Grow Light for Rudbeckia Seedlings: Early Starts
A grow light for rudbeckia seedlings gives black eyed Susans an early indoor start so plants are ready to bloom in their first summer. NC State Extension notes that Rudbeckia hirta blooms the first year when planted from seed in early spring. Sow indoors, hang lamps close plus harden off.
The short answer
Start rudbeckia indoors about 10 to 11 weeks before planting out, as University of Minnesota Extension suggests. Hang fluorescent or LED lights 2 to 4 inches above the seedlings plus run them 12 to 16 hours a day. Harden plants off, then set them in full sun to partial shade.
Why start rudbeckia indoors?
For first year flowers. NC State Extension describes black eyed Susan as a fast growing biennial or short lived perennial native to the eastern United States. Because it blooms the first year from an early spring sowing, it is often mistaken for an annual.
University of Minnesota Extension lists rudbeckia among the flowers sown in early March, with 10 to 11 weeks indoors.
| Stage | Light distance | Daily hours |
|---|---|---|
| Seedlings indoors | 2 to 4 inches above tops | 12 to 16 hours |
| Garden planting | Full sun to partial shade | 6 or more hours of direct sun preferred |
Source: University of Maryland Extension plus NC State 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.
The same source notes that seedlings grown under fluorescent or LED lights do much better than seedlings relying on natural light alone. Raise the fixture as plants grow.
When should seedlings move outside?
After hardening off. University of Minnesota Extension schedules hardening off for all seedlings in early to mid May in Minnesota. Adjust that timing to your own frost date.
NC State Extension advises moist, well drained soil in full sun to partial shade. Moderate fertility gives a fine flower show, so avoid spots near lawns that get extra nitrogen.
How to: step by step
- Sow seed inside in early March for 10 to 11 weeks under lamps.
- Heat the room above 60°F.
- Mount lamps 2 to 4 inches over the seedlings.
- Supply 12 to 16 hours of light daily.
- Repot as seedlings get bigger.
- Acclimate plus plant in full sun to partial shade.
Troubleshooting
Leggy seedlings: weak light. Lower the lamp to 2 to 4 inches above the tops.
Slow growth: a cold room. University of Minnesota Extension advises air above 60°F for seed starting.
White powder on leaves later: powdery mildew. NC State Extension lists Rudbeckia hirta as susceptible, so space plants well for air flow.
For related reading see cannabis seedling light schedule, leggy cannabis seedlings plus hardening off cannabis seedlings. Kind Seed Co also stocks cannabis seeds.
Sources
- Rudbeckia hirta, NC State Extension Plant Toolbox
- Rudbeckia fulgida, NC State Extension Plant Toolbox
- Grow lights for starting seeds indoors, University of Maryland Extension
- Starting seeds indoors, University of Minnesota Extension
FAQ
Does rudbeckia bloom the first year?
Often, yes. NC State Extension notes that Rudbeckia hirta blooms in the first year when planted from seed in early spring, which is why it is often mistaken for an annual. An indoor start under lights gives seedlings extra size before they reach the garden.
Can rudbeckia self sow?
Yes. NC State Extension notes that Rudbeckia hirta freely self seeds plus usually remains in the garden. Its flowers have a brown or green domed center ringed by bright yellow or orange ray florets. With deadheading, the blooms continue for a long stretch after first opening in midsummer.
How much room do plants need?
NC State Extension lists Rudbeckia hirta at 2 to 4 feet tall plus 1 to 2 feet wide. Rudbeckia fulgida reaches 2 to 3 feet tall plus 1 to 2 feet wide. Plan for that mature width when setting out seedlings so air moves freely between plants.
Is rudbeckia a perennial?
It depends on the species. NC State Extension describes Rudbeckia hirta as a biennial or short lived perennial. Rudbeckia fulgida is a herbaceous perennial that spreads by underground stems called rhizomes. It thrives in any but soggy soils plus tolerates drought once established.
Does rudbeckia need full sun?
Mostly. NC State Extension lists full sun, meaning 6 or more hours of direct light a day, for both species. Rudbeckia hirta plus Rudbeckia fulgida also tolerate partial shade. Rudbeckia fulgida bears up under hot humid summers, so it handles tough summer beds once plants settle in.
