How to Grow and Care for Phlox -- Garden Chronicle

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There are many types of phlox. All are known for their showy flower clusters. There are tall-growing phlox that can be used as border plants and there are dwarf-growing varieties that can be used in rock gardens and as edging plants along paths. Most phlox species are perennials; the annual species Phlox drummondii is perhaps the most widely grown.

Annual phlox–botanical name Phlox drummondii— is a bushy annual with neat green leaves and clusters of small pink, red, purple, blue, and white flowers that appear throughout the summer. Leaves are lance-shaped and narrow.

Annual Phlox is a Texas native. Seeds can be sown outdoors after all danger of frost is past. In mild winter and desert regions, seeds can be planted in the fall.

Annual phlox is a good choice for bedding. It can serve as a ground cover for summer-blooming bulbs.

Other phlox species commonly grown in gardens include sand phlox (P. bifida) which grows to 10 inches tall and 2 feet wide; wild blue phlox (P. divaricata) which grows to 12 inches tall and 2 feet wide; thick-leaf phlox (P. maculata) which grows 3 to 4 feet tall and 18 inches wide; summer phlox (P. paniculata) which grows 3 to 5 feet tall and 2 feet wide; creeping phlox (P. stolonifera) which grows 6 to 8 inches tall and 12 inches wide; and moss pink phlox (P. subulata) which grow 6 inches tall and 18 inches wide. See below for more on some of these.

Table of Contents

Get to know annual phlox — Phlox drummondii

Plant type: Annual
Growing Zones and range: Zones 4-9
Hardiness: Tender
Height and width: 6 to 20 inches (15-50cm) tall; up to 10 inches (25cm) or more wide
Foliage: Narrow, inversely lance-shaped to nearly ovate leaves 1-3 inches long
Flowers: Tight clusters of star-shaped flowers 1 inch across
Flower colors: Shades of pink, red, salmon, purple, mauve, and white; many flowers are bicolored
Bloom time: Summer to frost
Uses: Bedding, edging, rock gardens, containers
Common name: Annual phlox, Drummond phlox
Botanical name: Phlox drummondii
Family: Polemoniaceae
Origin: Noth America

Where to plant annual phlox — Phlox drummondii

Plant annual phlox in full sun.
Grow annual phlox in humus-rich, well-drained soil.

Annual phox, Phlox drummondii — Annual phox, *Phlox drummondii*

When to plant annual phlox — Phlox drummondii

Sow annual phlox seeds directly in the garden in early spring in Zones 2-6. In Zones 7-11 sow seeds in late autumn for winter or early spring bloom.

Planting and spacing annual phlox — Phlox drummondii

Space annual phlox 6 to 8 inches apart. Plant annual phlox in groups of a dozen plants or more for best effect.

How to water and feed annual phlox — Phlox drummondii

Annual phlox needs moderate moisture; keep the soil evenly moist.
Fertilize annual phlox with an all-purpose fertilizer every 4 to 6 weeks.

Annual phlox care — Phlox drummondii

Remove spent blooms to encourage new flowers.
Heat will slow or stop annual phlox; the plant will revive in the fall.

Annual phlox varieties to grow

‘Dwarf Beauty’ grow to 6 inches tall.
‘Brilliant’ grows to 2 feet tall.
Globe Mixed are dwarf mounding cultivars.

Annual phlox frequently asked questions

Q: When do I plant annual phlox in the garden?

A: Annual phlox is slightly resistant to frost. You can sow seeds indoors 8 to 10 weeks before the last frost. Set young plants into the garden a few weeks before the last frost as long as the soil is workable. Place phlox where it can grow in full sun.

Q: How do I start phlox from seed?

A: Sow seeds indoors 8 to 10 weeks before the outdoor planting date. Sow seeds in individual pots; seedlings do not like transplanting. Start seeds in a cool room; this is important for germination. Cover the seeds completely; they need darkness to germinate. Be careful not to overwater; young plants are susceptible to damping off.

Q: What care do phlox need in the garden?

A: Fertilize phlox monthly with soluble plant food. Keep phlox well-watered. Remove faded flowers. Cut leggy plants back to encourage compactness. Phlox is fairly heat-resistant but may decline in mid-summer heat.

How to grow woodland phlox – Phlox divaricata

Woodland phlox bear small star-shaped lavender-blue blooms from mid-to-late spring. Woodland phlox is a creeping semi-evergreen perennial bears narrow, lance-shaped mid-green leaves on purplish upright stems.

Get to know woodland phlox

Plant type: Perennial
Growing Zones and range: 3-9
Hardiness: Tender
Height and width: 12”- 18” tall; 1’- 2’ wide
Flowers: Pale blue, pink, white
Bloom time: Mid to late spring
Uses: Shade garden, woodland garden
Botanical name: Phlox divaricata
Common name: Woodland phlox, wild blue phlox

Where to plant woodland phlox

Grow woodland phlox in light or dappled shade.
Plant woodland phlox in humus-rich, well-drained soil that is moisture retentive.

