Pentas
( PEN - tas )
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At-A-Glance InformationPentas, or Star Clusters, is a genus of flowering perennials (often grown as annuals) that need full sun and regular water to perform well. Flowers typically bloom in shades of red, purple, white, or pink and are attractive to butterflies and other pollinators. These small shrubby plants have hairy deep green leaves and are native to tropical and southern Africa, the Comoros, Madagascar, and the Arabian Peninsula. Plant Star Clusters in mixed beds, containers, or in pollinator, cottage or informal gardens.
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Pentas Species and Varietals
The genus Pentas is a member of the plant family Rubiaceae and includes 16 species, only one of which is commonly grown as a garden ornamental. The genus name is derived from the Greek word pentas, which means 'a series of five', referring to the flowers on these plants having five petals. Star Clusters grows in all zones as an annual plant. To find your zone, click here: Zone Map.
Pentas lanceolata (Egyptian Starcluster)
This species of flowering perennials that are often grown as annuals that need full sun and regular water. They are native to the tropical regions of Africa and reach 2-3 feet tall and wide. In summer, clusters of small white, pink, lilac or red flowers bloom at stem tips. These make great cut flowers. Leaves are green, and provide a lush background for the bright flowers. There are many cultivars of this species of differing heights, listed below. In general, Lucky Star, BeeBright, and Graffiti varieties tend to be shorter, while Kaleidoscope and Butterfly are taller.
This species of flowering perennials that are often grown as annuals that need full sun and regular water. They are native to the tropical regions of Africa and reach 2-3 feet tall and wide. In summer, clusters of small white, pink, lilac or red flowers bloom at stem tips. These make great cut flowers. Leaves are green, and provide a lush background for the bright flowers. There are many cultivars of this species of differing heights, listed below. In general, Lucky Star, BeeBright, and Graffiti varieties tend to be shorter, while Kaleidoscope and Butterfly are taller.
'Beebright Pink'
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'Butterfly Red'
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'Dwarf White'
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'Falling Star Pink Bicolor'
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'Falling Star Rose'
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'Graffiti Lipstick'
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'Graffiti Violet'
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'Honey Cluster Pink'
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'Kaleidoscope'
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'Lucky Star Deep Pink'
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'New Look Red'
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'Starcluster Lavender'
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'Starcluster White'
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'Starla Red'
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Caring for Pentas
Pentas are considered to be easy-care plants for the garden, and can thrive even when neglected if conditions are right. They are typically planted out in springtime, spaced between 12 and 24 inches apart, depending on the cultivar grown and how large it is at maturity. Plant Pentas in full sun; ideally they should be getting about 6 hours of direct sun each day. They can be grown in partial shade, as well, but will not flower as profusely. Ensure that soil is well-draining, rich in nutrients, and has a neutral pH (around 7.0). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Water newly planted Pentas flowers regularly to help them develop strong root systems. At maturity, these plants have a moderate resistance to drought, and can get by on rainwater alone for most of the year. Irrigate in summertime or during extended periods of drought. Make sure to water these flowers from their base, as excess water on foliage can cause fungal issues, especially during hot, humid weather.
Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. These plants are not heavy feeders, and this should be sufficient to provide the necessary nutrients for the active growing and flowering seasons. Prune off spent flower heads when they have faded (unless you will be harvesting seeds for propagation). Remove any dead, damaged, or diseased foliage at any time. At the end of the growing season, Pentas plants are typically pulled and composted, though in mild-weather areas they can be left in the ground over winter and will come back the following spring.
Growing Pentas in Containers
Pentas flowers do very well in containers, and look great when several plants are grouped together in a large pot. Ensure that the pot you are using has adequate drainage holes on the bottom, and that it is filled with an easily-drainable substrate. A good pot size is about an inch or two wider than the specimen being planted. Water thoroughly after planting and allow soil to settle into the pot. Mulch the top of the pot, ensuring that the mulch does not touch any of the stems, as this can lead to fungal issues. Doing this will help to suppress weed growth, maintain consistent soil temperatures, and increase soil moisture retention. As the plant establishes itself in its new home, make sure to regularly water it so it can develop a strong root system. When established, these flowers are considered moderately drought-tolerant, though they will perform better with regular irrigations. Pentas grown in pots will need more water than those grown in the ground. Prune off spent flower heads as they appear, and at the end of the season, remove the plants unless you are in a mild-winter area.
Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. These plants are not heavy feeders, and this should be sufficient to provide the necessary nutrients for the active growing and flowering seasons. Prune off spent flower heads when they have faded (unless you will be harvesting seeds for propagation). Remove any dead, damaged, or diseased foliage at any time. At the end of the growing season, Pentas plants are typically pulled and composted, though in mild-weather areas they can be left in the ground over winter and will come back the following spring.
