🌻 Introduction

Delosperma cooperi is a spreading succulent ground cover forming dense mats 10-15 cm tall and up to 60 cm wide, producing an abundance of glistening magenta-purple daisy-like flowers 3-5 cm across from June through October. Native to the high-altitude grasslands of Lesotho and the Eastern Cape of South Africa at 1,800-2,700 m, it is one of the hardiest ice plants, tolerating temperatures to -20°C when planted in sharply drained soil.

Stems are fleshy, succulent, creeping and rooting at nodes, green to reddish, forming a dense interlocking mat. Leaves are opposite, cylindrical to slightly flattened, 3-5 cm long and 4-6 mm in diameter, bright green with glistening papillae (bladder cells) covering the surface that sparkle in sunlight like ice crystals. Flowers are solitary on short peduncles, 3-5 cm in diameter, with numerous narrow ray-like petals (actually staminodes) in vivid magenta-purple radiating from a central boss of yellow stamens and white stigmas. The capsule is a hygroscopic structure that opens when wet to release tiny brown seeds, closing again when dry.

Quick Facts

🔍 Identification Guide

The glistening bladder cells on the cylindrical fleshy leaves that sparkle like ice give this plant its common name and are diagnostic. The vivid magenta-purple flowers with yellow staminal centres and the spreading succulent mat habit distinguish it from all other hardy perennials. Delosperma nubigenum has yellow flowers and smaller, more tightly packed leaves. D. congestum has yellow flowers and forms denser cushions. The long flowering period (June-October) is unusual among hardy succulents and helps with identification during the growing season.

Flower Anatomy

Detailed Morphology

The flower is built on the typical Aizoaceae plan with numerous petaloid staminodes in 2-4 whorls, creating the daisy-like appearance. True petals are absent. Fertile stamens are numerous (50-100), yellow, arranged in a central cone. The stigmas number 5-8, white, radiating between the stamens. The ovary is inferior, developing into a 5-8 chambered hygroscopic capsule 8-10 mm across that opens its valves when wetted, allowing raindrops to splash seeds up to 1 m from the parent. The bladder cells (epidermal vesicles) store water and salts, contributing to frost tolerance by acting as sacrificial freezing sites.

🧬 Taxonomy & Classification

Delosperma cooperi belongs to Aizoaceae (formerly Mesembryanthemaceae), the ice plant family containing approximately 1,800 species predominantly in southern Africa. The genus Delosperma contains about 170 species. D. cooperi is placed in the section with cylindrical leaves and was described by L. Bolus in 1927. Molecular phylogenetics confirms the genus is monophyletic. Several species previously sold as D. cooperi may be D. sutherlandii or hybrids. Chromosome number is 2n = 18. The species hybridises readily with other Delosperma species in cultivation.

🐝 Bloom & Pollinators

Flowering begins in June and continues until the first hard frost, with individual flowers lasting 5-7 days and opening only in direct sunlight. The flower closes at night and on overcast days, protecting the pollen and stigma from moisture. Peak bloom occurs in July-August. The hygrochastic capsule opens only when wet, ensuring seed dispersal coincides with conditions favourable for germination. Seeds are tiny (0.5-0.8 mm) and require light for germination. In its native Lesotho habitat, flowering coincides with the summer rainfall season (November-February in the Southern Hemisphere).

Pollinator Relationships

Pollinated primarily by bees and various flies attracted to the vivid magenta colour and accessible pollen. In its native South African range, monkey beetles (Hopliini) are important pollinators that burrow into the staminal cone for pollen, inadvertently transferring it between flowers. In European and American gardens, honeybees and bumblebees are the main visitors. The flower produces no nectar; pollen is the sole reward. Butterflies visit for basking on the warm flower surface but contribute minimally to pollination.