When to plant woodland phlox

Set woodland phlox in the garden inspiring.

Planting and spacing woodland phlox

Space woodland phlox 12 to 18 inches apart.
Work aged compost into the soil before planting.

How to water and feed woodland phlox

Woodland phlox grow best in evenly moist soil; do not let the soil dry out.
Feed woodland phlox by adding aged compost to the soil and by mulching with aged compost.

Woodland phlox care

Mulch around woodland phlox with aged compost.
Cut woodland phlox back after flowering to promote more blooms and compact growth.
Divide plants after blooming or in the fall.
Woodland phlox may be attacked by slugs,
Woodland phlox is susceptible to mildew.

Woodland phlox varieties to grow

‘Dirogo Ice’ bears clear, pale blue flowers.
‘Fuller’s White’ is compact and white-flowered.

Phlox maculata — Wild sweet William, spotted phlox

Phlox maculata resembles garden phlox, this native species blooms a month earlier and the flower clusters form more conical clusters. The darker green leaves resist mildew. The lightly fragrant, 1 ½ -inch flowers pack themselves tightly together into showy clusters that top the tall stems in early summer and again later in the year if cut back. Light magenta-pink in the species, garden varieties boast more attractive colors, including snow-white and purer pinks. The upright, hairy stems are usually mottled red.

Size: 2 to 3 feet tall; 2 feet wide.

Light: Full sun to light shade.

Soil and moisture: Fertile, humus-rich, moist, well-drained soil; plentiful moisture.

Planting and propagation: Plant bare-root or container-grown plants in spring, spacing 2 ½ feet apart. Divide every three or four years in spring.

Special care: Cut back after blossoms fade to encourage rebloom.

Pests and diseases: More resistant to mildew than garden phlox but affected some. Provide good air circulation; avoid overhead watering.

Climate: Zones 3-9.

Cultivars: ‘Miss Lingard,’ snow-white, sometimes listed as P. Carolina; ‘Omega,’ white with lilac eye; ‘Alpha,’ rose-pink with dark eye; ‘Rosaline,’ dark pink.

Garden use: Spectacular massed in borders.

How to grow summer garden phlox — Phlox paniculata

Garden phlox–botanical name Phlox paniculata— bears fragrant, five-petaled flowers in clusters from early summer to mid-autumn. The fragrant flowers are white or pale to dark lilac. Garden phlox is an herbaceous perennial with lance-shaped toothed, thin leaves, a good choice for mass plantings and borders.

Get to know summer garden phlox

Plant type: Perennial
Growing Zones and range: 4-8
Hardiness: Hardy to -35° (-37°C)
Height and width: 24 inches to 4 feet (1.2m) tall; 24 to 39 inches (60-100cm) wide
Foliage: Ovate or lance-shaped to elliptic, toothed, thin leaves 2 to 5 inches (1.5-2.5cm) long
Flowers: Salverform (a narrow tube with petals bent abruptly outward at right angles) blossoms on panicle-like cymes
Flower colors: Wild forms are magenta; hybrids are shades of pink, red, lilac, or white and some are bicolored
Bloom time: Early, mid-, or late summer depending on the variety
Uses: Mass plantings, borders
Common name: Garden phlox, summer phlox
Botanical name: Phlox paniculata
Family: Polemoniaceae
Origin: North America

Where to plant summer garden phlox

Plant garden phlox in full sun in Zones 3-6; plant in light shade in hot-summer regions in Zones 7-9.
Grow phlox in compost-rich, well-drained soil.

When to plant summer garden phlox

Set garden phlox in the garden in spring or fall.

Planting and spacing summer garden phlox

Space garden phlox 18 to 24 inches apart. Space plants so that they are not crowded; crowded plants are susceptible to mildew.

How to water and feed summer garden phlox

Garden phlox wants ample moisture; do not let the soil dry out.
Fertilize garden phlox with an all-purpose, slow-release fertilizer each spring.

Summer garden phlox care

Mulch around garden phlox to conserve soil moisture.
Cut garden phlox back by one-third after blooming to encourage new blooms.
Cut back garden phlox that is attacked by mildew.

Summer garden phlox propagation

Phlox paniculata seeds will germinate in 5-10 days at 60-65°F (16-18°C).

Summer garden phlox varieties to grow

There are numerous cultivars of Phlox paniculata.
Mildew-resistant cultivars include ‘Miss Lingard’, ‘Mt. Fuji’, ‘David’, ‘Franz Schubert, and ‘Eva Cullum’.
Phlox maculata, also called wild sweet William or spotted phlox is more mildew resistant than Phlox paniculata.

