Grow Lights for Marigold Seedlings Before Spring
Grow lights for marigold seedlings help you start marigolds indoors a few weeks before spring planting. University of Minnesota Extension notes marigolds are very easy to grow plus grow fast. Hang lights 2 to 4 inches above the trays, run them 12 to 16 hours a day plus plant out after frost.
The short answer
Sow marigold seed about 1/4 inch deep, hold the mix at 70°F to 75°F until sprouting plus hang lights 2 to 4 inches above the seedlings for 12 to 16 hours a day. University of Minnesota Extension advises planting transplants out once the danger of frost is gone.
When should marigolds be started indoors?
University of Minnesota Extension gives about 10 weeks before the outdoor planting date on its marigold page. Its seed starting table lists African marigolds in mid March at 9 weeks plus French plus gem types in early April at 5 to 6 weeks.
| Stage | Task | Light |
|---|---|---|
| Sowing | Sow 1/4 inch deep under a cover | Sprouts in 5 to 8 days at 70°F to 75°F |
| Seedlings | Grow at 65°F to 75°F by day | Lights 2 to 4 inches above for 12 to 16 hours |
| Small plants | Pinch the top for branching | Raise lights as plants grow |
| After frost | Harden off for two weeks | Full sun all day outdoors |
Source: University of Minnesota Extension.
How close should lights be?
University of Minnesota Extension advises lights no more than 4 inches above seedling tops, with 2 inches ideal, plus notes lack of light is the major cause of elongated, skinny stems. It also advises against leaving lights on continuously, since many plants need a dark period each night.
When can marigolds go outside?
University of Minnesota Extension notes transplants can go out when the danger of frost is gone plus that marigolds need full sun all day to bloom all season. Harden seedlings off over two weeks first. NC State Extension notes marigolds can grow in full or partial sun, but full sun encourages blooms.
How to: step by step
- Sow seed 1/4 inch deep about 10 weeks before planting out.
- Cover the tray plus hold the mix at 70°F to 75°F.
- Hang lights 2 to 4 inches above the seedlings.
- Run lights 12 to 16 hours a day on a timer.
- Pinch young tops for bushier growth.
- Harden off plus transplant after the last frost.
Troubleshooting
Leggy seedlings: low light. Drop the lights closer.
Seedlings collapse: damping off. Use bottom heat plus pour off extra water.
Lots of leaves but few flowers outdoors: too much fertilizer. Feed less, as marigolds need little.
For related reading see grow lights for cannabis, cannabis seedling light schedule plus hardening off cannabis seedlings. Kind Seed Co also stocks seeds for indoor growers.
Sources
- Marigolds, University of Minnesota Extension
- Marigolds, UF/IFAS Gardening Solutions
- Tagetes (marigold), NC State Extension Gardener Plant Toolbox
- Starting seeds indoors, University of Minnesota Extension
FAQ
How long do marigold seeds take to sprout?
University of Minnesota Extension notes marigold seeds germinate in 5 to 8 days at 70°F to 75°F. It advises sowing about 1/4 inch deep, covering seeds fully plus using a plastic cover over the tray to hold moisture. After germination, grow plants at 65°F to 75°F by day.
Do marigolds need darkness at night?
University of Minnesota Extension advises against running seedling lights continuously, since many plants need some dark period each night to develop properly. It suggests 12 to 16 hours of light daily set on a simple timer, so the lights turn off plus on automatically each day.
Can marigolds bloom indoors?
NC State Extension lists houseplant use for marigolds plus notes full sun encourages blooms. University of Minnesota Extension notes they need full sun all day to bloom all season, so flowering under indoor lights is likely to be lighter than on plants set outside in a sunny bed.
Which marigold types are easiest from seed?
University of Minnesota Extension notes marigolds are very easy to grow plus describes three common types. French marigolds are compact at 6 to 12 inches, Signet types reach 6 inches or less, while African types can reach 3 to 4 feet plus may need staking outdoors.
Should I pinch marigold seedlings?
It is optional. University of Minnesota Extension notes that pinching off the top of the plant while it is still small promotes more branches for a bushier plant. It also notes that deadheading spent blooms outdoors helps plants produce more flowers rather than setting seed.
