Moss phlox

Sun

Full sun; light afternoon shade can help in hot summers, but too much shade reduces flowering.

Water

Water regularly while establishing, then only during prolonged dry spells. Avoid persistently damp soil, especially in winter.

Soil

Very well-drained, gritty or sandy soil with low to moderate fertility; tolerates slightly acidic through alkaline conditions.

Height

0.2-0.4 ft (0.06-0.12 m)

Spread

1-1.5 ft (0.3-0.45 m)

Flowers

Mid- to late spring; small, five-petalled flowers in pink, lavender, purple or white, depending on the selection.

Foliage

Evergreen. Tiny, stiff, narrow green leaves packed closely along short stems; foliage may bronze or brown in severe winter weather.

Growth

Slow to moderate, forming a gradually widening cushion.

Care needed

Low

• Pollinators
• Deer resistant
• Drought tolerant
• Cold hardy
• Low allergen

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

Difficulty

Easy

Toughness

Very tough

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

1. Planting day

   0.1 ft (0.02 m)

2. After 1 year

   0.1 ft (0.04 m)

3. After 2 years

   0.2 ft (0.06 m)

4. After 3 years

   0.3 ft (0.08 m)

5. After 5 years

   0.3 ft (0.09 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

Native to

the US and Canada

Growth rate

Slow

• Plant with the crown at soil level in a sunny position with sharp drainage.
• Water at the base during establishment, letting the soil begin to dry between waterings.
• Avoid rich manure and heavy feeding; use a light spring feed only if growth is weak on very poor soil.
• Use a thin gravel mulch rather than moisture-holding mulch against the cushion.
• Remove weeds by hand before they become rooted through the mat.

Pruning. Immediately after flowering, lightly shear off spent flowers and straggly green tips to keep the cushion compact. Avoid cutting deeply into old, leafless stems, which may not regrow.

Early spring

Remove dead foliage and check that winter rain has not left the crown sitting in wet soil.

Spring

Plant into free-draining soil and water until roots establish.

Late spring

Trim lightly after flowering to remove spent blooms and tidy the cushion.

Summer

Water during prolonged drought and check hot, dry plants for spider mites.

Summer

Take short, non-flowering shoot cuttings for new plants.

Autumn

Clear fallen leaves from the foliage and keep drainage channels open before winter.

• Plant between rocks in a sunny alpine garden for compact cushions and concentrated spring colour.
• Set along the top of a low retaining wall so the flowering edges spill slightly over the stone.
• Edge gravel paths with small groups, keeping plants clear of foot traffic.
• Combine with dwarf bulbs and other low alpines in a trough with generous drainage holes.

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

Plant it with: Rock cress, Candytuft, Sea thrift, Dwarf bearded iris, Species tulips and Low-growing stonecrops.

Wildlife: Spring flowers provide nectar for visiting bees and butterflies. The low cushions offer some shelter for small invertebrates.

• Crown or root rot in wet soil: improve drainage, keep mulch away from the crown and replace badly affected plants in a drier position.
• Spider mites in hot, dry weather: look for fine stippling and webbing; rinse foliage thoroughly in the morning and use insecticidal soap if needed, following the label.
• Sparse flowering and loose growth in shade: move to a sunnier position and avoid excessive nitrogen feeding.
• Brown or bare centres as cushions age: remove dead material and raise replacement plants from healthy shoot cuttings.

Not known to be toxic to people, cats, dogs or horses. No part is recognised as poisonous, but it is an ornamental plant rather than a food crop.

• Creeping phlox (Phlox subulata)

  Usually makes a broader, looser carpet with longer, needle-like leaves; Phlox douglasii generally forms tighter, lower cushions with shorter leaves.

• Woodland creeping phlox (Phlox stolonifera)

  Has broader, oval to spoon-shaped leaves and flower stems held distinctly above a creeping mat; it prefers more shade and moisture.

Phlox comes from the Greek word for flame, referring to flower colour in the genus, while douglasii honours the Scottish plant collector David Douglas.

Propagation. Take short, non-flowering shoot cuttings in summer and root them in a gritty, freely draining mix. Seed is possible, but named selections may not come true from seed.

Accepted botanical name

Phlox douglasii

In the US and Canada

Native in Canada and the lower 48 states.

Native range

British Columbia, California, Oregon and Washington.

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