Pentas is a lush perennial that can grow as a shrub in tropical regions. Stems are topped by tight 4-inch (10cm) wide clusters of small, star-shaped flowers in white, pink, lilac, or red. One species, Pentas lanceolata, is often grown as a houseplant.
Pentas leaves are oval to lance-shaped and mid-green. Flowers are salver-form with five spreading petals. Pentas make long-lasting cut flowers.
In warm-winter regions, Pentas provide color nearly year-round. Pentas are commonly grown as summer annuals in cold-winter regions.
Pentas is a genus of about 40 species of mainly evergreen perennials. Pentas are native to Africa.
Get to Know Pentas
- Plant type: Tropical perennial or shrub is grown as an annual or houseplant
- Growing zones and range: 10-11
- Hardiness: Tender
- Height and width: 6-18 inches (15-45cm) as an annual; 24 to 36 inches (61-91cm) in a pot; in tropical regions grows as a shrub from 6 to 8 feet (1.8-2.4m) tall
- Foliage: Long, pointed, dark green, fuzzy leaves
- Flowers: Large, tight, round clusters of star-shaped flowers in brilliant shades of pink, salmon, red, and white
- Uses: Grow as a bedding plant, container plant, or specimen shrub depending on the growing zone. Can be grown as a houseplant in cold winter regions.
- Bloom time: Summer
- Common name: Pentas, star cluster flowers, Egyptian star cluster flower
- Botanical name: Pentas lanceolata
- Family: Rubiaceae
- Origin: Forest margins of Arabian Peninsula, tropical Africa, and Madagascar
Where to Plant Pentas
- Plant Pentas in full sun where the sun is not intense; plant in part shade in very hot summer regions.
- Grow in bright light indoors.
- Grow Pentas in humus-rich, well-drained soil.
When to Plant Pentas
- In cold or cool winter regions, set Pentas in the garden in late spring about 3 weeks after the last frost.
- In tropical regions, container-grown Pentas can be planted outdoors at any time of the year.
Planting and Spacing Pentas
- Space Pentas growing as annuals 6 to 18 inches (15-45cm) apart.
How to Water and Feed Pentas
- Keep the soil evenly moist; do not let the soil dry out.
- Fertilize Pentas every 4 to 6 weeks with an all-purpose fertilizer or work a slow-release fertilizer into the soil at planting time.
- Mulch around Pentas to conserve soil moisture.
- Trim spent flowers to encourage further flowering.
- In fall, a few weeks before the first frost bring Pentas indoors to grow in a sunny spot as a houseplant.
- Where Pentas grow as perennials, prune the plant heavily each year before spring growth begins to keep the plant compact.
Growing Pentas as a Houseplant
- Grow Pentas in a room that has average to warm temperature, direct light, and average humidity.
- the medium should be soilless and well-drained and kept evenly moist.
- Fertilize every two weeks while the plant is growing and flowering.
- After the flowers have faded, prune the plants back to half their former size, and use the prunings to root new plants.
- Pinch growing tips to keep the plants bushy and compact.
Pentas Pests and Disease
- Aphids and spider mites can be a problem.
- Sow seed in warm soil in spring.
- Take softwood cuttings any time of the year; root with bottom heat in winter.
Pentas Varieties to Grow
- Pentas lanceolata (P. carnea), Egyptian star cluster, star cluster: erect or prostrate, woody-based evergreen perennial; lance-shaped leaves; bears flat or domed corymbs of long-tubed pink, magenta, blue, lilac, or white flowers; can grow to 6 feet (2m) tall and 3 feet wide; cultivar ‘New Look’ is a dwarf cultivar that grows 6 to 12 inches (15-30cm) tall.
Pentas Frequently Asked Questions
Q: What temperature does Pentas want indoors?
A: Average room temperature most of the year, a minimum of 50°F in winter, 60°F is better.
Q: What light does Pentas want?
A: Give Pentas bright light with some direct sun either early in the morning or late in the afternoon, but not midday sun.
Q: How should I water Pentas?
A: Keep the potting medium moist at all times. Mist leaves occasionally. Reduce watering in winter.
Q: How can I keep Pentas from growing straggly?
A: Pinch off the stem tips regularly to keep Pentas bushy and compact. Don’t let the plant grow taller than about 18 inches. After the flowers have faded, you can prune the plant back to half its former size. Use the prunings to root new plants.