Ice Plant, commonly referring to succulent groundcovers from genera like Delosperma and Lampranthus, is a popular choice for gardeners due to its vibrant, daisy-like flowers and exceptional drought tolerance. These low-growing perennials thrive in sunny, dry conditions where many other plants struggle. Gardeners often select this plant for its ability to quickly cover ground, but this fast-spreading nature raises questions about its speed and manageability. This article clarifies the biological mechanisms that drive this expansion and provides context on the speed and scale of its spread in a typical garden environment.
The Mechanism of Ice Plant Spread
The most significant way Ice Plant expands horizontally is through a process called stem rooting or layering. As the plant’s succulent, trailing stems or runners grow outward, they maintain contact with the soil surface. At the nodes along these stems, new roots readily develop, establishing a new, independent plantlet connected to the parent plant. This continuous anchoring and rooting process allows a single plant to form a dense, interconnected mat that steadily creeps across the landscape.
Another method of expansion for some varieties is through self-seeding, although this varies greatly depending on the species. While some popular cultivars are sterile, others generate seeds that can be dispersed by wind, water runoff, or small animals. These seeds are most likely to germinate in disturbed or bare soil, which is often prevalent in the dry environments Ice Plant prefers.
The plant’s succulent nature also contributes to its ease of spread through fragmentation, which can make manual removal challenging. If a stem is broken or cut during maintenance, the detached piece can often root easily in the soil. This ability for fragments to establish new growth means gardeners must be careful to remove all plant pieces when clearing unwanted areas.
Growth Habit and Aggressiveness
The speed at which Ice Plant spreads is directly related to the species planted and the local environmental conditions. Many garden-center varieties of Delosperma are valued for their manageable, mat-forming habit, providing dense coverage without becoming overly aggressive. Under ideal conditions—full sun, well-drained soil, and minimal water—most vigorous garden varieties can be expected to spread their diameter by approximately 1 to 2 feet per year.
The perception of “aggressiveness” often comes from species like the Highway Ice Plant, Carpobrotus edulis, which is known to be ecologically invasive in coastal regions, particularly in California. This invasive species forms thick, heavy mats that can choke out native flora and alter the soil’s composition. In contrast, the hardy Delosperma varieties typically sold for groundcover are fast-spreading but manageable in a contained garden setting.
Environmental factors are powerful drivers of the spread rate. A plant growing in nutrient-poor, sandy soil with plenty of sun will spread much faster than one in a shady, moist location. Soil moisture is a key factor, as the plant’s stems readily send out roots when they contact damp ground. An unstressed Ice Plant focuses its energy on rapid horizontal expansion to colonize the surrounding area and outcompete neighboring weeds.
Managing and Directing Ice Plant Growth
To keep the natural tendency of Ice Plant to spread within desirable boundaries, regular maintenance is necessary. The most effective technique is routine pruning or trimming of the outer edges, which prevents the runners from rooting into unwanted areas. Cutting back the perimeter growth controls the plant’s size and encourages denser, more compact growth toward the center.
Physical barriers can be used strategically to limit the plant’s spread and reduce the frequency of manual trimming. Installing shallow edging or planting the Ice Plant alongside hardscape features, such as concrete walkways or patios, prevents the stems from rooting into the adjacent soil. This method capitalizes on the plant’s need for soil contact to establish new root systems.
If complete removal of a section or an entire patch is required, manually pull up the growth and ensure all rooted stem fragments are cleared from the area. Because the plant’s roots are shallow, careful raking or hand-pulling can be effective for smaller areas. Any remaining stem pieces or cuttings left on the soil surface may re-root, requiring diligence during the removal process to prevent regrowth.