How Much Light Does Leafy greens (lettuce, herbs) Need? PPFD & DLI
Short cycle with low light requirements and cool temperatures.
- Peak PPFD: 250–450 µmol/m²/s
- Peak DLI: 12–17 mol/m²/d
- Air temperature: 16–22 °C
- Relative humidity: 50–70 %
- VPD target: 0.7–1 kPa
- Do not leave the substrate dry for more than 2 days
Targets per growth stage
| Stage | From day | PPFD | DLI | Photoperiod | pH | EC |
|---|---|---|---|---|---|---|
| Seedling | 0 | 100–200 µmol/m²/s | 6–12 mol/m²/d | 16 h | 5.5–6 | 0.6–0.8 |
| Growth | 10 | 200–400 µmol/m²/s | 10–15 mol/m²/d | 16 h | 5.5–6 | 0.8–1.2 |
| Mature | 35 | 250–450 µmol/m²/s | 12–17 mol/m²/d | 16 h | 5.5–6 | 1.2–1.4 |
Watering
Avoid drying out completely; keep soil consistently slightly moist.