Sandwort (Arenaria) is a genus of low-growing perennials. These plants are known for their mat-forming habit, creating a dense carpet of foliage. Their compact growth and delicate flowers make them an effective ground cover.
Why Sandwort Excels as Ground Cover
Sandwort excels as ground cover due to several beneficial characteristics. Its dense growth suppresses weeds, reducing garden maintenance. Many varieties are drought-tolerant once established, contributing to their low maintenance needs. Sandwort also offers aesthetic appeal with fine-textured foliage and small, often white, star-shaped flowers in spring or early summer. It is well-suited for various landscaping purposes, including filling spaces between pavers, adorning rock gardens, or covering slopes to prevent soil erosion.
Popular Sandwort Varieties for Ground Cover
Several sandwort species are commonly cultivated for their ground-covering qualities. Arenaria montana, known as Mountain Sandwort, forms lush, evergreen cushions of small, glossy green leaves. This variety produces relatively large, pure white flowers in late spring to early summer. Mountain Sandwort is hardy and thrives in well-drained, sandy soils.
Another popular choice is Sagina subulata, commonly called Irish Moss. This plant forms a dense, emerald-green mat of foliage that closely resembles moss. Tiny, star-shaped white flowers emerge in spring. It tolerates light foot traffic, making it ideal for planting between stepping stones or as a lawn substitute. Arenaria verna, also referred to as Spring Sandwort or Scotch Moss, is another mat-forming perennial with small, star-shaped white flowers that bloom in clusters. While similar in appearance to Irish Moss, Arenaria verna typically has more yellow-green foliage and clusters its flowers, distinguishing it from Sagina subulata.
Planting and Care for Sandwort Ground Cover
Proper site selection is key for sandwort establishment. Most sandwort varieties prefer full sun to partial shade, tolerating partial shade in hotter climates. Mountain Sandwort thrives in full sun, requiring at least six hours of direct sunlight daily for optimal blooming, though it can tolerate partial shade. Well-drained soil is important, as sandwort naturally thrives in sandy, rocky, or gritty conditions. An ideal soil pH is generally between 6 and 7.
Before planting, prepare the area by breaking up the soil to a depth of 12-16 inches. Incorporate organic matter such as compost or peat moss, along with sand or perlite, to improve drainage and aeration. This creates a loose, workable soil structure that prevents waterlogging. When planting, space sandwort plants 6 to 12 inches apart to allow for their spreading habit. Gently remove the plant from its container, loosen the roots if dense, and set it at the same level as it was in the pot, then firm the soil around the root ball to remove air pockets.
Watering is crucial during the establishment phase; sandwort benefits from consistent moisture without being waterlogged. Once established, many sandwort varieties are drought-tolerant, but perform best with regular watering during dry periods. Mountain Sandwort, for instance, may require extra water during prolonged dry spells due to its shallow root system. Fertilization requirements are minimal; sandwort often performs well in poor, infertile soil. If desired, a general-purpose, balanced fertilizer can be applied in early spring, but over-fertilizing can lead to excessive foliage growth rather than a dense, mat-like form.
Pruning involves trimming as needed to maintain a neat appearance or encourage denser growth by snipping spent flowers or straggly stems. While sandwort is robust, good air circulation helps prevent fungal diseases. For winter care, leave foliage through colder months and cut it back in early spring before new growth emerges. In colder climates, mulching provides additional protection, though many sandwort types are hardy to USDA Zones 4-8.