Grow Light for Rebutia: Crown Blooms on Small Cacti
A grow light for rebutia can turn a shelf of small cacti into a ring of color. These clumping cacti from the Andes flower freely when they get enough light.
The short answer
Set fluorescent tubes or an LED panel 6 to 12 inches above rebutia for 14 to 16 hours a day. Minnesota Extension lists rebutia among cacti that are easy to flower indoors. Good light with dry soil and cool winter nights sets the buds.
How much light does rebutia need?
Minnesota Extension says cacti need lots of light in a bright sunny window. Iowa State says succulents need ten or more hours of light a day indoors. Low light gives tall pale growth. The Henry Shaw Cactus and Succulent Society notes that more light brings out purple tones in some rebutias but that high light with heat can scar them.
A sunny window gives cacti lots of light and a grow light fills in a dim spot. Change light slowly to avoid scarring.
How do you light a shelf of small cacti?
For a shelf, Minnesota Extension hangs cool white or daylight fluorescent tubes 6 to 12 inches over the pots and runs them 14 to 16 hours a day. Iowa State uses LED or fluorescent fixtures within 12 inches, timed for 12 to 16 hours. Minnesota Extension’s lighting page notes that LEDs do not produce too much heat and lets flowering plants sit 6 to 12 inches below.
| Option | What it does | Source |
|---|---|---|
| LED panel | Low heat | Lighting for indoor plants and starting seeds, UMN Extension |
| Fluorescent tube | 6 to 12 inches above the plants | Cacti and succulents, UMN Extension (houseplants) |
| Timer | Runs 12 to 16 hours each day | Common Problems and Issues of Succulents, Iowa State University Extension and Outreach Yard and Garden |
How do you get rebutia to flower?
Minnesota Extension lists rebutia as easy to flower indoors with good light plus dry soil and cool nights. The Henry Shaw society says rebutias often flower heavily and may bloom twice in a year. Buds open low on the stem sides.
Cool nights and a dry winter help bring bloom. In winter water only to stop shrinking.
Troubleshooting
Pale stretched growth: low light. Lower the light or add hours.
Brown or tan patches: a sudden jump in light. Raise the lamp and ease in.
Soft yellow growth: overwatering. Wait for dry soil before watering again.
Kind Seed Co shares these plant notes for growers of all kinds. For more on lighting see grow lights for cannabis and led light distance cannabis. Read grow light timers for timer setups. Browse cannabis seeds for our seed range.
Sources
- Cacti and succulents, UMN Extension (Gardening in Minnesota)
- Lighting for indoor plants and starting seeds, UMN Extension
- Common Problems and Issues of Succulents, Iowa State University Extension and Outreach Yard and Garden
- Rebutia (2020), Henry Shaw Cactus and Succulent Society
FAQ
Do rebutia flower every year?
The Henry Shaw Cactus and Succulent Society says rebutias often flower heavily and may bloom twice in a year.
How many hours of light do they need?
Minnesota Extension suggests 14 to 16 hours a day under fluorescent tubes. Iowa State suggests 12 to 16 hours under grow lights.
Can rebutia grow on a windowsill?
Yes. Minnesota Extension says a windowsill gives the light and cool nights cacti need to flower.
Where do rebutia flowers form?
The Henry Shaw society says flowers are usually borne on the lower sides of the stems.
What if rebutia gets tall and thin?
That is a sign of low light. The Henry Shaw society says rebutias often recover with more light and may form pups.
