Snow-in-summer

Sun

Full sun; shade makes growth looser and reduces flowering.

Water

Water regularly while establishing, allowing the soil to dry between waterings. Established plants need little extra water except during prolonged drought.

Soil

Lean, sharply drained sandy, gritty or stony soil; tolerates neutral to alkaline conditions. Avoid heavy clay and wet winter ground.

Height

0.5-1 ft (0.15-0.3 m), including flower stems

Spread

1-2 ft (0.3-0.6 m), spreading farther over time

Flowers

Late spring to early summer; masses of small white flowers with five deeply notched petals.

Foliage

Small, narrow, grey-green leaves densely covered with silvery-white hairs; usually evergreen, but may become sparse or partly deciduous in severe winters.

Growth

Fast where conditions suit it; creeping stems root as they spread.

Care needed

Low

• Plant in full sun with sharp drainage; use a raised bed or slope if your soil stays wet.
• Water new plants at soil level, then reduce watering once their roots are established.
• Avoid routine feeding: rich soil encourages floppy growth and fewer flowers.
• Use a thin gravel mulch rather than moisture-holding organic mulch around the crowns.
• Pull out rooted stems that cross bed edges, and divide congested or bare-centred patches in spring.

Pruning. Shear off spent flowers and lightly shorten the leafy growth immediately after flowering to keep the mat compact and reduce self-seeding. Avoid cutting deeply into bare, woody centres.

Early spring

Remove winter-damaged growth and divide patches with bare or congested centres.

Spring

Plant into well-drained soil and water until established.

Late spring

Check the edges of flowering mats and remove stems spreading into neighbouring plants.

Early summer

Shear after flowering, before seed capsules mature.

Summer

Water established plants only during prolonged dry spells; check for dieback in humid weather.

Autumn

Clear fallen leaves from the mat and make sure winter rain can drain away.

• Let it spill over a sunny retaining wall, where its silver foliage softens the stone.
• Plant small patches among rocks or gravel for a low silver carpet with a brief white flowering display.
• Edge a sunny path with it, keeping the mat back from walking surfaces; it does not tolerate regular foot traffic.
• Pair it with purple-flowered lavender, catmint or low-growing thyme for contrast in a dry border.
• Use it around spring bulbs in a sharply drained bed, leaving enough space so it does not smother smaller plants.

Garden styles it suits: Cottage garden, Dry gravel garden, Alpine rock garden, White garden, Mediterranean and Coastal.

Plant it with: English lavender, Catmint, Creeping thyme, Sea thrift, Dianthus and Stonecrop.

Wildlife: The flowers provide pollen and nectar for visiting bees and other insects. It is not a native plant in the United States, Canada, the United Kingdom or Australia.

• Crown or root rot in wet soil: improve drainage, stop unnecessary watering and replace badly affected plants in a drier position.
• Summer dieback in hot, humid conditions: avoid overhead watering and crowded planting; choose another groundcover if this recurs.
• Bare centres and untidy growth: shear lightly after flowering and divide healthy outer sections in spring.
• Unwanted spread and seedlings: remove creeping stems promptly and cut off flowers before seed develops.

Not known to be toxic to cats, dogs, horses or people, and no particular part is recognised as poisonous. It is not an edible plant; eating plant material may still cause stomach upset.

Where it spreads. Can spread aggressively by rooting stems and seed in cool, well-drained gardens, including parts of the northern United States, southern Canada, the United Kingdom and southern Australia. It has escaped cultivation in these regions; contain it near natural areas and check local invasive-plant guidance before planting.

• Bieberstein's snow-in-summer (Cerastium biebersteinii)

  Very similar, but generally has larger, broader leaves and somewhat larger flowers. Nursery plants can be difficult to distinguish without close botanical examination.

• Evergreen candytuft (Iberis sempervirens)

  Has dark green, leathery leaves rather than silver felted foliage. Its white flowers have four unequal petals and form dense, flattened clusters.

• Creeping phlox (Phlox subulata)

  Has green, needle-like leaves rather than broad, woolly silver leaves. Its flowers have a conspicuous tubular base and may be white, pink, purple or blue.

Snow-in-summer describes the mass of white flowers; Cerastium refers to the horn-shaped seed capsules, and tomentosum means densely woolly, describing the leaves.

Propagation. Divide rooted sections in spring or take non-flowering shoot cuttings in summer. Seed can be sown in spring, but remove unwanted seedlings where spread is a concern.

Accepted botanical name

Cerastium tomentosum

In the US and Canada

Introduced in Alaska, Canada and the lower 48 states.

Native range

Italy and Sicilia.

Measured

Average height 15 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.