Woodland phlox

Woodland phlox: how do you recognise it?

Habit

Low, loose clump about 30 cm tall and 40 cm wide. The creeping stems root where they touch the soil.

Leaves

Narrowly oval to lance-shaped, 3–5 cm long, opposite, dark green and slightly hairy.

Flower

Loose clusters at the stem tips. Each flower is 2–3 cm across, with a narrow tube and five flat petals, often slightly notched.

Colour

Lavender-blue to lilac; white or pale blue in some cultivars.

Scent

Sweet and clear, best noticed on a mild, still day.

Roots

Fine and fairly shallow: the plant dries out quickly in a dry summer.

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

Why grow it?

• Scented flowers from April to June, just as the spring bulbs fade.
• One of the few phloxes that really thrive in half shade and light shade.
• Attracts bees and especially butterflies, whose long tongues reach the nectar in the narrow flower tube.
• Low and loose: ideal for the edge of a shade border, under shrubs or between ferns.
• Fully hardy and low-maintenance: one cut back after flowering is enough.

Woodland phlox: where does it grow best?

• Half shade or light shade, for example under deciduous trees and shrubs. In full sun it dries out and easily gets powdery mildew.
• Humus-rich loam or clay, acid to neutral.
• Moisture-retentive but not boggy: do not let it dry out in summer, and avoid standing water in winter.
• Plant 30–40 cm apart; it looks best in a small group of three to five plants.

Light

Partial shade and shade

Soil type

Loam or clay

Acidity

Acid or neutral

Moisture

Normal

Size

0.3 m tall, 0.4 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Ferns: Fresh green fronds beside the blue flowers, in the same moist half shade.
• Barrenwort: Flowers at about the same time and covers the ground with elegant leaves.
• Siberian bugloss: Small sky-blue flowers and large heart-shaped leaves in shade.
• Foamflower: White flower spikes in spring, also a plant of North American woodland edges.
• Hosta: Large leaves that take over once the phlox has finished flowering.

Woodland phlox: when and how to plant it?

Plant in March–April and September–October.

1. Plant in March–April or in September–October, when the soil is not frozen or waterlogged.
2. Loosen the soil and work in a few spadefuls of leaf mould or well-rotted compost.
3. Dig a hole slightly larger than the root ball and set the plant at the same depth as it was in the pot.
4. Leave 30–40 cm between plants.
5. Firm the soil and water in well straight away.
6. Spread a thin layer of leaf mould or fine mulch around the plants.

Care

Water

In the first year, water regularly in dry spells. After that only in long dry periods, at the base and not over the leaves.

Feeding

A thin layer of compost in March or April is enough. Too much fertiliser gives floppy stems.

Mulching

A layer of leaf mould in spring or autumn keeps the soil cool, moist and rich in humus, like a woodland floor.

Spent flowers

After flowering, cut back the faded flower stems; leave the low shoots in place.

Rejuvenating

If the clump becomes bare in the centre after a few years, divide it and replant the young pieces from the edge.

Tip: Plant it under deciduous shrubs or trees: in spring it gets enough light there to flower, and in summer the leaf canopy keeps the soil cool and moist.

Woodland phlox: when to prune it?

Pruning months: June.

When: After flowering, in June. Otherwise it needs hardly any pruning.

How:

• Cut the faded flower stems back to just above the foliage or the creeping shoots.
• Leave the low, non-flowering shoots: next spring’s flower stems grow from them.
• In March, remove dead stems or stems damaged by winter.
• Cut out stems with powdery mildew straight away and put them in the household waste, not on the compost heap.

Caution: Do not cut it right down in autumn: the flower stems grow in spring from the shoots that overwinter.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

After flowering or in September, lift a rooted piece from the clump and replant it straight away elsewhere. Water well.

Layering

The creeping stems often root by themselves. Cut off a rooted piece and replant it.

Cuttings

In May–June, take 5–8 cm cuttings from non-flowering shoots and insert them in moist cutting compost, in good light but out of strong sun.

Woodland phlox: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, to about −30 °C: no protection is needed in Belgium.
• Wet feet in winter are a greater risk than frost: make sure excess water can drain away.
• A layer of leaf mould in autumn protects the shallow roots and feeds the soil.
• In a pot: stand it against a wall so the root ball does not stay frozen for long.

Diseases and pests

• Powdery mildew: White powder on the leaves, especially in dry weather and in too sunny a spot. Water, space plants well and cut out affected stems.
• Slugs: Eat young shoots in spring. Pick them off in the evening or after rain.
• Aphids: On young shoots and flower buds. Hose them off with a strong jet of water; ladybirds and hoverflies do the rest.
• Stem eelworm: Swollen, distorted stems and narrow, crinkled leaves. Remove affected plants completely and do not plant phlox in that spot for a few years.
• Poor growth: On dry, poor soil or in full sun it dwindles. Move it to half shade and add compost.

Through the year

• March: Plant. Remove dead stems. Add compost.
• April: Flowering starts. Watch for slugs and aphids.
• May: Full flower and scent. Take cuttings from non-flowering shoots.
• June: Last flowers. Cut back the faded stems.
• July: Water in dry spells. Watch for powdery mildew.
• August: Water in dry spells.
• September: Plant and divide.
• October: Plant. Mulch with leaf mould.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Butterflies

Nectar for butterflies.

Did you know?

• The name Phlox comes from the Greek word for flame, after the bright flower colours of many species.
• ‘Divaricata’ means spreading widely and refers to its loose, broadly branching growth.
• The nectar lies deep in a narrow flower tube, so mainly butterflies and other long-tongued insects can reach it.