Snow-in-summer is a perennial flower that gets its common name from its blooming habit. It blooms profusely in the early summer with a blanket of notched pristine white flowers that suggest a fresh snowfall. But the name does not tell the whole story. This ground cover is just as admired for its delicate, woolly, silver leaves as for its charming flowers. The narrow grayish-green leaves spread a mat of foliage from which flower stems rise in late spring/early summer. Snow-in-summer spreads quickly by reseeding and by producing runners when grown in conditions favorable.
Snow-in-summer makes an excellent ground cover for dry, sunny areas. It is often used in rock gardens or as a cover to fill in after spring bulbs are finished. It also can be used to fill in pockets in stone walls.
|Botanical Name||Cerastium tomentosum|
|Plant Type||Herbaceous perennial|
|Mature Size||6 to12 inches tall; 9- to 12-inch spread|
|Sun Exposure||Full sun|
|Soil Type||Dry, sandy, well-drained soil|
|Soil pH||6.0 to 7.0|
|Hardiness Zones||3 to 7 (USDA)|
|Native Area||Italy, Sicily|
How to Grow Snow-in-Summer
Snow-in-summer plants prefer full sun and thrive in well-drained, poor soil. Having a site with good drainage is a must for growing them successfully. These perennial flowers perform superbly well along the coast of Maine (United States). This fact suggests that they are reasonably salt-tolerant and that they enjoy the cooling breezes coming off the Atlantic, which moderate summertime temperatures.
This plant spreads quickly, so plant them at least 1 foot apart. To avoid rampant spreading, shear the flower stems off after flowering is complete and before seeds can be dropped. Some cultivars are more compact and less likely to spread uncontrollably.
This plant prefers full sun conditions. It can develop fungal problems in shady locations.
Snow-in-summer adapts to most soil types, except for damp, poorly drained soils, which can cause root rot.
This plant prefers relatively dry conditions and has a good tolerance for short periods of drought. It will not do well where frequent rainfall or watering keeps the ground soggy.
Temperature and Humidity
While snow-in-summer is suitable for growing in USDA hardiness zones 3 to 8, though it is sometimes grown in zones 9 and 10 in areas where summer temperatures are mild and not too humid. This is a plant that likes relatively cool, dry summers, and it will be very short-lived in hot, humid areas. High humidity can create damping-off disease and other fungal problems with this plant.
This plant generally does not need feeding; it prefers rather poor soils.
After they have dumped their "snowfall" of white blooms in early summer, trim away the faded blooms and some of the foliage to keep snow-in-summer plants looking attractive all summer. Remember, they are grown as much for the silvery carpet of the foliage as for their attractive flowers. Trimming can be done with a lawnmower set high, or with a string trimmer.
Where desired, the roots of snow-in-summer can be divided and replanted to create new plants. Division is best done immediately after the plants have concluded blooming. Self-seeded volunteers can also be dug up and transplanted.
Varieties of Snow-in-Summer
Although fussy if conditions aren't perfect, under the right circumstances, this plant can be somewhat aggressive in its spreading habit. Among the recommended cultivars that have been bred to have a more compact, slower growth habit:
- Cerastium tomentosum 'Silberteppich', known as 'Silver Carpet', is more compact and slower spreading.
- C. tomentosum 'YoYo' is also more compact and slower spreading. It produces abundant flowers.
- C. tomentosum ‘Silver Carpet’ has frosty, white foliage, is more compact and less aggressive than the species.
C. tomentosum 'Columnae' is similar to 'Silver Carpet' but it is a lower plant, forming 4-inch mounds.
Common Pests/ Diseases
High humidity or too much shade can foster damping-off disease and other fungal problems. Root rot can be a problem in soil that is too moist.
While considered fussy in some regions, in other areas, snow-in-summer has a reputation for being an invasive plant. Be careful to keep this plant in its boundaries and not allow it to naturalize into surrounding areas.