Grow Light for Celosia Seedlings: Warm Mix Plus Bright Light
A grow light for celosia seedlings gives this heat loving annual a bright start indoors. NC State Extension notes that celosia prefers full sun plus thrives in heat. Warm the mix from below, hang lights close plus wait until after the last frost to plant out.
The short answer
Hang fluorescent or LED lights 2 to 4 inches above celosia seedlings for 12 to 16 hours a day, as University of Minnesota Extension advises. Warm the potting mix from below so seeds sprout sooner. NC State Extension notes that celosia can be started indoors plus transplanted after the last frost.
Why does celosia need warmth?
NC State Extension notes that celosia prefers full sun plus thrives in heat and humidity. University of Missouri Extension lists plume celosia as frost free plus easily grown.
University of Missouri Extension groups such plants as tender annuals. These do not tolerate cool weather and should not be planted until the danger of frost has passed plus the soil has warmed.
University of Minnesota Extension explains that seeds of most plants germinate sooner when the potting mix is warm. Bottom heat may also help prevent damping off in tiny seedlings.
How close should lights hang?
University of Minnesota Extension advises lights no more than 4 inches above the tops of seedlings. As close as 2 inches is ideal.
Plants need 12 to 16 hours of light daily, the same source notes.
University of Maryland Extension notes that window light is seldom enough for good seedling growth. Windowsill seedlings usually stretch plus lean toward the glass.
| Setting | Guideline | Source note |
|---|---|---|
| Light height | 2 to 4 inches above seedlings | 2 inches is ideal |
| Light hours | 12 to 16 hours daily | Use a timer |
| Mix warmth | Warm from below | Seeds sprout sooner |
| Hardening off | Two weeks | Start in afternoon shade |
Source: University of Minnesota Extension plus University of Maryland Extension.
When should celosia go outside?
NC State Extension notes that celosia seeds can be started indoors plus transplanted after the last frost. Direct sowing in the garden can also work.
University of Minnesota Extension advises hardening off over two weeks. Start with a few hours outside in shade during the warmth of the afternoon, out of the wind.
University of Missouri Extension notes that a cloudy day is ideal for transplanting. Tall spindly plants can be cut back to about half their height before setting out.
How to: step by step
- Load cells with moist seed starting mix.
- Rest the tray on a heat mat for warmth below.
- Hang lights 2 to 4 inches above the seedlings.
- Run lights 12 to 16 hours daily on a timer.
- Harden seedlings off over two weeks.
- Transplant after the last frost once the soil has warmed.
Troubleshooting
Slow sprouting: cool mix. Add bottom warmth.
Stretched stems: lights too high. Lower them to 2 to 4 inches.
Stunted plants outdoors: planted out too early. Wait until the soil has warmed.
For related reading see cannabis seedling light schedule, seedling heat mats for cannabis plus hardening off cannabis seedlings. Kind Seed Co also stocks cannabis seeds.
Sources
- Celosia argentea var. cristata (cockscomb), NC State Extension Gardener Plant Toolbox
- Flowering annuals: characteristics plus culture (G6629), University of Missouri Extension
- Grow lights for starting seeds indoors, University of Maryland Extension
- Starting seeds indoors, UMN Extension
FAQ
Can celosia be direct sown?
Yes. NC State Extension notes that celosia seeds can be started indoors plus transplanted after the last frost or direct sown in the garden. An indoor start under lights gives earlier plants. Direct sowing works once the soil has warmed, since tender annuals do not tolerate cool weather.
How long does celosia bloom?
NC State Extension notes that celosia blooms from late spring to the first frost. University of Missouri Extension adds that celosia flowers can be dried for winter decoration. Deadheading spent flowers helps if unwanted reseeding is a concern, according to NC State Extension.
Why do celosia seedlings damp off?
University of Minnesota Extension describes damping off as the death of tiny seedlings due to pathogens at the surface of the potting mix. Bottom heat can help prevent it. Cooler soil temperatures can lead to seedling death due to disease, the same source adds.
What lamp type suits celosia seedlings?
University of Maryland Extension notes that fluorescent lights are the easiest way to control growing conditions for seedlings. Incandescent bulbs give off more heat plus less light and will not produce good transplants by themselves. University of Minnesota Extension also lists LED lights as a good choice.
What if celosia transplants are tall and spindly?
University of Missouri Extension advises cutting tall spindly plants back to about half their original height before transplanting. Lowering the lights to 2 to 4 inches above seedlings helps prevent the stretch in the first place, as University of Minnesota Extension advises.