Bloom Details

🔎 Similar Species

Delosperma nubigenum has yellow flowers and more compact growth, forming dense cushions only 3-5 cm tall. D. congestum (Hardy Yellow Ice Plant) has golden-yellow flowers and denser, more compact rosettes. Lampranthus species are similar South African succulents but are generally frost-tender and have larger, showier flowers. Drosanthemum species have similar glistening leaves but are tender perennials in most temperate climates. Aptenia cordifolia (Heartleaf Ice Plant) has heart-shaped leaves and smaller magenta flowers.

Known Look-Alikes

🌍 Native Range & Habitat

Native to the Drakensberg escarpment of Lesotho and the Eastern Cape province of South Africa at 1,800-2,700 m elevation. Grows in montane grassland on well-drained rocky slopes and cliff ledges where winter temperatures regularly drop to -15°C. The high altitude ensures dry winters with snow cover providing insulation, and wet summers when the plant actively grows and flowers. Annual rainfall in its native range is 700-1,000 mm, concentrated in summer months. Associated with Helichrysum, Euryops, and Kniphofia in high-altitude grassland communities.

Range & Habitat

🗺 Distribution Map

Native distribution of Hardy Ice Plant / Cooper's Ice Plant (range: South Africa (Lesotho, Eastern Cape highlands)). It has been introduced in North America, Mediterranean Europe.

🌱 Growing from Seed

Sow seed on the surface of moist, gritty compost in spring at 18-22°C, pressing lightly without covering as seeds need light. Germination occurs in 14-21 days with rates of 50-70%. Seedlings are tiny and grow slowly for the first 2 months; keep moist but not wet. Transplant to individual pots when 2 cm across. Stem cuttings taken in summer are much faster, rooting in 7-10 days in damp perlite with nearly 100% success. Plants from cuttings flower in the first season; seedlings typically flower in year two.

Propagation Methods

• Stem cuttings
• Seed
• Division

Seed Starting Guide

🏡 Garden Cultivation

Requires full sun and extremely well-drained soil; amend heavy soils with 50% coarse grit or grow in raised beds and containers with mineral-based substrates. Hardy to USDA zones 5-10 when drainage is perfect; winter wet kills more plants than cold. Drought-tolerant once established, requiring no supplemental irrigation in most climates. No fertiliser needed; rich soil promotes soft growth susceptible to rot. Space 25-30 cm apart for full coverage within one growing season. Ideal for green roofs with 5-8 cm substrate depth.

Site Requirements

Additional Traits

• Salt tolerant — suitable for coastal gardens

🤝 Companion Planting

Combine with Sedum acre, Sempervivum tectorum, and Thymus serpyllum for a low-maintenance succulent rock garden carpet. The magenta flowers contrast strikingly with the yellow of Sedum acre and silver foliage of Cerastium tomentosum. Plant with Armeria pseudarmeria and Dianthus deltoides for a long-season colour display. Use as ground cover beneath taller rock garden plants like Penstemon and Lavandula where the mat can spread without competition from vigorous growers.

Recommended Companion Plants

🦋 Wildlife Value

Provides pollen for bees from June through October, filling a late-season gap when many other rock garden plants have finished flowering. Butterflies use the warm flower surfaces for thermoregulation in cool autumn weather. The dense mat shelters small invertebrates including ground beetles, spiders, and centipedes. In South Africa, the succulent leaves are browsed by rock hyraxes and various rodents. Seeds are consumed by small granivorous birds. The plant provides minimal food value in European gardens but contributes structurally to ground-level habitats.

Wildlife Interactions

• Nectar and pollen for bees

🌿 Conservation

Listed as Least Concern in South Africa where it remains common in montane grasslands. Overgrazing by livestock in Lesotho has reduced populations in some accessible valleys, but the species persists on rocky outcrops and cliff ledges beyond the reach of cattle. Climate change threatens the high-altitude grassland habitat as temperatures increase and the frost line moves upward. The species is widely cultivated globally and not at risk of genetic erosion. No wild collection for the horticultural trade occurs, as vegetative propagation is easy and fast.

