Phlox 'David'

Sun

Full sun to partial shade; afternoon shade helps in hot climates, but heavy shade reduces flowering.

Water

Keep the root zone evenly moist, especially during summer and while plants establish. Avoid prolonged drought and waterlogged soil.

Soil

Fertile, humus-rich, moisture-retentive but well-drained soil; tolerates mildly acidic to mildly alkaline conditions.

Height

3-4 ft (0.9-1.2 m)

Spread

2-3 ft (0.6-0.9 m)

Flowers

Midsummer to early autumn; fragrant, pure white, five-petalled flowers in large terminal clusters.

Foliage

Opposite pairs of pointed, lance-shaped green leaves on upright stems; dies back in winter.

Growth

Moderate; forms a substantial clump over two to three growing seasons.

Care needed

Medium

• Pollinators
• Cold hardy
• Disease resistant
• Wildlife
• Low allergen
• Fragrant

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

Difficulty

Moderate

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

   1.8 ft (0.55 m)

3. After 2 years

   2.6 ft (0.8 m)

4. After 3 years

   3 ft (1.1 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

Growth rate

Moderate

• Water deeply during dry spells, directing water onto the soil rather than the leaves.
• Apply compost and a modest amount of balanced fertiliser in spring; avoid excessive nitrogen.
• Mulch each spring to conserve moisture, keeping mulch clear of the crown.
• Space plants for airflow and keep neighbouring plants from crowding the stems.
• Support stems early with discreet stakes or a grow-through support in exposed sites.
• Divide congested clumps every three to four years in spring.

Pruning. Remove spent flower heads just above a healthy pair of leaves to encourage smaller repeat blooms and limit seedlings. Cut dead stems to ground level in late autumn or late winter; remove diseased foliage promptly.

Early spring

Plant or divide clumps as growth begins, watering thoroughly afterwards.

Spring

Apply compost, fertiliser and mulch; set supports before stems become tall.

Late spring

Check that surrounding growth leaves enough airflow around the stems.

Summer

Water during dry weather and check lower leaves for mildew and spider mites.

Late summer

Deadhead faded flower clusters to extend the display and prevent unwanted seedlings.

Late autumn

Cut down dead stems if tidying now, and remove any diseased plant material.

• Plant in repeated groups through the middle or back of a mixed border for upright white accents.
• Combine with purple coneflowers, salvias and ornamental grasses for a long summer display.
• Use in a white garden with white roses and silver-leaved plants.
• Place near a path or seating area where its fragrance and pale evening flowers can be enjoyed.

Garden styles it suits: Cottage garden, English country, White garden, Pollinator garden, Romantic rose garden and Moon garden.

Plant it with: Purple coneflower, Black-eyed Susan, Garden salvia, Switchgrass, Shasta daisy and Roses.

Wildlife: Flowers provide nectar for butterflies, moths and other pollinating insects. Deer and rabbits may browse the shoots.

• Powdery mildew: 'David' is resistant, not immune; maintain soil moisture, improve airflow and remove badly affected foliage.
• Spider mites in hot, dry weather: look for pale stippling and fine webbing; rinse leaf undersides with water and prevent drought stress.
• Root or crown rot: avoid waterlogged ground and improve drainage before planting.
• Flopping stems: provide early support, increase sunlight and avoid excessive nitrogen feeding.

Not known to be toxic to cats, dogs, horses or people; no part is recognised as poisonous. It is grown as an ornamental, not as a food plant.

• Dame's rocket (Hesperis matronalis)

  Dame's rocket has four petals per flower and alternate leaves; phlox has five petals and opposite leaves. Dame's rocket usually flowers earlier.

• Meadow phlox (Phlox maculata)

  Meadow phlox usually has narrower, more cylindrical flower clusters and purple-spotted stems; 'David' has broader flower heads and generally unspotted stems.

Phlox comes from the Greek word for flame, referring to the bright flowers of some species, while paniculata refers to its branched flower clusters.

Propagation. Divide established clumps in spring, or take basal cuttings in spring. Seedlings may differ from 'David'; use vegetative propagation to retain the cultivar.

Accepted botanical name

Phlox paniculata

In the US and Canada

Native in the lower 48 states. Introduced in Canada.

Native range

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

Measured

Average height 120 cm.

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