Delosperma cooperi
| Light | Full sun; the more the better for flowering and tight growth |
|---|---|
| Water | Moderate in growth; sparing in winter, keep quite dry when cold |
| Soil | Gritty, sharply draining mix (see Soil and potting mix) |
| Temperature | Root-hardy to around USDA zone 6 with excellent drainage |
| Propagation | Cuttings (very easy); division; seed |
| Toxicity | Non-toxic to cats and dogs |
Delosperma cooperi is the classic cold-hardy ice plant, a low, spreading succulent from South Africa that forms dense mats and covers itself in brilliant magenta-purple, daisy-like flowers right through the warm months. It is one of the few succulents that can be grown as a hardy garden groundcover in cold-winter climates, which — together with its long, dazzling bloom — has made it a landscaping and rock-garden favourite. It belongs to the ice-plant family Aizoaceae; for the wider group see Delosperma.
Description
Delosperma cooperi is a mat-forming, trailing perennial that stays low — generally under about 15 cm tall — but spreads outward to form broad cushions. Its cylindrical to slightly flattened leaves are fleshy, green and studded with tiny glistening bladder cells — the "ice" that gives the family its common name — which sparkle in bright light.
The flowers are the main event: shimmering, many-petalled, daisy-shaped blooms in a vivid magenta-purple with a paler centre, typically 3–5 cm across. They open in response to sunshine, closing in dull weather and at night, and appear in profusion from late spring through summer and often into autumn, so that a healthy plant can be almost hidden beneath colour. Despite the daisy resemblance the plant is not related to the true daisies; the flower structure is that of the Aizoaceae.
Distribution and habitat
The species is native to South Africa, where it grows on open, rocky and grassy ground at elevation. Because those wild habitats experience cold, dry winters rather than the mild, wet winters of many succulent regions, D. cooperi is markedly frost-tolerant — the trait that has made it so valuable in temperate gardens. In cultivation it is now widely grown across Europe, North America and beyond as a hardy groundcover.
Its hardiness depends heavily on drainage: the plant tolerates hard frost far better when its roots are dry, and is far more likely to be lost to a wet, cold winter than to cold alone.
Cultivation
Delosperma cooperi is one of the easiest succulents to grow well, provided two conditions are met — full sun and sharp drainage. Give it as much direct light as you can; in shade the mat grows loose and leggy and flowering drops off sharply. Plant it in a gritty, free-draining mix or a lean garden bed, ideally on a slope, raised bed or rockery where water never sits.
Through the growing season it appreciates more water than a typical desert cactus and will reward moderate watering with vigorous growth and heavy bloom; let the surface dry between waterings. As temperatures fall, cut water right back and keep the plant on the dry side — winter wet is the single biggest cause of loss. Where it is grown as a hardy groundcover, a covering of grit or gravel around the crowns helps shed moisture. It also grows happily in containers and hanging pots, where it trails attractively over the rim. A light trim after the main flush keeps mats dense and tidy; see Watering and Repotting for general technique.
Propagation
Propagation could hardly be simpler. Stem cuttings root quickly and reliably: take a trailing piece, let the cut end callus for a day or two, and lay or insert it on a gritty surface kept lightly moist. Established mats can also be lifted and divided, and the species comes readily from seed as well, though named colour selections are kept true by cuttings rather than seed.
Cultivars
D. cooperi and its close relatives have been selected and hybridised for a range of flower colours beyond the classic magenta — including forms marketed in pinks, oranges, yellows and bicolours — often sold under trade or series names. Care for these selections is as for the species. See Delosperma for an overview of the genus and its garden hybrids.
Common problems
- Rot — by far the commonest killer, caused by wet, cold or poorly drained soil, especially in winter; crowns and stems go soft and brown.
- Legginess and poor flowering — a sign of too little light; move to full sun and trim back to encourage dense growth.
- Winter loss — usually down to drainage rather than absolute cold; plants in heavy, damp soil may not survive a winter they would shrug off in gritty ground.
- Pests — generally trouble-free outdoors, but mealybugs and aphids can appear on soft growth, particularly on container plants (see Pests and diseases).
See also
- Delosperma — the genus overview
- Soil and potting mix · Watering · Propagation — cuttings · Propagation — seed · Pests and diseases