The term “ice plant” is the common name for a group of flowering, succulent groundcovers, primarily belonging to the genera Delosperma and Lampranthus. This name originates from the tiny, bladder-like hairs on the leaves of some species, which reflect light in a way that makes the foliage appear to shimmer like ice crystals or dew. These plants are valued in landscaping for their ability to thrive in harsh, dry environments while producing a profusion of vibrant, daisy-like flowers. Their low-growing, mat-forming habit makes them a popular choice for gardeners seeking color with minimal water use.
Key Characteristics and Main Varieties
Ice plants are native to the arid regions of Southern Africa, resulting in fleshy, succulent foliage designed to store water. The leaves are typically small, cylindrical, or triangular, forming dense, low mats that rarely exceed six inches in height. Their most notable feature is the showy, star-shaped flowers, which bloom in a wide spectrum of colors, including magenta, orange, yellow, pink, and bi-colors. These blooms open fully in bright sunlight and close up at night or on cloudy days.
The two most common genera are distinguished primarily by their cold tolerance. Delosperma, often called the hardy ice plant, includes species that can survive winter temperatures down to USDA Hardiness Zone 4, provided conditions are dry. Popular cultivars include Delosperma cooperi (magenta flowers) and ‘Fire Spinner’ (orange and purple combination). In contrast, Lampranthus species are generally more tender, suited for warmer climates in Zones 9 through 11, and often exhibit a more upright or trailing growth habit.
Essential Growing Conditions
Ice plants require full sun exposure, meaning a minimum of six hours of direct sunlight daily for prolific flowering. Insufficient light will cause the stems to stretch out, resulting in leggy, sparse growth and reduced bloom production.
The second requirement is excellent, fast-draining soil, as the plants are highly susceptible to root rot in constantly moist conditions. Ideal soil compositions are lean, sandy, or gravelly, allowing water to pass through quickly. Dense clay soil should be avoided or heavily amended with grit or perlite to improve drainage. Once established, ice plants require minimal supplemental water, thriving on deep watering only when the soil has completely dried out.
While many Delosperma varieties are cold-hardy, their survival in colder regions depends more on dryness than temperature. Wet, soggy soil during the winter months is damaging, as the combination of moisture and freezing temperatures destroys the roots. In areas with heavy winter snow or rain, ensuring the plants are situated on a slope or covered to maintain dry crowns is a practical measure for overwintering success.
Landscape Uses and Growth Management
Ice plants are widely used in landscaping for their ability to form a dense, colorful groundcover. Their drought tolerance makes them a preferred choice for xeriscaping, rock gardens, and planting on sunny slopes where other plants struggle. The trailing nature of some varieties also makes them suitable for cascading over retaining walls or spilling from containers.
Maintenance is minimal, typically involving only the removal of winter-killed or brown stems in the spring to encourage fresh growth. Gardeners should be aware of the plant’s vigorous, fast-spreading nature, which requires management. Certain species, such as Carpobrotus edulis (highway ice plant), are considered highly invasive in regions like coastal California. This species forms thick mats that can choke out native vegetation and alter soil composition. Choosing non-invasive, well-behaved cultivars, such as Delosperma hybrids, is necessary to prevent ecological issues.