The formula
PPFD = DLI ÷ (hours × 0.0036)
Look for this PPFD value on your grow light’s chart. If the light only reaches it very close to the plant, run it longer (up to 16 hours) or choose a stronger light.
PPFD needed by plant
| Plant | DLI target | PPFD for 12 h | PPFD for 14 h | PPFD for 16 h |
|---|---|---|---|---|
| Low-light houseplants | 3–6 | 69–139 | 60–119 | 52–104 |
| Medium-light houseplants | 6–10 | 139–231 | 119–198 | 104–174 |
| African violets and moth orchids | 6–10 | 139–231 | 119–198 | 104–174 |
| Microgreens | 9–12 | 208–278 | 179–238 | 156–208 |
| Vegetable and flower seedlings | 10–12 | 231–278 | 198–238 | 174–208 |
| Succulents and cacti | 12–16 | 278–370 | 238–317 | 208–278 |
| Herbs and leafy greens | 12–17 | 278–394 | 238–337 | 208–295 |
| Tomatoes, peppers and other fruiting plants | 18–30 | 417–694 | 357–595 | 313–521 |
Open the full DLI calculator to compare with your plant and print it
Sources
- Iowa State University Extension: How to determine how much supplemental light to provide indoor plants
- Iowa State University Extension: Important considerations for providing supplemental light to indoor plants
- Torres & Lopez, Purdue University Extension HO-238: Measuring daily light integral in a greenhouse
- Allred & Mattson, Cornell University, in Produce Grower: Dialing in microgreens production