Woodland phlox

Sun

Partial shade or bright, dappled shade. Morning sun is suitable in cool climates; avoid hot afternoon sun.

Water

Keep evenly moist while establishing and during spring growth. Water established plants during dry spells, especially beneath thirsty trees, without leaving the soil waterlogged.

Soil

Humus-rich, well-drained soil that holds some moisture; mildly acidic to neutral soil is ideal. Avoid dry sand and persistently wet clay.

Height

1-1.5 ft (0.3-0.45 m)

Spread

1-2 ft (0.3-0.6 m), gradually forming wider patches

Flowers

Mid- to late spring, sometimes into early summer in cool regions; pale blue, lavender-blue, violet or white, usually fragrant.

Foliage

Opposite, green, softly hairy, oval to lance-shaped leaves on creeping leafy shoots and upright flowering stems. Some basal foliage persists through mild winters.

Growth

Moderate

Care needed

Low

• Pollinators
• Cold hardy
• Low allergen
• Fragrant

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

   1 ft (0.3 m)

2. After 1 year

   1.1 ft (0.32 m)

3. After 2 years

   1.1 ft (0.35 m)

4. After 3 years

   1.2 ft (0.38 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

Moderate

• Water at soil level during dry spells; do not let newly planted roots dry out.
• Apply a thin layer of leaf mould or compost each spring; rich soil usually needs no additional fertiliser.
• Mulch with shredded leaves to conserve moisture, keeping mulch away from the crowns.
• Divide congested patches after flowering or in early autumn, and water divisions until established.
• Leave space around plants for airflow rather than packing them tightly against taller neighbours.

Pruning. After flowering, cut spent flower stems back to the leafy growth if you want a tidier patch or less self-seeding. Remove dead or diseased stems, but retain healthy low foliage.

Early spring

Remove dead stems and apply a thin layer of compost or leaf mould.

Spring

Plant into moist, prepared soil and water regularly while roots establish.

Late spring

After flowering, trim spent stems and divide patches if needed.

Summer

Water during prolonged dry weather and check foliage for powdery mildew.

Early autumn

Plant or divide while the soil is moist and there is time for roots to establish before winter.

Late autumn

Retain a light covering of fallen leaves, but remove thick, wet mats from the crowns.

• Plant in drifts beneath deciduous shrubs for a fragrant spring carpet before the canopy fills out.
• Edge shaded paths with small groups so the flowers and scent can be enjoyed close up.
• Combine with ferns and hostas, whose expanding foliage helps cover tired stems after flowering.
• Weave among spring bulbs and woodland perennials for overlapping flowers and contrasting leaf shapes.

Garden styles it suits: Woodland, Cottage garden, Wildlife garden, Pollinator garden, Romantic rose garden and Blues and silvers.

Plant it with: Ferns, Hostas, Foamflower, Virginia bluebells, Solomon's seal and Daffodils.

Wildlife: Flowers provide nectar for butterflies, moths and long-tongued bees. It is useful in spring woodland plantings, but deer and rabbits may browse it.

• Powdery mildew: improve airflow, avoid drought stress and remove badly affected foliage; water the soil rather than the leaves.
• Slugs and snails: protect young shoots with hand-picking or iron-phosphate bait used according to its label.
• Crown or root rot: improve drainage and avoid wet winter planting pockets; remove rotting plants.
• Scorched leaves or summer decline: provide afternoon shade and water during drought; foliage may thin naturally after flowering.

Not known to be toxic to cats, dogs, horses or people; no poisonous parts are recognised. It is not a food plant, and eating plant material can still cause stomach upset.

• Creeping woodland phlox (Phlox stolonifera)

  Forms a lower, denser mat with broader, rounded leaves on creeping shoots and generally shorter flower stems.

• Moss phlox (Phlox subulata)

  Has narrow, stiff, needle-like evergreen leaves and a dense cushion habit; it usually grows in sunny, freely drained sites.

• Dame's rocket (Hesperis matronalis)

  Has four petals per flower rather than five, alternate rather than opposite leaves, and much taller flowering stems.

Phlox comes from the Greek word for flame, while divaricata means spreading or widely branching, referring to the plant's branching habit.

Propagation. Divide rooted patches after flowering or in early autumn, or root non-flowering stem cuttings in late spring or early summer. Fresh seed can be sown outdoors in autumn; seedlings may differ from named cultivars.

Accepted botanical name

Phlox divaricata

In the US and Canada

Native in Canada and the lower 48 states.

Native range

Alabama, Arkansas, Connecticut, Delaware, District of Columbia, Florida, Georgia, Illinois, Indiana, Iowa, Kansas and Kentucky.

Measured

Soil pH 5.5 to 7.2. Average height 36 cm.

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