Oncoba routledgei is a shrub or small tree native to Tropical Africa with dark green crenate leaves that are up to 5 inches (13 cm) long by half as wide. They have small spines that are ¾ to 1 inch (2-2.5 cm) long. In nature they will reach approximately 20 feet (~6.5 m) in height, but in containers their size is easily controlled with selective pruning and keeping the root volume small. They are hardy in USDA zone 10.
Blooming Time: In the greenhouse, the solitary, white flowers appear in spring. Flowers are up to 2 inches (5 cm) across and are mildly fragrant.
Culture: Oncoba routledgei need full sun to partial shade with a rich well-drained soil mix. In the greenhouse, we grow ours under 25% shade all year long. We use a soil mix consisting of 2 parts peat moss to 2 parts loam to 1 part sand or perlite. To this mix, we add 14-14-14 osmocote slow release fertilizer at a rate of 2 tbs (5 ml) per gallon (3.7 L) of pot size. During the growing season the plants are kept moist for optimum growth and fertilized with a balanced fertilizer on a weekly basis. During the winter months, the temperatures are dropped to 50° F (10° C) and water is restricted to about once a week or enough to keep the leaves from dropping.
Propagation: Oncoba routledgei are propagated by cutting or by seed in spring. Cutting are slow to root, so patience is needed. Seeds germinate in 21-30 days at 72° F (22° C).
Oncoba routledgei was featured as Plant of the Week May 16-22, 2003.
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. ©1998-2012 All rights reserved.