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DLI by plant: how much light houseplants, herbs and seedlings need

Updated October 2026

Quick answerMost foliage houseplants need a DLI of about 3–10 mol/m²/day, herbs and succulents 12–17, and tomatoes and peppers 18 or more. The table also shows the grow light strength (PPFD) that delivers each range in 12 or 16 hours.

Plant group and examplesDLI target
(mol/m²/day)		PPFD for 12 h
(µmol/m²/s)		PPFD for 16 h
(µmol/m²/s)		Source
Low-light houseplants Snake plant, Chinese evergreen, parlor palm, heart-leaf philodendron, Boston fern 3–669–13952–104Iowa State
Medium-light houseplants Pothos, spider plant, dracaena, rubber plant, fiddle-leaf fig, prayer plant, peperomia 6–10139–231104–174Iowa State
African violets and moth orchids Saintpaulia, Phalaenopsis 6–10139–231104–174Purdue
Microgreens Arugula (about 9), mizuna and mustard (12 or more) 9–12208–278156–208Cornell
Vegetable and flower seedlings Tomato, pepper, marigold, salvia and other transplants 10–12231–278174–208Purdue
Succulents and cacti Jade plant, echeveria, aloe, ponytail palm, cacti 12–16278–370208–278Iowa State
Herbs and leafy greens Basil, parsley, lettuce (head lettuce about 17), spinach 12–17278–394208–295Iowa State
Tomatoes, peppers and other fruiting plants Tomatoes, peppers, strawberries 18–30417–694313–521Iowa State
DLI chart: daily light integral ranges by plant. Low-light houseplants 3 to 6, Medium-light houseplants 6 to 10, African violets and moth orchids 6 to 10, Microgreens 9 to 12, Vegetable and flower seedlings 10 to 12, Succulents and cacti 12 to 16, Herbs and leafy greens 12 to 17, Tomatoes, peppers and other fruiting plants 18 to 30 mol per square meter per day.
Printable DLI chart. Download the chart (PNG) or open it full size to print.

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How to read the table

Stay inside the range for steady, healthy growth. Below the low end, plants stretch toward the light, grow slowly, lose lower leaves and flower poorly. Well above the high end, sensitive leaves can bleach or scorch, especially if the light is very close.

The PPFD columns tell you what to look for on a grow light’s chart at the distance you plan to hang it. For example, basil at 14 hours needs about 238–337 µmol/m²/s.

Notes on specific groups

Houseplants

Plant examples follow University of Illinois Extension’s light lists. Purdue University lists several foliage plants, African violets and moth orchids as acceptable from a DLI of about 2–4, with the best quality at 6–10.

Seedlings

Purdue found seedling quality improved as DLI increased up to about 12. Iowa State places seedlings between the upper medium and lower high range.

Microgreens

Cornell University research found arugula may benefit from a DLI up to about 9, and mizuna and mustard from 12 or more. Microgreens need less light than head lettuce, which grows best at about 17.

Tomatoes and peppers

These need the most light of any common indoor crop. Purdue lists a minimum of about 10–12 and good growth at 14–20, while Iowa State puts fruiting crops at 18–30. Most people can’t reach these levels from a window and need a strong grow light.

Check your own plant with the calculator, or read how many hours to run your grow light.

Sources

  1. Iowa State University Extension: Important considerations for providing supplemental light to indoor plants
  2. Torres & Lopez, Purdue University Extension HO-238: Measuring daily light integral in a greenhouse
  3. University of Illinois Extension: Houseplants, lighting
  4. Allred & Mattson, Cornell University, in Produce Grower: Dialing in microgreens production