📅 Seasonal Interest

Spring growth emerges from the overwintered mat in April, with bright green succulent leaves expanding rapidly. Flowering begins in June and continues through October, providing 4-5 months of vivid colour. Autumn frost turns the foliage bronze-red to purple, an attractive colour change persisting through early winter. Severe winter cold (-15°C and below) causes the aerial parts to shrivel and brown, but the root system survives to resprout in spring. In mild winters (zones 8-9), foliage remains green year-round.

🏨 Landscape Design

Excellent ground cover for hot, dry, sunny banks and slopes where erosion control is needed. Plant in rock garden pockets, along gravel path edges, and cascading over retaining walls. Ideal for extensive green roof installations with minimal substrate depth. Use in parking strip plantings and other zero-irrigation challenging sites. Space 25-30 cm apart in groups of 5-7 for rapid coverage. The long bloom season makes it valuable in combination with spring- and autumn-flowering plants to maintain continuous colour. Avoid shaded or north-facing positions.

Design Considerations

• Growth form (Spreading mat-forming succulent ground cover) determines placement in borders and naturalistic plantings
• At 10-15 cm, consider position relative to sight lines and companion heights
• Allow 30-60 cm spacing for natural spread
• Low-maintenance choice for naturalistic or xeriscape plantings

🏷️ Varieties & Cultivars

The 'Table Mountain' series from Denver Botanic Gardens trials includes deep magenta forms selected for exceptional cold hardiness to -25°C. 'Kelaidis' (Mesa Verde) is a salmon-pink hybrid of uncertain parentage. 'Fire Spinner' has bicoloured orange-and-pink flowers, likely a hybrid with D. dyeri. 'Jewel of Desert' series from the Netherlands offers garnet, topaz, and moonstone colour forms. 'White Wonder' is a white-flowered selection. 'Gold Nugget' has yellow flowers and may involve D. congestum parentage.

📜 Folklore & Ethnobotany

The Basotho people of Lesotho have no documented ethnobotanical use for D. cooperi, though other Delosperma species are used medicinally in southern African traditional medicine. Named for Thomas Cooper, a 19th-century English botanist who collected plants in South Africa. The common name 'ice plant' derives from the glistening epidermal bladder cells that resemble ice crystals, not from any cold-tolerance association. Introduced to European horticulture in the early 20th century but only became widely popular after cold-hardiness trials in the 1980s at Denver Botanic Gardens.

Traditional & Ethnobotanical Uses

• No significant ethnobotanical uses
• One of the hardiest ice plants

Medicinal & Herbal Uses

No traditional medicinal use is documented for D. cooperi specifically. Other Delosperma species in southern African traditional medicine are used as topical treatments for skin infections and burns, with the succulent leaf gel applied directly. The plant contains mesembrine-related alkaloids in trace amounts, which are psychoactive compounds found in higher concentrations in related genera (Sceletium). The succulent leaves have mild emollient properties when broken open. Not used in Western herbal medicine.

💡 Beginner's Guide

Plant in the sunniest, best-drained spot available; this species absolutely refuses to tolerate shade or wet feet. Improve heavy soil by mixing in 50% coarse grit before planting. Water newly planted specimens weekly for the first month, then stop watering entirely. Take cuttings in summer as insurance against winter loss; stick 5 cm stem tips in damp perlite on a windowsill. In zones 5-6, mulch lightly with gravel (not organic mulch) and ensure the planting site slopes for winter drainage. Replace any winter-killed patches with rooted cuttings in spring.

Common Mistakes to Avoid

Growing Tips

Troubleshooting

Winter death is almost always caused by wet soil rather than cold; ensure rapid drainage and avoid low-lying frost pockets where water collects. Plants that survive winter but look brown and shrivelled will usually regenerate from the roots; do not remove them until late May. Mealybugs colonise the leaf bases in greenhouse culture; treat with rubbing alcohol on a cotton swab. Scale insects on stems are controlled with neem oil. Slugs and snails generally avoid the succulent foliage but may eat young growth in wet springs.

❓ Frequently Asked Questions