Growing Pentas in Containers
Pentas flowers do very well in containers, and look great when several plants are grouped together in a large pot. Ensure that the pot you are using has adequate drainage holes on the bottom, and that it is filled with an easily-drainable substrate. A good pot size is about an inch or two wider than the specimen being planted. Water thoroughly after planting and allow soil to settle into the pot. Mulch the top of the pot, ensuring that the mulch does not touch any of the stems, as this can lead to fungal issues. Doing this will help to suppress weed growth, maintain consistent soil temperatures, and increase soil moisture retention. As the plant establishes itself in its new home, make sure to regularly water it so it can develop a strong root system. When established, these flowers are considered moderately drought-tolerant, though they will perform better with regular irrigations. Pentas grown in pots will need more water than those grown in the ground. Prune off spent flower heads as they appear, and at the end of the season, remove the plants unless you are in a mild-winter area.
Propagation
Pentas, or Starflower, plants can be propagated best in two ways: by seed or by cutting. If you are looking to create an exact replica of your plant, you will want to use the cutting method of propagation, as propagation by seed does not guarantee a clone of the parent plant.
Propagating Pentas by Seed
To propagate via seed, gather the following materials: a bag, a pot (or planting tray), soil that is one part compost, two parts sand with a little limestone added in, and a spray bottle with water. Follow these directions to propagate your Starflower from seed:
Propagating Pentas by Cutting
The best time to take cuttings from an existing plant is in spring or summer. To propagate by cutting, you'll need clean, sharpened garden shears, potting mix (one part compost, two parts sand and a little limestone added in), a pot (or pots, depending on how many cuttings you'll be taking), rooting hormone and a pencil. Once you've gathered your materials, follow these instructions:
Propagating Pentas by Seed
To propagate via seed, gather the following materials: a bag, a pot (or planting tray), soil that is one part compost, two parts sand with a little limestone added in, and a spray bottle with water. Follow these directions to propagate your Starflower from seed:
- In late summer, leave some of flowers on your existing plant and allow them to come to seed. Remove the seed pod cluster after it has dried, turned brown and some of the seed pods have begun to open and release their contents. Harvest the seeds from the seed pods and place them in a bag. This plant can self-sow if the conditions are right, but to ensure a new plant from seed, it is best to sow indoors in wintertime. Store your harvested seeds in a cool, dark place until about 10-12 weeks before the last frost of spring in your area.
- Prepare your pots or seed trays with your potting mix and water to ensure drainage is occurring. Plant more seeds than you want new plants, as not all seeds will germinate. Place your seeds on top of the soil and cover with more potting mix. Water. Place your seed pots or trays in an indoor area that stays around 60 degrees Fahrenheit and receives bright indirect light, or place them in a greenhouse.
- The seeds will take between 30 and 90 days to germinate. After the danger of frost has passed in your area, you can transplant your new plant outside in its garden location.
Propagating Pentas by Cutting
The best time to take cuttings from an existing plant is in spring or summer. To propagate by cutting, you'll need clean, sharpened garden shears, potting mix (one part compost, two parts sand and a little limestone added in), a pot (or pots, depending on how many cuttings you'll be taking), rooting hormone and a pencil. Once you've gathered your materials, follow these instructions:
- Choose a Pentas plant to propagate. It should be a healthy plant, with new growth and should get some water the night before you take your cutting. Pick a healthy stem tip that has about three or four buds on it and make a 6-inch cutting. Cut quickly and evenly to take the healthiest cutting possible.
- Add potting medium to your pot, and give it some water, ensuring that it has good drainage. Make a hole with your pencil in the medium, about two inches down. Dip your cutting in rooting hormone and place it in the hole. Fill in soil around it. Pat down just enough so the cutting stands up by itself. Give it some water.
- Keep the soil around your plant somewhat moist as it grows, and ensure that it is in a place that gets bright indirect light and stays at a temperature of between 50-60 degrees Fahrenheit. Once the danger of frost has passed the next spring, you can transplant your cutting to its final home outdoors.
Problems and Pests
Pentas, or Starflower, plants are susceptible to developing issues with the following pests and diseases in the landscape:
- Aphids
- Spider Mites
- Whiteflies
Gallery
Pentas flowers attract bees and butterflies, though they do not have a fragrance.
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These plants are considered to be low-maintenance.
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Here, a bed of Pentas is surrounded by a border of Buxus.
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This mixed bed features red-flowered Pentas and purple-foliaged Alternanthera.
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Pentas flowers do well in containers.
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Here, a Pentas plant is featured in a stone planter alongside Coleus and Astelia.
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Kalanchoe and Galphimia compliment white-flowering Pentas nicely.
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Pentas flowers can be deadheaded from time to time to clean up the plant and encourage more blooms.
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Pentas flowers have five points and are shaped like stars, hence the common name Star Flower.
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Videos
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All about Starflowers.
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An overview of these great garden ornamentals.
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Resources
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 492, Pentas lanceolata