White and purple creeping phlox cascading over an old stone wall in the spring

How to grow creeping phlox – Phlox stolonifera

Creeping phlox–botanical name Phlox stolonifera– is a low-spreading perennial that bears a profusion of pale to deep purple starry flowers. Creeping phlox is a perennial with obovate, dark green leaves two inches long.

Creeping phlox generally remains under 12 inches tall. Creeping phlox has slightly larger flowers than other phlox.

Get to know creeping phlox

Plant type: Perennial
Growing Zones and range: 2-8
Hardiness: Hardy to -35°F (-37°C)
Height and width: 6 to 12 inches tall; 8 to 12 inches wide
Foliage: Obovate, dark green leaves to 2 inches (5cm) long
Flowers: Salverform flowers on upright stems; flowers appear in small clusters
Flower colors: Pale to deep purple, pink
Bloom time: Summer
Uses: Groundcover, shade gardens, woodland gardens
Common name: Creeping Phlox
Botanical name: Phlox stolonifera
Family: Polemoniaceae
Origin: Woodlands in Central America

Where to plant creeping phlox

Plant creeping phlox in light shade in Zones 2-6; plant in full or dappled shade in Zones 7-8. Plants in cool summer regions can tolerate the sun.
Creeping phlox need humus-rich, well-drained soil that is moisture retentive.

Creeping phlox uses and companions

Use Phlox stolonifera as a ground cover.
Grow Phlox stolonifera in a shade or woodland garden.

When to plant creeping phlox

Set creeping phlox in the garden in spring.
Add aged compost to the soil at planting time.

Planting and spacing creeping phlox

Space creeping phlox 8 to 12 inches apart.

How to water and feed creeping phlox

Creeping phlox need to be kept well-watered. Do not let the soil dry out.
Fertilize creeping phlox with aged compost.

Creeping phlox care

Mulch around creeping phlox to conserve soil moisture. Be careful that mulch does not cover leaves.
Creeping phlox will reseed if you let the flowers go to seed.
Creeping phlox also spreads by underground runners.
Mildew and slug can attack creeping phlox.

Creeping phlox propagation

Phlox stolonifera seeds will germinate in 5 to 10 days at 608° to 65°F (16°-18°C).

Creeping phlox varieties to grow

There are several Phlox subulata cultivars:

‘Ariane’ and ‘Bruce’s White’ has white flowers.
‘Blue Ridge’ has sky blue flowers and grows to 12 inches tall.
‘Home Fires’ and ‘Pink Ridge’ has deep pink flowers.
‘Sherwood Purple’ bears purple-blue fragrant flowers.

Creeping phlox, Phlox subulata — Creeping phlox, *Phlox subulata*

How to grow moss phlox – Phlox subulata

Moss phlox or creeping phlox–botanical name Phlox subulata–is a dense evergreen perennial that forms cushions of bright green leaves. Starry purple or red, sometimes violet-purple, lilac, pink, or white flowers appear in groups in late spring and early summer.

Moss Phlox–Phlox subulata–can be used as a small-scale ground cover or foreground plant in beds and borders. Moss phlox flowers for a month starting in late spring. The plant is smothered in small blossoms, lavender-blue, white, and shades of pink and violet.

Get to know moss phlox

Plant type: Evergreen perennial
Growing Zones and range: 2-9
Hardiness: Hardy to -30ºF (-34ºC); moss phlox does not like heat or drought.
Height and width: 2 to 6 inches (5-15cm) tall; to 20 inches (50cm) wide
Habit: Lax, forming cushions or mats
Foliage: Hairy, linear to elliptic, bright green leaves to 3/4 inch long
Flowers: Star-shaped petal lobes; white, pink, or lavender blooms
Bloom time: Spring blooms followed by lush green foliage
Uses: Matlike groundcover, hillsides
Common name: Moss Phlox, creeping phlox
Botanical name: Phlox subulata
Family: Polemoniaceae
Origin: North America

Where to plant moss phlox

Plant moss phlox in full sun.
Grow moss phlox in average or poor, rocky soil that is dry. Moss phlox prefers alkaline soil.

Moss phlox uses and companions

Use Phlox subulata as a ground cover or bedding in informal beds and borders.
Plant Phlox subulata in a rock garden.
Good companions for moss phlox include Aster, Chrysanthemum, Monarda, Physostegia viginiana, Platycodon grandiflorus.

When to plant moss phlox

Set established moss phlox in the garden in spring. Divide plants in the fall.

Planting and spacing moss phlox

Space moss phlox 18 to 24 inches apart.

How to water and feed moss phlox

Moss phlox grows in soil that is just moist, not wet; water moss phlox occasionally after it is established. Moss phlox does not like heat or drought.
Moss phlox does not require fertilizing.

Moss phlox care

Cut moss phlox back to encourage dense growth and continued flowering.
Moss phlox is susceptible to spider mites in hot, dry conditions. It is susceptible to root rot in wet winter conditions.