What is Daily Light Integral (DLI)?
DLI measures the total amount of photosynthetically active radiation (PAR) delivered to a plant over a 24-hour period, expressed in mol/m²/day. It's the most accurate way to assess whether plants receive enough light for optimal growth.
DLI = PPFD × 3600 × Hours / 1,000,000
DLI guidelines by crop
- 5–10 mol/m²/day: Low-light plants (lettuce, herbs, orchids)
- 10–20 mol/m²/day: Medium (most vegetables, flowers)
- 20–30 mol/m²/day: High (peppers, cannabis, tomatoes)
- 30+ mol/m²/day: Very high (full-sun field crops)