How to Grow Cerastium
Cerastium tomentosum
Cerastium is a tough, low-growing evergreen groundcover forming dense silver-grey mats smothered in white starry flowers in early summer. It demands full sun and sharp drainage, thriving in poor, dry, stony soil where little else grows. Plant 30 cm apart in spring or autumn. Shear back hard after flowering to keep the mat dense and prevent bare centres. Extremely drought-tolerant and hardy once established, it needs almost no care but can spread aggressively in rich soil.
Yearly Lifecycle
Care Essentials
Rarely needed. Cerastium thrives in poor, lean soil. Excessive feeding causes leggy growth and reduces flowering.
Watch For
- Root rot in waterlogged soil
- Aphids on young growth
- Excessive spread into borders
Companions
Aubrieta, Sedum, Thyme, Dianthus
Care Requirements
Light
Full sun essential
Demands full sun and sharp drainage for best silver foliage and prolific flowering. In shade or rich moist soil it becomes leggy and invasive.
Watering
Extremely drought-tolerant
Needs no supplementary watering once established. Thrives in dry, stony, poor soil. Overwatering or waterlogging causes root rot and death.
Fertilizing
Never feed
Thrives in poor, lean soil. Excessive feeding causes leggy growth, reduces flowering, and makes the mat loose and floppy rather than compact.
Pruning
Shear hard after flowering
Shear the entire mat back by half after flowering finishes. This prevents bare centres, maintains the compact silver effect, and keeps the plant vigorous.
