The common name “Ice Plant” refers to a group of succulent ground covers known for their bright, daisy-like flowers and foliage. Whether this plant can survive the winter depends entirely on the specific species planted and the regional climate where it is grown. For gardeners in cooler climates, successfully overwintering an ice plant is less about the low temperature itself and more about managing winter moisture and ensuring a dry, dormant period.
Identifying Hardy Versus Tender Varieties
The term “ice plant” generally covers two main genera of succulents, and distinguishing between them is the first step in determining winter survival. The most cold-tolerant varieties belong to the Delosperma genus, often called the Hardy Ice Plant, which is reliably perennial in USDA Zones 5 through 9. These hardy types, such as Delosperma cooperi, can typically withstand temperatures well below freezing, sometimes surviving down to -20°F. However, even these hardy varieties are highly susceptible to wet, cold conditions that cause root rot.
The second common group belongs to the Lampranthus genus, which is significantly more sensitive to cold. These are considered tender perennials and are generally only hardy in much warmer climates, typically USDA Zones 9 to 11. In any region with a consistent winter freeze, Lampranthus must be treated as an annual or brought indoors.
Essential Winter Preparation for Survival
Preparation must focus on creating the driest possible environment, as excessive moisture leads to crown and root rot when the plant is dormant. Planting ice plants in a location with excellent drainage is the most important factor for success. Ideal locations include slopes, rock gardens, or areas with sandy or gravelly soil. Dense clay or heavy loam soils should be avoided or significantly amended to improve aeration and water flow.
In the late summer and early fall, drastically reduce or entirely stop watering the plants. This cessation of moisture forces the succulent foliage to “harden off” and induces the necessary dormancy period. Avoid fertilizing in the fall, as this encourages soft, vulnerable new growth that is more likely to suffer cold damage.
Protecting Ice Plants from Extreme Cold and Moisture
For hardy varieties growing at the lower end of their tolerance range (Zone 5 or 6), physical protection is needed to shield them from prolonged wet conditions and extreme temperature drops. Applying a layer of dry, light mulch is beneficial, but it must be carefully chosen to prevent moisture retention. Materials such as small gravel, pine needles, or coarse bark chips work well when placed around the plant’s crown. This layer insulates the roots and keeps the stems and foliage from sitting in direct contact with wet soil.
During periods of heavy snow, freezing rain, or sudden cold, temporary covers can provide extra defense. A piece of row cover or a frost blanket placed over the plants prevents excessive moisture buildup on the foliage, which causes winter kill. For container-grown ice plants, which are susceptible to root freezing, move the pots to a sheltered, unheated location. This could be against a south-facing wall or inside a cool garage.