Blankets of sparkling small white blooms from late spring to early summer give this tough perennial groundcover its name. After the blooms fade, the plant’s wooly silver foliage remains; it can handle some of the toughest droughts and is hardy in Zones 3-10. However, careful pruning and maintenance are needed to control this sometimes weedy plant.
I. Appearance and Characteristics
Cerastium tomentosum (snow-in-summer) is an herbaceous flowering plant and a member of the family Caryophyllaceae. It is generally distinguished from other species of its genus by “tomentose” or felty foliage. It is a low, spreading perennial native to alpine regions of Europe.It is native to southern Italy. It is believed to originate from the Caucasus and southeastern Europe. It has naturalized in Canada, the United States and France, where it is often sub spontaneous.
Snow-in-summer is also known as Cerastium tomentosum. It gets its common name from the prolific white blooms that look like blankets of snow in the summer. The genus name, cerastium, is related to the Greek word, keras. Keras means horn. The seed capsules in this genus are typically shaped like a cow’s horn, giving the genus its name. On the other hand, the specific epithet, tomentosum, is related to the word tomentose, which describes the felt-like, hairy foliage.
It is an evergreen, creeping off-shoot, perennial, herbaceous plant that reaches heights of growth of 15 to 30 (rarely to 45) centimeters. It is overall densely hairy. The leaves are up to 30 millimeters long and linear to lanceolate, which are covered with silky, silvery, frizzy and entangled hairs, forming like whitish felting. The inflorescences consist of up to 15 flowers. The calyx is 5 to 7 millimeters long. The petals are white and twice as long as the calyx. The teeth of the capsule are slightly bent outwards. The flowering period is from May to July in the northern hemisphere, but may also bloom at other times of the year.
It has proven popular as a cultivated ornamental and can be found in gardens the world over. It is a horticultural plant, perennial, rocky, forming dense silver carpets. This plant is not very demanding: it likes poor soil, rich in gravel, well drained, in a sunny place. It spreads easily by its rhizomes.
II. How to Grow and Care
Sunlight
Snow-in-summer grows at its best in areas where it can enjoy all the warmth and light of our beloved sun. Make sure you are growing your plant in a location with plenty of bright and direct sunlight. In general, Snow-in-summer may encounter fungal issues if it does not grow in full sunlight, so you should avoid keeping it in shady conditions.
Temperature and Humidity
In terms of temperatures, Snow-in-summer is super hardy and does best in the USDA zones 3 through 7. This plant prefers relatively dry and cool summer climates. Moreover, it will do just fine in cold temperatures during the winter. As a rule, Snow-in-summer will not live as much in areas that come along with hot and humid weather overall.
Cerastium tomentosum can have difficulties in handling too much shade or high humidity levels. When the plant experiences these particular conditions, it becomes more susceptible to fungal diseases like damping-off or root rot. You can easily avoid these unpleasant situations by growing your plant in well-draining soil and also a drier region.
Watering
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.
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.
Fertilizing
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 phosphorus, right before your plant blooms, might do the job. For the amount to use, follow the product label instructions.
Planting Instructions
Plant snow-in-summer from seedlings in early spring or start seeds indoors about 4 to 6 weeks before the last frost. Dig a hole slightly larger than the plant’s growing container and just deep enough that the plant will be able to sit at the same height in the ground as it did in its pot. If you are planting more than one plant, space them about 12 to 24 inches apart to prevent overcrowding.
If you are concerned about it spreading to other parts of your yard, add some in-ground landscape edging to a depth of about 5 to 6 inches around your snow-in summer plants to keep them corralled.
Pruning
Pruning is crucial to controlling the spread of snow-in-summer. One way to prevent the spread is to remove spent blooms (and any potential seeds) right after the plant flowers. In addition, because snow-in-summer typically finishes flowering all at once, you can trim back the whole plant at one time. Regular trimming also keeps the foliage compact instead of long and leggy. Snow-in-summer spreads by runners, too, so keep them trimmed to prevent unwanted growth.
Propagation
Snow-in-summer can be divided and replanted to create new plants. Division is best done immediately after the plants have finished blooming.
- Lift the entire plant out of the ground with a shovel.
- Divide it in half or more sections using pruners or a spade.
- 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 from Seed
It is also easy to grow snow-in-summer from seed. Simply sow the seed directly into your flower beds 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.
Pests and Diseases
This plant type doesn’t have severe disease or pest problems and is deer resistant and rabbit resistant.
If the snow in summer is placed under a well-shaded location or in a high humidity climate, it will start damping off.
Similarly, if this plant is grown in prolonged wet soils or poor soil drainage, it might experience a severe rotting issue.
Cerastium Tomentosum is often a short-lived plant, which means dead patches start emerging after a few years.
The snow plant is invasive and spreads well beyond the garden space intended.
Ideally, the spread of this plant is control by utilizing border edging which should be dug about 3” – 5” inches below the soil surface.
III. 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
IV. Uses and Benefits
This plant is used as ground cover in sunny areas.
It is a horticultural plant, perennial, rocky, mat-forming dense silver carpets.
It looks stunning when used as a bulb cover, edgings, in cottage gardens, border fronts, rock gardens, or dry stone walls.
It is ideally used in landscape design and is famous as border plantings.
It is also used for cascading over walls and banks to enhance the beauty of the garden.
Even before blooming, the silver-grey foliage of this plant looks stunning among other plants.
