Ice plant, or Delosperma, is a succulent plant that thrives in arid and rocky areas. In warm climates, ice plants are perennial and remain evergreen. In cooler areas, plants become semi-evergreen or die out completely and are replaced as an annual. Gardeners use ground cover sedums more often, although the ice plant blooms from May until September.
Ice plants are native to South Africa and the islands off the coast. Extremely adaptable, delosperma species grow at sea level and on mountain outcrops, and are abundant in South Africa's Eastern Cape. According to Plantzafrica, delosperma species are also found on the Arabian Peninsula and Madagascar. Ice plants are non-native but present in Asia and the United States, primarily in California. Cultivated varieties grow in European and North American gardens, especially in warm climates where the ice plant is reliably hardy.
According to the Flora of North America, 163 species of Delosperma exist. Of these, only a handful are available commercially. Delosperma cooperi with its succulent leaves and magenta flowers is one of the most familiar to gardeners. Delosperma floribundum Starburst is a hybrid with a touch of white in its magenta center. Lesser-known varieties of ice plant range in color from the white Delosperma alba to the fuchsia John Profitt to the peach-colored Mesa Verde. The hardiest ice plant is Delosperma nubigenum, a yellow type with tight, ground-hugging foliage.
Ice plants in the perennial garden are ground covers that add long-lasting color throughout the season. In the rock garden, they add a succulent texture that complements the terrain. Container planting is another venue to showcase the long-blooming nature of the plant. Some ice plant species have a utilitarian use. Colorado State University recommends the yellow ice plant for its fire resistance in areas prone to wildfires. The water-conserving nature of the ice plant benefits xeriscapes and green roofs.
Ice plants prefer well-drained soil in a sunny location. In keeping with their succulent nature, delosperma varieties, with the exception of the yellow ice plant, prefer very little water during the growing season, according to the Missouri Botanical Garden. Plantzafrica's recommendation is to mimic the the ice plant's South African habitat which receives summer rainfall. Gardeners may need to experiment to find the right watering schedule to keep the plants at their best. Fertilizer isn't crucial for ice plants, but a dilute nitrogen fertilizer applied in the spring can boost the plants' vigor. Delosperma varieties are hardy in USDA Hardiness Zones 6 to 10, although the Missouri Botanical Garden reports that ice plants in areas cooler than Zone 7 often do not survive the winter.
Propagation is accomplished by seed, division and cuttings. Spread the seed on the surface of moist soil and keep warm. According to the University of Maryland Cooperative Extension, germination takes approximately three weeks. Divide by lifting the entire clump and gently separating the plant in half with a knife or by hand. Cuttings of 3 to 4 inches root easily by dipping the stems in rooting hormone and placing them in a seed-starting planting mix.