What is Cerastium?

Cerastium is a perennial genus of flowering plants known by common names such as mouse-ear chickweed or simply chickweed. It is estimated that there are approximately 100 species in this genus, several of which are cultivated as ornamental plants in various regions of the world. People interested in growing a Cerastium can access seedlings or divisions through nurseries, other gardeners, and plant catalogs. Members of this genus are hardy and very easy to grow.

These plants are groundcovers, with a spreading growth habit. They put out runners to propagate themselves and tend to stay low to the ground, producing small silvery to green foliage, often with hairs, and profuse white flowers. The tiny flowers typically appear in spring and can last through the summer, depending on the species and the settings. Generally, Cerastium is not invasive, although it certainly will spread if provided with room to do so.

Climate requirements vary, depending on the species, with most species growing comfortably in United States Department of Agriculture (USDA) zones three through seven. Cerastium tends to prefer full sun and well-drained soil worked with sand. It can be very tolerant of poor soils. The plants do not do well in extreme heat, dryness, or humidity, and are subject to rot if they are kept in damp or wet conditions. Poorly drained soil will be a problem for these members of the pink family.

One species, C. tomentosum, known as “snow in summer,” is a popular choice among gardeners in some regions. It is named for the array of white flowers produced during the summer months. When it is not flowering, the silvery foliage can be very attractive. Like other members of the genus, it needs to be clipped or mowed at a high setting after it flowers to keep the plant tidy and prevent a matting growth habit. Matting can subject the plant to rot and cause bald patches to develop.

Members of this genus are ideally suited as groundcovers in areas where they have some room to spread. Rock walls, bare patches in the garden, and containers are all suitable spots for cultivating Cerastium. Clipping will help the plant keep its shape and remain tidy, and it can be a good choice for a location where people want low maintenance plants. Many species are drought tolerant, suitable for low-water gardens and xeriscaping, and the plants can be easily propagated by digging up existing plantings and dividing them.