Delosperma congestum, commonly known as Ice Plant, is a resilient and visually appealing evergreen succulent groundcover. It is valued for its low-maintenance nature, drought tolerance, and the vibrant display of its yellow flowers.
Characteristics and Identification
Delosperma congestum is characterized by its succulent, cylindrical leaves that often develop a reddish or maroon tint in cooler weather, particularly during winter. The common name “Ice Plant” originates from the crystalline appearance on its foliage, which reflects light, giving the leaves a frost-covered look. This plant forms a dense, mat-forming, and spreading groundcover, typically reaching a height of only 1 to 2 inches, though flowers can extend to 3 inches. It can spread between 8 inches to 2 feet wide.
During the summer months, Delosperma congestum produces a profusion of bright, golden yellow, daisy-like flowers that are about 1 inch across. These blossoms are so numerous they often completely cover the foliage. Originating from the dry alpine regions of South Africa and Lesotho, this species is surprisingly hardy in USDA Zones 4 to 10.
Growing and Care Guide
Light
Delosperma congestum thrives in full sun, requiring at least six to eight hours of direct sunlight daily for optimal growth and flowering. While it can tolerate partial shade, particularly in extremely hot climates, full sun exposure promotes the most prolific blooming.
Soil
Well-draining soil is crucial for Delosperma congestum, as it is intolerant of wet conditions, especially during winter. Sandy, gritty, or gravelly soil types are ideal, and the plant can even tolerate lean or poor soils. If the existing soil is heavy, incorporating coarse sand, pumice, or perlite can improve drainage. A pH range between 5.8 to 6.2 is generally suitable.
Watering
Once established, Delosperma congestum is highly drought-tolerant. During the growing season in spring and summer, deep but infrequent watering is recommended, allowing the soil to dry completely between waterings. Overwatering can lead to root rot, so it is better to err on the side of under-watering. In fall, watering should be reduced, allowing the plant to dry out in preparation for colder weather.
Temperature and Humidity
This ice plant exhibits notable cold hardiness, performing well in USDA Zones 4 through 10. It withstands temperatures down to around -20°F (-28.9°C); however, reliability can vary in colder, wetter climates. The plant is also heat and salt tolerant, making it suitable for a variety of conditions. In regions with consistent snow cover, covering the plants can help keep foliage dry and protect them.
Fertilizing
Delosperma congestum generally does not require extensive fertilization. If desired, a very light application of a balanced, slow-release fertilizer can be given once at the beginning of the growing season in spring. Excessive fertilization, especially late in the season, can lead to lush growth that is more susceptible to winter damage.
Planting
The best time to plant Delosperma congestum is during milder weather, such as mid to late spring after the soil has warmed. For warmer climates, planting can also occur in the fall. When planting, dig a hole that is slightly wider and as deep as the root ball, ensuring the top of the root ball is level with the surrounding soil. For groundcover, space plants about 8 to 12 inches apart.
Propagation and Maintenance
Propagation
Delosperma congestum is relatively easy to propagate, primarily through stem cuttings or division. For stem cuttings, select a healthy, non-flowering stem about 3 to 4 inches long. Remove the leaves from the bottom inch or two and allow the cut end to form a callus before planting in a well-draining succulent potting mix. Cuttings can be taken anytime from spring to fall.
Division is another effective method, best performed in spring. Carefully dig up a mature plant, then use a sharp tool to divide the root ball into sections. Each section should have some roots and foliage. Seeds can also be used for propagation; they should be scattered on the soil surface and not covered, as they require light to germinate.
Maintenance
Delosperma congestum is a low-maintenance plant. Minimal pruning is needed, primarily to maintain shape, remove spent flowers, or clear any winter-damaged foliage in mid-spring. The plant resists most pests and diseases when grown in appropriate conditions. Occasional weeding may be necessary if used as a groundcover.
Common Uses and Benefits
Delosperma congestum is versatile in landscaping due to its spreading habit and vibrant blooms. It excels as a groundcover, forming a dense mat that can help suppress weeds. Its low-growing nature makes it suitable for rock gardens, gravel gardens, and alpine settings, where it can spill over edges and fill crevices.
The plant is an excellent choice for xeriscaping and water-wise gardens due to its exceptional drought tolerance. It performs well on slopes and banks, providing erosion control. Delosperma congestum can also be effectively used in containers, where its trailing habit creates an beautiful display. The bright yellow flowers attract pollinators like bees and butterflies, contributing to garden biodiversity.