Moss phlox

Moss phlox: how do you recognise it?

Habit

Low, creeping mat 10–15 cm tall and up to 50 cm wide, with trailing, slightly woody stems.

Leaves

Narrow, needle-like and stiff, 1–2 cm long, densely packed; evergreen.

Flower

Starry flowers with five petals, often notched at the tip and with a darker eye, in April–May.

Colour

Pink, lilac, pale blue, purple, red or white, sometimes striped.

Roots

Shallow. Trailing stems often root where they touch the ground.

Flowering: April–May · Plants: March–April and September–October · Pruning: June

Why grow it?

• A lavish spring display in April and May, like a colourful carpet.
• Evergreen: the mat stays green and dense through winter.
• A good ground cover that smothers weeds in sunny, dry spots.
• Bees and butterflies find nectar in the flowers in early spring.
• Ideal for walls, rock gardens, edges and pots: it spills attractively over the rim.

Moss phlox: where does it grow best?

• Full sun: in shade it flowers less and the mat becomes open and lax.
• Well-drained sandy or loamy soil, acid to neutral; not too chalky.
• Dry to moist. It cannot stand wet soil, especially in winter.
• Plant 40 cm apart, 5–6 plants per m², or between the stones of a wall or rock garden.

Light

Sun

Soil type

Sand or loam

Acidity

Acid or neutral

Moisture

Dry or normal

Size

0.15 m tall, 0.5 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Aubrieta: Flowers at the same time and tumbles just as prettily over a wall, in purple and blue.
• Rock cress: White cushions that soften the pink and purple tones.
• Golden alyssum: Bright yellow flowers as a contrast in the rock garden.
• Stonecrop: Low and drought tolerant, flowering in summer when the phlox has finished.
• Grape hyacinth: Blue flower spikes that push up through the mat.

Moss phlox: when and how to plant it?

Plant in March–April and September–October.

1. Plant in March–April or in September–October.
2. Loosen the soil, lighten heavy soil with coarse sand or fine gravel and carefully remove perennial weed roots.
3. Set the plant at the same depth as in the pot, not deeper: a buried crown rots easily.
4. In a wall: push the root ball with some soil into a gap and fill up with sandy soil.
5. Water in straight away and keep the soil slightly moist for the first weeks. Weed until the mat has closed.

Care

Water

Once established, only in long dry spells. In pots and walls it dries out faster.

Feeding

Not needed. On very poor sand you can add a thin layer of compost in March.

Weeding

Keep weeds out until the mat has closed; after that it suppresses them itself.

Clearing leaves

Remove fallen leaves from the mat in autumn: it rots underneath them.

Rejuvenating

If the centre goes bare, cut a young piece from the edge and replant it.

Tip: Trim lightly straight after flowering, by about a third: the mat stays dense and compact. Clear fallen leaves in autumn, as it rots underneath them.

Moss phlox: when to prune it?

Pruning months: June.

When: In June, straight after flowering. Otherwise no pruning is needed.

How:

• Trim the mat lightly with shears, by about a third, just below the faded flowers.
• This keeps the plant compact and reduces bare patches.
• Do not cut deep into bare, woody stems: they are slow to regrow.
• Cut dead patches out of the mat and fill the gaps with some sandy soil.

Caution: Do not prune in autumn or spring: you would remove the buds for the next flowering.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Cuttings

In June–July, after flowering: 5 cm cuttings from non-flowering shoots, in sandy cutting compost. They root within a few weeks.

Division

In March–April or in September: cut a rooted piece from the mat and plant it elsewhere. Trailing stems often already have roots.

Layering

Pin a long stem to the ground and cover it with a little soil; after a few months you can sever it.

Moss phlox: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, to about −30 °C: no protection is needed in Belgium.
• The leaves stay on in winter. Wet soil is the biggest danger, not frost.
• In a pot or trough: make sure drainage is good and do not leave the pot standing in a saucer of water.

Diseases and pests

• Rotting: Brown, limp patches, often after a wet winter or under fallen leaves. Provide free-draining soil and keep the mat clear of leaves.
• Bare patches: Older mats go bare in the centre. Trim after flowering and rejuvenate by division or cuttings.
• Red spider mite: Dull, finely speckled leaves in hot, dry weather. Spray the plant with water and water in dry spells.
• Poor flowering: Usually too much shade or too much feeding. Move it to full sun and do not feed.

Through the year

• March: Plant. Weed. Some compost on poor sand.
• April: Flowering. Plant.
• May: In full flower, a carpet of blooms.
• June: Trim lightly after flowering. Take cuttings.
• July: Water in long dry spells, especially in pots.
• September: Plant or divide off pieces.
• October: Plant.
• November: Clear fallen leaves from the mat.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Butterflies

Nectar for butterflies.

Did you know?

• Phlox is Greek for ‘flame’, after the bright flower colours. Subulata means ‘awl-shaped’, after the narrow, pointed leaves.
• It is also called moss pink, because outside flowering time the mat looks like moss.
• In Japan it is called shibazakura, ‘lawn cherry blossom’. Large fields of moss phlox draw many visitors there in spring, including at the foot of Mount Fuji.