These tiny blooms have five petals which is the source of their name. Penta is the ancient Greek word for the nunber five. However, these flowers should always be called Pentas (either singular or plural). They are also known as Egyptian Star Flower, Star Flower, Egyptian Star Cluster, or simply, Star Cluster. From the Missouri Botanical Garden,
Winter hardy to USDA Zones 10-11 where it is easily grown in average, medium, well-drained soils in full sun. Tolerates part shade, but best flowering in full sun. Best in organically rich, fertile soils. In St. Louis, grow in the ground as bedding annuals that are replaced in the garden each spring or in pots/containers as frost-tender perennials that are overwintered indoors. May be easily grown from seed started indoors in late winter approximately 8-10 weeks before last frost date. During the growing season, water regularly (allow soils to dry somewhat between waterings) and feed monthly. To overwinter, bring pots/containers inside before first frost to a bright, cool (50s) location and reduce watering. Cuttings may also be taken from favorite plants in late summer for overwintering. Also may be grown as a houseplant in a sunny room with high humidity.
They are blooming in our garden now. However, ours did not form the large clusters that some plants develop. They are still quite pretty and the butterflies love them (as you can see in the photo below)!
For more information about these plants that butterflies love so much, visit the NOLA website.