Common Name: Cape pondweed
Type: Herbaceous perennial
Native Range: Southern Africa
Zone: 6 to 10
Height: 0.50 to 4.00 feet
Spread: 1.00 to 2.50 feet
Bloom Time: July to September
Bloom Description: White
Sun: Full sun to part shade
Suggested Use: Water Plant, Rain Garden
Flower: Showy, Fragrant
In the St. Louis area, this aquatic perennial is best grown in relatively shallow areas of small ponds or water gardens where the water level is from 6-24” deep or in greenhouses. It may be grown in either the bottom mud or in containers placed on the bottom. This plant thrives in cool waters of 70F or less. When grown in warm winter climates (e.g., USDA Zone 9-10), plants will flower from fall to spring but go dormant in the heat of the summer. In colder winter climates, plants typically flower in summer and early fall, but die back in winter or must be brought indoors. Plants are perhaps best propagated from seed because the tubers can be difficult to divide. The seed must be kept in a wet medium (e.g., moss) from harvesting to planting. Seed is best planted as soon as it is matures in containers submerged in 3” of water. Use fertile loams with 1/ 2” sand sprinkled on top. Seed can also germinate directly on the water surface. In St. Louis (USDA Zone 6), plants may survive outdoors in winter if grown in protected water bodies where the water does not freeze over the crown. Plant containers may be brought inside for overwintering in a greenhouse or sunporch. In warm winter climates, plants can spread through self-seeding unless spent flowers are promptly removed.
Cape pondweed is a water lily-like plant that produces floating leaves and fragrant flowers from tubers growing at the bottom of water bodies. It is native to frost free areas of South Africa where it typically blooms in small ponds from fall to spring and then goes dormant in summer as the temperatures rise and the ponds dry up. In St. Louis, it will grow in full sun to part shade and appreciates a good loamy soil. Oblong leaves (to 3-6” long) lie flat on the water surface. Sweetly scented white flowers rise above the surface usually in the cooler months. Flowers reportedly have a hawthorn-like fragrance, hence the additional common name of water hawthorn. In South Africa, this plant is commercially grown for its edible tubers that may be added to stews.
No known serious insect or disease problems.
Water gardens, ponds or other small bodies of water. Greenhouses.