Snow-in-summer
Also known as
Woolly mouse-ear, Woolly chickweed, Woolly cerastium, Silver carpet
Keep this plant’s care guide close at hand.
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Cerastium tomentosum, commonly called snow-in-summer, is a low, mat-forming perennial in the carnation family (Caryophyllaceae) prized for its silvery, tomentose foliage and profuse, starry white flowers. Typically 10–15 cm tall, it spreads readily to form a dense, weed-suppressing carpet that cascades beautifully over walls and edging. In late spring to early summer, plants are smothered in bloom, creating a striking “snow” effect against gray-green leaves. Native to rocky, often calcareous slopes of southern and central Europe, it excels in lean, very well-drained soils and is notably drought-tolerant once established. Semi-evergreen in mild winters, it can thin or brown in hot, humid summers but rebounds when conditions cool. Its rapid spread makes it excellent for rock gardens, gravel beds, and sunny slopes, though occasional shearing after flowering keeps it compact and curbs self-seeding. Avoid overly rich or wet soils, which cause floppy growth and rot. Easy to grow, resilient, and low-maintenance, it provides long-lasting texture and a brilliant seasonal display.
Taxonomy
Properties & Requirements
How to care for Snow-in-summer
Water
Water newly planted mats regularly for the first 2–3 months to establish, allowing the top 2–3 cm of soil to dry between waterings. Once established, water deeply but infrequently—typically only during prolonged drought. Aim to wet the root zone and then allow the soil to dry well; constant moisture invites rot. Use drip or soaker hoses rather than overhead watering. In containers, increase frequency but maintain free drainage; never let pots sit in saucers of water.
Light
Full sun (6+ hours direct light) yields the tightest mats and heaviest bloom. In very hot summer regions, light afternoon shade can reduce stress but may slightly lessen flowering. Avoid deep shade, which leads to lanky growth and sparse flowers. Reflective heat from walls or paving is tolerated if the soil is gritty and fast-draining. Indoors is not recommended; this is an outdoor groundcover adapted to bright, open conditions.
Nutrients
Snow-in-summer is a light feeder adapted to lean, well-drained, often calcareous soils. Mix a small amount of compost or grit into the planting site, but avoid rich amendments. In the ground, skip regular fertilizer; excessive nitrogen causes lush, floppy growth and fewer flowers. Container-grown plants can receive a very dilute, balanced, low-nitrogen feed once in mid-spring. Favor calcium-rich substrates (crushed gravel or limestone chips) and maintain sharp drainage to prevent root rot.
Temperature
Hardy in cold climates (roughly USDA Zones 3–7/8), it tolerates severe frost yet dislikes persistent heat and humidity. Ideal growing temperatures are cool to mild, roughly 10–25°C. In regions exceeding 30–32°C for extended periods, provide afternoon shade, sharp drainage, and excellent air circulation. Protect from winter-wet: raised sites or sloped beds help crowns stay dry in cold, saturated soils. Semi-evergreen in mild winters; foliage may thin during hot summers but recovers with cooler weather.
