Grow lights
Your own grow lights: type, wattage, height and schedule. Add a PPFD value and the app calculates the daily light integral (DLI).
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My lights
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Reference values
General guide values for herbs, vegetables and houseplants. Always check the needs of your own plant and the nutrient maker's instructions.
What is DLI?
DLI (daily light integral) is the amount of light a plant gets during a day. PPFD is the momentary light intensity at the canopy; DLI is how much light adds up over the whole day. Fruiting plants need much more light than leafy plants.
DLI (mol/m²/day) = PPFD (µmol/m²/s) × light hours × 3600 ÷ 1,000,000
Example: 250 µmol/m²/s × 16 h × 3600 ÷ 1,000,000 = 14.4 mol/m²/day.
Suggested DLI by plant
| Plant | DLI (mol/m²/day) |
|---|---|
| seedlings and cuttings | 5–10 |
| microgreens | 9–12 |
| parsley | 10–15 |
| lettuce | 12–17 |
| spinach | 14–20 |
| cilantro | 15–20 |
| basil | 15–25 |
| tomato, cucumber, zucchini | 20–30 |
Light hours and intensity
- Seedlings: 16–18 hours of light per day (UMN).
- Hydroponic lettuce and herbs: 12–14 h (UMN).
- Foliage houseplants: 12–14 h; flowering houseplants: 14–16 h (UMN).
- Medium light 150–250 and high light 250–450 µmol/m²/s (UMN).
Practical tips
- Use a timer – a steady rhythm matters more than one long day.
- Stretched, pale seedlings mean too little light (Purdue).
- For lettuce, more than 17 mol/m²/day can cause tipburn (VCE).
- For leafy greens, 1 % more light gives roughly 1 % more yield – up to a point (VCE).
- Lights heat the room: take care of ventilation and air circulation (VCE).
Sources
- Virginia Cooperative Extension – Calculating and Using Daily Light Integral (DLI), SPES-720
- University of Minnesota Extension – Lighting for indoor plants and starting seeds
- Purdue University Vegetable Crops Hotline – Managing Daily Light Integral to Improve Vegetable Transplant Quality
- Virginia Cooperative Extension – Hydroponic Production of Edible Crops: Management Basics, SPES-462
General home growing information – does not replace the instructions of your equipment or nutrient maker. Electricity and water: use a socket with a residual current device (RCD).