PPFD/DLI Guides
Learn about optimal light levels for cannabis cultivation. This guide covers Photosynthetic Photon Flux Density (PPFD) and Daily Light Integral (DLI) recommendations for each growth stage.
PPFD/DLI Guide
Recommended PPFD levels for different growth phases
100-300
Seedling/Clone
PPFD: 100-300 μmol/m²/s
Hours: 18-24h
Keep light further away from plants to reduce intensity
300-600
Vegetation
PPFD: 300-600 μmol/m²/s
Hours: 18h
Gradually increase PPFD as plants mature
600-800
Early Flowering
PPFD: 600-800 μmol/m²/s
Hours: 12h
Transition light schedule to 12/12 to trigger flowering
800-1000
Mid Flowering
PPFD: 800-1000 μmol/m²/s
Hours: 12h
Monitor for light stress and adjust as needed
1000-1200
Late Flowering
PPFD: 1000-1200 μmol/m²/s
Hours: 12h
Some strains may benefit from slightly reduced light in final week
Understanding PPFD
PPFD (Photosynthetic Photon Flux Density) measures the amount of photosynthetically active radiation (PAR) that reaches your plants, measured in micromoles per square meter per second (μmol/m²/s). Higher PPFD values indicate more intense light. The optimal PPFD varies depending on the growth stage of your cannabis plants.
Daily Light Integral (DLI)
Total amount of PAR received in a 24-hour period
| Growth Stage | Recommended DLI (mol/m²/day) | Notes |
|---|---|---|
| Seedling/Clone | 6-10 | Lower DLI prevents stress in young plants |
| Vegetation | 16-30 | Promotes healthy leaf and stem development |
| Early Flowering | 25-35 | Supports transition to flowering |
| Mid Flowering/Late Flowering | 35-45 | Maximizes bud development and resin production |
DLI = PPFD × (photoperiod in seconds) × 10⁻⁶
Example: 600 μmol/m²/s × (18 hours × 3600 seconds) × 10⁻⁶ = 38.9 mol/m²/day