Grow Light for Pentas: Egyptian Star Clusters Under Lights
A grow light for pentas gives this sun loving plant the bright light it needs to form its star shaped flower clusters indoors. Pentas is also called Egyptian star cluster.
The short answer
UF/IFAS advises planting pentas in full sun with well drained soil. University of Missouri Extension notes supplemental electric light is usually the easiest way to give plants enough light indoors. Use a full spectrum LED close above the plant on a timer.
How much light does pentas need indoors?
NC State Extension notes full sun encourages pentas blossoms, though the plant will tolerate some shade. North of zone 10 it is usually grown indoors as a houseplant in a sunny, humid room. Missouri notes high light plants need at least 1,000 footcandles.
| Factor | Target | Why |
|---|---|---|
| Light level | At least 1,000 footcandles | High light plants (Missouri) |
| Lamp distance | Plant tips 6 to 12 inches away | Light drops fast with distance (Missouri) |
| Hours with window light | 12 to 14 hours | Supplements daylight (Missouri) |
| Daily maximum | No more than 16 hours | Plants need darkness (Maryland) |
| Humidity | High | Sunny room with high humidity (NC State) |
Source: University of Missouri, University of Maryland plus NC State Extension.
Where should a grow light sit for pentas?
Missouri advises placing most plants with their tips 6 to 12 inches from the light source, since intensity drops rapidly with distance. Hang the fixture so it can rise as the plant grows.
How many hours should the light run?
Missouri notes plants with no outdoor light need 16 to 18 hours a day, while 12 to 14 hours may do if some window light reaches them. Maryland advises no more than 16 hours in total. Run lights alongside window light, per Missouri.
How to: step by step
- Place pentas in your sunniest window.
- Add a full spectrum LED above the plant.
- Hang the light 6 to 12 inches above the tips.
- Put the light on a timer for a steady day length.
- Watch new growth for color plus spacing between leaves.
- Adjust height or hours as the plant responds.
Troubleshooting
Long, weak stems: low light. Lower the lamp or add hours.
Pale or browning leaves: too much light. Maryland notes excess light turns leaves pale plus brown, so raise the lamp.
Leggy early growth: UF/IFAS notes you can pinch back early growth for bushier plants.
For lighting see grow lights for cannabis plus led light distance cannabis. Read grow light timers plus cannabis seeds. Kind Seed Co also stocks cannabis seeds.
Sources
- Pentas, UF/IFAS Gardening Solutions
- Pentas lanceolata (Egyptian star cluster), NC State Extension Gardener Plant Toolbox
- Lighting for indoor plants, University of Maryland Extension
- Lighting indoor houseplants (G6515), University of Missouri Extension
FAQ
Can pentas grow under a regular LED bulb?
University of Missouri Extension notes LED plant lights can be made to give the red plus blue light plants need. Household bulbs give less useful light. Missouri also notes high light plants are harder to grow under home lights, so use a plant LED close above the foliage.
Should the light run all night?
No. University of Maryland Extension notes most plants need a period of darkness to develop properly plus advises no more than 16 hours of light a day in total. University of Missouri Extension suggests 12 to 14 hours when some window light also reaches the plant.
Should spent pentas flowers be removed?
UF/IFAS notes pentas produce red, pink or white flowers through the summer plus advises pinching back early growth for bushier plants. The sources do not set a rule for spent blooms, so trim faded clusters if you like a tidy plant. Feed with a balanced fertilizer about every six weeks, per UF/IFAS.
Do plants need a dark period?
University of Maryland Extension notes most plants require a period of darkness to develop properly. It advises lighting them no more than 16 hours a day in total, especially when artificial light adds to natural light. Set a timer so the lamp shuts off each night.
How big do pentas get?
UF/IFAS notes most pentas grow about 15 inches wide plus 2 to 3 feet tall, so leave room for them in beds. Closer spacing is fine in container gardens. Raise the grow light as the plant gains height so the tips stay 6 to 12 inches below it, per Missouri.
