Grow Light for Nasturtium Seedlings: Quick Starts
A grow light for nasturtium seedlings stops these quick starts from stretching during a short indoor stay. University of Wisconsin Extension notes that nasturtiums can be sown directly in the garden or started indoors in peat pots. Indoors, use single pots, close lamps plus an early transplant.
The short answer
Start nasturtiums indoors in peat pots 4 to 6 weeks before the last expected spring frost, as University of Wisconsin Extension suggests. Hang fluorescent or LED lights 2 to 4 inches above the seedlings for 12 to 16 hours a day. Transplant once all danger of frost has passed.
Why grow nasturtiums indoors only briefly?
They grow fast. University of Wisconsin Extension notes that seedlings generally come up within 7 to 10 days plus grow quickly in warm weather. University of Minnesota Extension lists nasturtium among the flowers sown in early April, with only 5 to 6 weeks indoors.
A short stay means less time to stretch. Peat pots let each seedling go into the ground without disturbing its roots.
| Stage | Light distance | Daily hours |
|---|---|---|
| Seedlings indoors | 2 to 4 inches above tops | 12 to 16 hours |
| Garden planting | Full sun | Partial shade cuts flowering |
Source: University of Maryland Extension plus University of Wisconsin Extension.
How close should lights hang?
Very close. University of Maryland Extension advises lights no more than 4 inches above the seedling tops, with 2 inches as ideal. It suggests 12 to 16 hours of light daily.
Raise the fixture as these fast seedlings grow so the gap stays the same.
Should seeds be soaked?
It helps. University of Wisconsin Extension notes that soaking the seed for a few hours or overnight before planting can improve germination. Sow seeds half an inch deep, since they need darkness to germinate.
Seed typically germinates in a week to ten days, depending on soil temperature.
How to: step by step
- Soak seeds a few hours or overnight if you like.
- Sow half an inch deep in single peat pots.
- Place lamps 2 to 4 inches over the seedlings.
- Give 12 to 16 hours of light daily.
- Water until the mix is moist, not soggy.
- Plant out early after frost danger passes.
Troubleshooting
Stretched stems: lights too high. Lower them to 2 to 4 inches above the tops.
Transplant wilt: root disturbance. Use single peat pots so roots stay intact.
Few flowers later: rich soil or extra feeding. University of Wisconsin Extension notes that heavy fertilization promotes leaf growth plus reduces flowering.
For related reading see cannabis seedling light schedule, leggy cannabis seedlings plus potting up cannabis seedlings. Kind Seed Co also stocks cannabis seeds.
Sources
- Nasturtium, Tropaeolum majus, University of Wisconsin Extension
- Tropaeolum majus, NC State Extension Plant Toolbox
- Grow lights for starting seeds indoors, University of Maryland Extension
- Starting seeds indoors, University of Minnesota Extension
FAQ
Can nasturtiums be direct sown?
Yes. University of Wisconsin Extension notes that seed can be sown directly in the garden in late spring to early summer once all danger of frost has passed. Sow seeds half an inch deep plus 10 to 12 inches apart. Indoor starts in peat pots give an earlier display.
How long do seeds take to sprout?
University of Wisconsin Extension notes that seed typically germinates in a week to ten days, depending on soil temperature. Seedlings grow quickly in warm weather. Soaking the seed for a few hours or overnight before planting can improve germination, so many gardeners soak seeds the night before sowing.
Do nasturtiums need full sun?
Yes. University of Wisconsin Extension advises planting nasturtiums in well drained soil in full sun. They will grow in partial shade but will not bloom well there. NC State Extension adds that some afternoon shade helps in hot summers, so a bright spot with shelter from late heat suits them.
Why are nasturtiums all leaves?
Usually too much fertilizer. University of Wisconsin Extension advises skipping fertilizer except on extremely poor soil, since high fertilization promotes leaf growth plus reduces flowering. NC State Extension agrees that feeding increases foliage but decreases flowering. Poor to average, well drained soil gives the most blooms.
How can nasturtiums bloom longer?
Deadhead them. University of Wisconsin Extension notes that deadheading or picking the flowers will prolong blooming, plus plants continue until frost. Plants also self seed readily. In warm, mild climates they bloom plus seed year round, while reseeding is not a problem in cold climates.
