How to Grow and Care for Snow-in-Summer

Snow-in-summer (Cerastium tomentosum) 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, a member of the carnation family, is just as admired for its delicate, woolly, silver leaves as for its charming flowers. These 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 favorable conditions.

Moderate-growing snow-in-summer makes an excellent ground cover for dry, sunny areas. It is deer resistant and often used in rock gardens or as a cover to fill in after spring bulbs are finished. It also can be used to fill pockets in stone walls.

Snow-in-Summer Care

Snow-in-summer is a perennial flowering groundcover that performs superbly well along the coast of the U.S. state of Maine. This fact suggests that the plant is reasonably salt-tolerant and enjoys the cooling Atlantic breeze that moderate summertime temperatures. These plants spread quickly, so space them at least 1 foot apart to stave off overcrowding.

After they have dumped their "snowfall" of white blooms in early summer, trim away the faded blooms and some of the foliage to keep the plants looking attractive for the rest of the summer. Snow-in-summer is grown as much for the glorious silvery carpet of foliage as for their attractive flowers.

To avoid rampant spreading, shear the flower stems off before seeds can be dropped. Trimming can be done easily with a lawnmower set high or with a string trimmer. Then, carefully clean up what you've cut away to prevent it from reseeding. Some cultivars are more compact and less likely to spread uncontrollably.

Light

This plant prefers full sun conditions. In the shade, snow-in-summer can develop fungal problems. You can avoid this by giving it the light it needs.

Soil

Snow-in-summer thrives in well-draining soil, preferring it slightly acidic (pH 6.0 to 7.0). But the plant adapts to most soil types except those that are damp and poorly draining, which can cause root rot.

Water

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

Snow-in-summer is suitable for growing in USDA hardiness zones 3 to 7. This is a plant that likes relatively cool, dry summers. It will be very short-lived if planted in hot, humid climates.

Fertilizer

This plant generally does not need any type of special feeding; it prefers rather poor soils. If you feel your snow-in-summer isn't performing the way you'd hoped, a fertilizer that's high in phosphorous, right before your plant blooms, might do the job. For the amount to use, follow the product label instructions.

Varieties of Snow-in-Summer

• 'Silver Carpet': features a more compact flowerhead and is slower spreading
• 'Yo Yo': produces abundant blooms
• 'Columnae': boasts features similar to 'Silver Carpet' but it is a lower-growing plant, forming 4-inch mounds
• 'Olympia': grows in clumps 6 to 8 inches tall and up to 18 inches wide with upright flower stalks

Propagating Snow-in-Summer

Snow-in-summer can be divided and replanted to create new plants. Division is best done immediately after the plants have finished blooming.

1. Lift the entire plant out of the ground with a shovel.
2. Divide it in half or more sections using pruners or a spade. 
3. Replant each section in a new location and keep it well-watered until you see new growth in a few weeks.

Self-seeded volunteers can also be dug up and transplanted. Newly germinated seedlings should be planted in early spring.

How to Grow Snow-in-Summer From Seed

It is also easy to grow snow-in-summer from seed. Simply sow the seed directly into your flowerbeds in early spring, and loosely cover with about 1/8-inch garden or potting soil. Germination should occur in two to three weeks. New plants won't bloom until their second year.

Common Pests and 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. Keeping your snow-in-summer in a drier area, with well-draining soil, will solve these problems.