Cerastium biebersteinii

Cerastium biebersteinii, also known as Mouse Ears or Boreal Chickweed, is a ground covering perennial with spreading stems which forms a fluffy grey carpet. Its soft foliage consists of evergreen narrow leaves. From May to July, depending on the region, countless small white flowers appear, transforming the plant into a carpet of snow. It is an ideal plant for covering large areas in poor and dry soil.

Mouse Ears is a very hardy plant native to Crimea. It has a spreading habit and creeping vegetation that allows it to quickly colonise an almost unlimited surface. It will not exceed 15 cm (6in) in height. Its fluffy mouse-grey foliage consists of small leaves, slightly larger than those of Cerastium tomentosum, the commonly encountered 'Snow-in-Summer'. Its growth is even more vigorous. Countless small white flowers appear from April-May, hiding the foliage beneath them.

Mouse Ears prefers a dry and sunny site. Plant it in dry to moist, light, and well-drained soil, ideally in a rocky and limestone substrate, preferably in September so that it has time to establish itself before the frosts arrive. It is a drought-tolerant plant and is sensitive to waterlogged soils. Use hedge shears to cut back the clumps to 5 cm (2in) above the ground in March.

Place Cerastium biebersteinii at the top of walls, or in the gaps between their stones. Ideal for a rockery, but also alongside steps, accompanied by e.g. thymes or dwarf artemisias. It also pairs well on a slope with other perennials and bushy plants for dry soil (lavenders, cistus, rosemary, brooms, leadwort, valerian), which it will allow to emerge through its foliage while protecting them from adventive plants. It is perfect for cultivation in pots on terraces and balconies, escaping to drape itself down their sides. Its use in green roofs is highly recommended.