Haworthia retusa, or Star Cactus, is a native of the Cape Province of South Africa. It is a rosette forming plant with stubby, deltoid pale green leaves up to 2 inches (5 cm) long. The terminal area is translucent with pale lines. Individual plants reach up to 4 inches (10 cm) across. They are hardy in USDA zones 9 and 10. Of interest to botanists are the translucent windows that illuminate the interior photosynthetic areas of the leaves. These are called "window leaves" and represent a xerophytic adaptation.
Blooming Time: In late spring, the small white with green striped flowers appear. They are not particularly showy!
Culture: Haworthia retusa need full sun to light shade, warm temperatures and a well-drained soil mix. We use a soil mix consisting of 2 parts loam to 2 parts course sand. Allow the soil to dry between waterings in the growing season. Fertilize monthly with a balanced fertilizer diluted to ½ the strength recommended on the label. In the winter months, reduce watering and do not fertilize. The plants sucker freely and will soon fill up most pots. Repot only when the plant has outgrown its pot. Clay pots are best.
Propagation: Haworthia retusa are propagated by the removal of offshoots in spring.
Haworthia retusa was featured as Plant of the Week August 30-September 5, 2002.
Guide to Past Plants-of-the-Week:
Cal's Plant of the Week was provided as a service by the University of Oklahoma Department of Microbiology & Plant Biology and specifically the late Cal Lemke, who used to be OU's botany greenhouse grower and an avid gardener at home as well. If the above links don't work, then try the overview site. You may also like to look at the thumbnail index. ©1998-2017 All rights reserved.