Haworthia retusa

The star cactus is small, perennial, succulent and is native of the Cape Provinces of South Africa. The plant is found in the semi-arid climate, growing in the shade of rocks or plants to protect itself from the sun. It is a member of the day lily family (Asphodelaceae). The specific epithet, retusa, is Latin for retusus that means "blunt" and refers to the plant's blunt leaf shape that curves backward like a thumb. 

This low maintenance plant prefers bright, indirect light. It can tolerate morning or late afternoon sun, but exposure to midday sun may cause leaf scorch. It requires well-drained succulent or cactus mix with added sand or perlite to encourage adequate drainage. The plant is drought tolerant, and overwatering may cause root rot. The potting medium should be allowed to dry out between waterings. Temperatures between 60 to 80 degrees Fahrenheit are ideal. It is hardy in USDA  zones 10 to 11 and needs to be protected from frost. The humidity in most homes is well-tolerated by the star cactus. It is propagated by removing the offsets or pups that form at the base of the parent plant. 

The star cactus is small, slow-growing, and has a compact habit in the form of a star-shaped rosette. It measures up to 3 to 6 inches tall and 4 to 6 inches wide. The leaves are thick, fleshy, glossy, triangular, lime green, and have transparent tapered tips that curve backwards. Its flowers are small, tubular, and may be white or pale pink and appear on slender stems that measure up to 20 inches tall. 

The star cactus is a slow-growing, ornamental, and is suitable for use as a houseplant, desk plant, or terrarium. 

Insects, Diseases, and Other Plant Problems: Monitor for mealybugs, spider mites, aphids, and fungus gnats. Excessive watering can cause root rot. Fungal diseases like powdery mildew can result from wet leaves or overly humid conditions. The plant is sensitive to frost. Leaf burn can result from intense direct sunlight. This plant is non-toxic, but the sap may cause skin irritation.

VIDEO Created by Elisabeth Meyer for "Houseplants, Succulents, and Cacti", a plant identification course offered in partnership with Longwood Gardens.

More information on Haworthia.