Do seeds need light to germinate?
Some do, some need darkness, and many do not mind. NC State Extension lists common ones.
NC State's list
| Needs light | Needs darkness | Either |
|---|---|---|
| Ageratum, begonia, browallia, coleus, geranium, impatiens, lettuce, nicotiana, petunia, snapdragon | Centaurea, larkspur, pansy (viola), phlox, portulaca, verbena | Alyssum, aster, balsam, broccoli, cabbage, cauliflower, celosia, cosmos, cucumber, dahlia, dianthus, eggplant, marigold, muskmelon, pepper, squash, tomato, vinca, watermelon, zinnia |
What to do
- Light germinators. Oklahoma State says to leave these on the surface or only partly covered. The University of Arizona says tiny seeds are best left uncovered or covered with a fine dusting of vermiculite, and settled with a gentle spray.
- Dark germinators. The University of Arizona says to cover large seeds with planting medium and very fine seeds with flat newspaper.
- Either. Sow at the depth on the seed packet and cover lightly, as Oklahoma State says.
Light for seedlings is a different question
Once seeds have sprouted, they need strong light every day. That is what the shelf lights are for. See hours per day and hanging height. Seeds that need darkness to germinate still need light as soon as they emerge.
Sources
- NC State Extension, Ashe County: Indoor seed starting guide (PDF)
- Oklahoma State University Extension: Tips for starting seeds at home (2025)
- University of Arizona Extension: Sowing and planting seeds (PDF)
Related
- Seed starting mix vs garden soil
- Seed germination temperature chart
- How to Water Seedlings: Bottom Watering and Moisture
- When and How to Fertilize Seedlings
- Window Light vs Grow Light for Seedlings
- Seedling Problems: Leggy, Purple, Wilting and Leaning
- Seed starting shelf light calculator
- Main guide to grow lights for a seed starting shelf