Mountain sandwort

Sun

Full sun in cool climates; light afternoon shade where summers are hot.

Water

Moderate; keep lightly moist while establishing, then water during prolonged dry spells. Avoid waterlogged soil, especially in winter.

Soil

Well-drained, gritty or sandy soil with modest fertility; tolerates acidic, neutral and alkaline conditions.

Height

0.25-0.5 ft (0.08-0.15 m)

Spread

1-1.5 ft (0.3-0.45 m)

Flowers

Late spring to early summer; white, five-petalled flowers with small yellow-green centres.

Foliage

Small, narrow, dark green leaves form a dense, low cushion. Usually evergreen, though foliage may suffer in severe winters.

Growth

Moderate

Care needed

Low

• Pollinators
• Deer resistant
• Cold hardy
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   0.1 ft (0.03 m)

2. After 1 year

   0.2 ft (0.06 m)

3. After 2 years

   0.3 ft (0.1 m)

4. After 3 years

   0.4 ft (0.12 m)

   full size

About 3 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Safe

Growth rate

Moderate

• Plant with the crown at soil level in a freely draining position.
• Water regularly through the first growing season, allowing the surface to dry slightly between waterings.
• Water established plants during extended drought, without leaving the root zone saturated.
• Avoid rich feeding; use a light spring application of balanced fertiliser only if growth is weak.
• Use a thin gravel mulch around the crown rather than moisture-holding organic mulch.

Pruning. Lightly shear after flowering to remove spent blooms and keep the cushion compact. In spring, trim away dead or winter-damaged shoots without cutting deeply into bare, woody growth.

Spring

Plant in gritty, well-drained soil and water thoroughly.

Spring

Remove winter-damaged shoots and clear fallen leaves from the cushion.

Late spring

Check soil moisture during flowering, particularly in pots and raised beds.

Early summer

Lightly shear after the main flowering flush.

Summer

Take non-flowering shoot cuttings and water established plants during prolonged drought.

Autumn

Check drainage and remove debris that could trap moisture around the crown.

• Plant between rocks in a rock garden, where the white flowers soften stone edges.
• Let cushions spill over the front of a raised bed or low retaining wall.
• Use along sunny path edges where plants will not be stepped on.
• Combine with compact pinks and creeping phlox for a low spring-flowering display.
• Grow in alpine troughs with other small plants that need sharp drainage.

Garden styles it suits: Alpine rock garden, Mountain lodge, Dry gravel garden, Cottage garden, White garden and Small-space.

Plant it with: Creeping phlox, Alpine pinks, Purple rock cress, Candytuft, Creeping thyme and Dwarf bearded iris.

Wildlife: The open flowers provide pollen and nectar for small bees and other visiting insects.

• Crown and root rot in wet soil: improve drainage, keep the crown clear of organic mulch and replace badly affected plants.
• Summer dieback in hot, humid conditions: provide afternoon shade and good airflow; avoid persistently wet soil.
• Slugs and snails damaging young growth: remove hiding places, hand-pick at dusk or use labelled iron-phosphate bait.
• Thin or bare centres in older cushions: take cuttings to raise replacement plants rather than cutting hard into old growth.

Not known to be toxic to people, cats, dogs or horses. Species-specific toxicity information is limited, and it is not an edible plant; discourage pets and children from eating it.

• Snow-in-summer (Cerastium tomentosum)

  Has conspicuously silvery, woolly foliage and deeply notched white petals; mountain sandwort has green foliage and petals that are not deeply split.

• Irish moss (Sagina subulata)

  Forms a much finer, moss-like carpet with tiny needle-like leaves and much smaller white flowers.

Arenaria comes from the Latin arena, meaning sand, referring to the sandy habitats of many members of the genus; montana means mountain-dwelling.

Propagation. Take short, non-flowering shoot cuttings in summer and root them in a gritty propagation mix. Sow seed in spring; seedlings may vary if seed comes from a named cultivar.

Accepted botanical name

Arenaria montana

Native range

France, Morocco, Portugal and Spain.

Measured

Average height 20 cm.

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