Grow Light for Strawflower Seedlings Plus Surface Sowing
A grow light for strawflower seedlings gives tiny plants the steady light a window cannot. University of Minnesota Extension says lack of light is the major cause of elongated, skinny stems. It advises lights no more than 4 inches above seedlings, with 2 inches ideal.
The short answer
Set a grow light for strawflower seedlings 2 to 4 inches above the tops and run it 12 to 16 hours a day. University of Minnesota Extension says plants need a dark period each night. University of Maryland Extension says window light is seldom enough, so seedlings stretch and lean toward it and turn out weak.
Why do seedlings need a grow light?
University of Maryland Extension says natural light from a window is seldom enough for sturdy seedling growth.
Seedlings usually lean and stretch toward the window. Maryland says they will not produce sturdy plants.
University of Minnesota Extension says windowsill seedlings tend to be too tall, with thin, bent stems.
How close should lights hang?
Minnesota says to set lights no more than 4 inches above seedling tops. As close as 2 inches is ideal.
Hang lights from chains so they are easy to lift as plants grow.
Run lights 12 to 16 hours daily. Minnesota says a simple timer can switch them on and off.
| Setting | Guide | Reason |
|---|---|---|
| Height | 2 to 4 inches above tops | Stops stretching |
| Hours | 12 to 16 daily | Steady growth |
| Dark period | Each night | Normal development |
Source: University of Minnesota Extension plus University of Maryland Extension.
Which tubes suit seedlings?
Maryland says incandescent bulbs give off more heat and less light than fluorescent tubes. They will not produce good transplants alone.
Cool white tubes are the cheapest option. Full spectrum grow lights give a balance of red and blue light.
Maryland adds that grow lights yield thicker stems than cool white tubes.
How to: step by step
- Load cells with sterile seed starting mix.
- Cover light requiring seed with a thin layer of fine vermiculite.
- Hang lights from chains 2 inches above the trays.
- Set a timer for 12 to 16 hours.
- As seedlings grow, raise lights.
- Harden plants off over 2 weeks before planting out.
Troubleshooting
Few sprouts: seed covered too deeply. Use a thin layer of fine vermiculite.
Stretched stems: lights too high. Lower them.
Scorched leaves after moving out: no hardening off. Increase outdoor time gradually.
For related reading see cannabis seedling light schedule, leggy cannabis seedlings plus damping off cannabis seedlings. Kind Seed Co also stocks cannabis seeds.
Sources
- Xerochrysum bracteatum (strawflower), NC State Extension Gardener Plant Toolbox
- Cut flower production, Penn State Extension
- Grow lights for starting seeds indoors, University of Maryland Extension
- Starting seeds indoors, UMN Extension
FAQ
How should seeds that need light be covered?
University of Minnesota Extension says some seeds require light to germinate. Cover them with a thin layer of fine vermiculite. It is porous enough to let light through, yet it holds enough moisture to encourage germination. Most other seeds go in about two times as deep as their width.
How are seedlings hardened off?
University of Minnesota Extension says to move seedlings outside two weeks before planting out. Start with a few hours in shade during the warm afternoon, sheltered from wind. Bring them in before night temperatures drop. Each day leave them out a little longer, so leaves are not scorched by sun or wind.
When does strawflower bloom?
NC State Extension says strawflower blooms from late spring until frost. It can be grown as a short lived tender perennial or as an annual. It grows easily in average to dry soils with moderate drought tolerance. Most plants reach 2 to 3 feet, and some dwarf types stay near 12 inches.
Why is strawflower grown for drying?
NC State Extension says the bracts have petals like stiff paper that unfold into bright rings. The flowers retain their shape and color when dried, so strawflower is grown for the dried flower market. Cut fresh flowers also last a long time. The common name comes from the straw like texture of the bracts.
Does strawflower need pinching?
NC State Extension describes strawflower as low maintenance. It says regular deadheading encourages side shoots and more blooms. A light annual pruning encourages branching, which results in a larger number of flowers. Plants can also be cut back once flowering is complete at the end of the season.
