The ice plants or delospermas are members of the Aizoon family. These are native to South Africa as well as central and east Africa. Though few are in cultivation, there are 150 or so species of ice plants.
Several of these are grown as hardy perennials, while others can be grown indoors as house plants. Hardiness can vary somewhat, depending on the species. These can be evergreen or semi-evergreen. The ice plants include as well as succulent shrubs. Some of the ones grown as perennials develop annual shoots from their tuberous caudex.
Ice plants have opposite, fleshy leaves. These can vary in shape from cylindrical to three-sided. The blossoms look much like those of the daisy. They are borne in open, flat topped heads or singly. When grown as house plants, these can bloom year-round.
The seeds typically take about two to three weeks to germinate at around 60 to 70 degrees Fahrenheit. However, in cases they have taken as long as two months. Often, they will bloom the very first year the seeds are planted. Sow these on the surface of the potting mix. Keep the soil moist until the seedlings emerge.
After the seedlings are transplanted into the garden, they will need watered occasionally until they’re well established.
Gardeners can buy seeds of a number of different ice plants. Thompson and Morgan sells seeds of Delosperma floribunda Stardust. Only four to six inches in height, this is recommended for zones six through eight. It has purplish-white blooms with clear white centers. The foliage is dark green.
Seeds of Delosperma John Proffitt is also available. This is called the table mountain ice plant. It is recommended for zones four through nine. John Proffitt ice plant has magenta blooms with white centers. It is only two to three inches tall.
Seeds of Delosperma lydenbergense is also available. This perennial reaches about six to eight inches in height. Its leaves are somewhat larger than those of most other ice plants. This species is native to South Africa.
For outdoor landscapes, plant these in full sun in a very well drained soil. They need a dry winter rest. Fertilize about once a month during the growing season.
At least four species of perennial ice plants are in cultivation. Delosperma cooperi is recommended for zones eight through ten.
One of the most commonly grown ones is Delosperma rubigenum, which is hardy to zone six. Delosperma ecklonis is recommended for zones three through nine.