done.
- If not, lift the pot and compare it with one freshly watered.
- Heavy: let it dry back until it is about 40–50% lighter before watering.
- Light: water slowly in two passes to light runoff.
- Normal weight but still wilting: slide the plant out or pull the net pot and check that the roots are white and firm.
- In hydro, check the air pump and keep the solution at 18–22 °C (64–72 °F).
Common mistakes
- Watering at lights-off because the plant "looks thirsty".
- Opening the tent in the dark period to check on it.
- Treating every droop as thirst.
- Ignoring daytime drooping because "it does that at night".
Related
- Full article: Drooping cannabis: overwatering vs underwatering
- Answers: praying leaves · water at lights-on or off? · how often to water
- Article: root browning in hydro
- Terms: overwatering · underwatering
