Berkheya purpurea is a fast growing, long-lived perennial native to South Africa. Plants have a long taproot and form very tight rosettes of wavy, very spiny leaves. Leaves are somewhat shiny green above with the underneath side covered with soft white hairs. The leaves can reach up to 15 inches (40 cm) long and the plant forms very dense clumps. Care should be taken when handling these plants. Spines are very sharp and rigid. In nature, the plant grows along stream banks and on steep mountain slopes. These areas get summer rainfall and are subject to snow and frost in the winter months. They are very interesting plants to grow and are of fairly easy culture in container or in the landscape. Plants are hardy in USDA zones 6-10.
Blooming: In nature and in the greenhouse, Berkheya purpurea bloom in summer. The capitulum has irregular spiny wings and smaller leaves, and will reach up to 3 feet (1 m) in height. Flower buds are formed on the upper third of the floral stalk. Flowers are up to 3 inches (10 cm) across with pale to dark mauve ray flowers. Disk flowers are dark purple with interesting white pollen. I found the flowers to be mildly fragrant and very showy.
Culture: Berkheya purpurea needs full sun and a well drained soil mix. In the greenhouse, we used a soil mix consisting of 2 parts peat moss to 1 part loam to 2 parts sand. Plants are well watered and allowed to dry slightly before watering again. We fertilize the plants only once during the growing season with a balanced fertilizer diluted to 1/2 the strength recommended on the label. As a landscape planting, I suspect this plant would be very drought tolerant, more so than plants in containers. When working with these plants I would strongly suggest wearing leather gloves. Spines are very nasty. During the winter months, plants are moved to the cool rooms where the nighttime temperature is 48°F (9°C) and water is restricted, but not enough to cause injury to the plant. Some plants die back to ground level, but return in spring with very vigorous growth.
Propagation: Berkheya purpurea is propagated by hardwood and softwood cuttings in spring and from seed.
Berkheya purpurea was featured as Plant of the Week May 22-28, 2009.
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Cal's Plant of the Week was provided as a service by the University of Oklahoma Department of Microbiology & Plant Biology and specifically 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.