Haworthia retusa (Star Cactus)

Scientific Name

Haworthia retusa (L.) Duval

Common Names

Star Cactus, Window Succulent

Synonyms

Aloe retusa, Apicra retusa, Catevala retusa, Haworthia retusa var. retusa

Scientific Classification

Family: Asphodelaceae
Subfamily: Asphodeloideae
Tribe: Aloeae
Genus: Haworthia

Origin

This species is native to South Africa (a small area around Riversdale in the Western Cape Province).

Description

Haworthia retusa is a small succulent that forms star-shaped rosettes, up to 6 inches (15 cm) in diameter, of fleshy, lime green leaves with triangular translucent tips marked with longitudinal lines. In the wild, it is usually a solitary rosette, while in cultivation, it can offset and even form a clump of rosettes. Leaves are deltoid, recurved, up to up to 3.2 inches (8 cm) long, and up to 0.8 inches (2 cm) wide. Flowers are small, tubular, white with greenish-brown veins and appear in late spring to summer on unbranched, up to 20 inches (50 cm) long flower-stalks.

The specific epithet "retusa" derives from the Latin word "retusus," meaning "blunt or having a rounded apex" and refers to the "retused" leaf-shape (curved back like a thumb).

How to Grow and Care for Haworthia retusa

Light: Although some species can grow in full sun, most Haworthias are adapted to thrive in partial shade. Place the potted H. retusa in a bright area with some protection from the hottest rays of the day.

Soil: All Haworthias do not like their roots to remain wet for prolonged periods, so their potting soil should be well-drained. Use a commercial succulent potting mix or make your own.

Hardiness: Haworthias like warmer temperatures in the summer but cool in the winter. However, they do not like being too cold. H. retusa can withstand temperatures as low as 30 to 50 °F (-1.1 to 10 °C), USDA hardiness zones 10a to 11b.

Watering: During the hottest summer months, when Haworthias are mostly dormant, water just enough to keep the leaves from shriveling. From fall to spring, when growth is most active, water H. retusa thoroughly, then wait until the top of the soil dries out before watering again. Water the plants less during the winter when their growth slows down significantly.

Fertilizing: Haworthias do not require much fertilizer but for optimum growth, fertilization is a good idea. Feed only with a dilute fertilizer and only during the active growing season.

Repotting: These succulents are generally slow-growing and can stay in the same pot for years. For best health, H. retusa should be repotted into fresh soil every two to three years.

Propagation: Vegetative propagation, especially by offsets, is the quickest and most common method of propagating Haworthias. They can also be propagated by leaves and seeds. Remove the offsets when they have started developing their own roots. Sow seeds in spring or fall in a well-draining soil mix.

Learn more at How to Grow and Care for Haworthia.