Grow Light for Ranunculus: Early Indoor Starts
A grow light for ranunculus helps tubers started indoors grow sturdy leaves before planting out. NC State Extension describes Persian buttercup as a tuberous rooted perennial that does well in cool spring weather. Set tubers claws down in moist mix, then grow sprouts under close lamps.
The short answer
Start ranunculus tubers indoors, then plant them outside in spring before hot summer weather, as NC State Extension suggests. Set them with root claws down. Once leaves show, hang fluorescent or LED lights a few inches above them for about 16 hours a day.
Why start ranunculus indoors?
To beat the heat. NC State Extension notes that these plants do well in cool spring weather plus go dormant in summer. An indoor start gives leaves a head start, so plants bloom before hot weather sets in.
NC State Extension adds that tubers can go straight into the ground several weeks before the last frost date instead. Indoor starts suit gardeners who want more control.
| Stage | Light distance | Daily hours |
|---|---|---|
| Sprouts indoors | A few inches above leaves | 16 hours, 18 at most |
| Garden planting | Full sun | Cool spring weather |
Source: Illinois 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 tops, with 2 inches as ideal. Illinois Extension runs plants on a timer for 16 hours of light per day, with 18 hours as the maximum for seedlings.
Illinois Extension notes that without enough light, plants become leggy, with stretched stem sections between the leaves.
When should sprouted tubers be planted?
In spring, before summer heat. NC State Extension notes that plants are semi hardy in North Carolina, with injury below 28°F. Plant tubers 2 inches deep plus 6 to 8 inches apart.
Choose sandy soil with excellent drainage in full sun. NC State Extension notes that ranunculus does not tolerate heavy clay soils.
How to: step by step
- Place tubers claws down in barely moist mix.
- Leave the tray somewhere cool while roots form.
- Shift sprouts under lamps when leaves appear.
- Set lamps 2 to 4 inches over the leaves.
- Use a timer for about 16 hours of light daily.
- Set out 2 inches deep in spring before hot weather.
Troubleshooting
Soft, rotting tubers: a wet mix. NC State Extension notes that ranunculus needs excellent drainage, so use barely moist, sandy mix.
Pale, stretched leaves: weak light. Lower the lamp to a few inches above the leaves.
Few blooms: planted in heat. NC State Extension notes that plants do well in cool spring weather plus go dormant in summer, so plant out earlier.
For related reading see grow lights for cannabis, leggy cannabis seedlings plus hardening off cannabis seedlings. Kind Seed Co also stocks cannabis seeds.
Sources
- Ranunculus asiaticus, NC State Extension Plant Toolbox
- Bulbs, University of Maryland Extension
- Grow lights for starting seeds indoors, University of Maryland Extension
- Supplemental lighting for indoor seed starting, Illinois Extension
FAQ
Which way up do ranunculus tubers go?
Claws down. NC State Extension advises planting tubers 2 inches deep plus 6 to 8 inches apart, with root claws down. University of Maryland Extension groups ranunculus with structures that are disc shaped, with buds on top plus roots below, so the claws mark the root side.
When should tubers go into the ground?
NC State Extension suggests planting tubers several weeks before the last frost date. Tubers can also be started indoors plus planted outside in spring, before the onset of hot summer weather. Plants are semi hardy in North Carolina, with injury at temperatures below 28°F, so watch late cold snaps.
Do ranunculus need full sun?
Yes. NC State Extension notes that ranunculus does well in full sun with medium moisture plus excellent drainage. Hybrids prefer mild winters, cool dry summers plus sandy soil. They do not tolerate heavy clay soils, so raised beds or containers help in heavy ground.
Can ranunculus grow in pots?
Yes. NC State Extension notes that although ranunculus are perennial, they are often grown as annuals or grown in containers as florist plants. A pot with sandy, well drained mix suits them. Grow the container in full sun during cool spring weather for the most blooms.
Can tubers be saved for next year?
Yes. NC State Extension notes that plants go dormant in summer. To save spent plants for next season, dig up the tubers, cut off the tops plus store them in a dry, cool location. Deadheading spent flowers during the season also encourages more blooms.
