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Phlox paniculata spp. (Tall Phlox Mix)
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© Vasu Raghavan, some rights reserved (CC-BY-SA) · GBIF

Phlox paniculata

Tall Phlox Mix

At a Glance

HabitUpright
FoliageDeciduous
Height24-48 inches (60-120 cm)
Width18-30 inches (45-75 cm)
Maturity3 years

Growing Zones

USDA Hardiness Zones

3 - 9
These zones indicate the coldest temperatures this plant can typically survive.
What's my zone? →
Frost Tolerancehardy

Overview

Phlox paniculata is a clump-forming herbaceous perennial reaching 24-48 inches (60-120 cm) tall and 18-30 inches (45-75 cm) wide at maturity, typically within 2-3 growing seasons. Stiff upright stems carry opposite, lance-shaped, mid-green leaves 3-5 inches (7.5-12 cm) long with smooth or slightly hairy surfaces. Each stem terminates in a domed panicle 4-8 inches (10-20 cm) across composed of 30-60 trumpet-shaped flowers; individual flowers are 0.75-1.25 inches (2-3 cm) across with five flat petal lobes around a small open throat. Wild populations and unselected mixes carry flowers in pink to purple-pink with a darker eye; cultivar selections extend the color range to white, magenta, scarlet, lavender, and bicolors. Bloom period runs 4-6 weeks in mid- to late summer (July-August in zones 4-7). Light sweet fragrance carries on warm evenings. Powdery mildew is the main disease issue in humid summers, particularly on plants with crowded basal foliage; thinning to 4-6 strongest stems per crown improves air circulation. Plants self-seed where soil is bare; seedlings often revert to the magenta-pink wild type rather than the parent cultivar.

Native Range

Phlox paniculata is native to eastern and central North America, occurring in moist woodlands, streambanks, and meadows from southern New York and Ontario south to Georgia and west through the Ohio and Mississippi River valleys. The species ranges naturally at elevations from sea level to 2,500 feet (760 m).

Suggested Uses

Used in full-sun to part-sun perennial borders, cottage gardens, and pollinator beds at 18-30 inch (45-75 cm) spacing. Planted alongside Echinacea, Rudbeckia, and Monarda in summer-flowering mixed plantings. Grows in containers of at least 5 gallons (19 L) with consistent moisture; container plants are more susceptible to powdery mildew than in-ground plants.

How to Identify

Stiff upright herbaceous perennial 24-48 inches (60-120 cm) tall with opposite, lance-shaped mid-green leaves 3-5 inches (7.5-12 cm) long. Terminal domed panicles 4-8 inches (10-20 cm) across hold 30-60 trumpet-shaped flowers each 0.75-1.25 inches (2-3 cm) wide with five flat petal lobes. Distinguished from Phlox maculata (meadow phlox) by smaller flower clusters and unbroken stems; P. maculata stems show purple flecking.

Appearance

Size & Dimensions

Height2' - 4'
Width/Spread1'6" - 2'6"

Reaches mature size in approximately 3 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~6 weeks
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Mid-July through late August in zones 4-7, typically 4-6 weeks of continuous flowering per established clump. In zones 8-9, flowering begins in late June and may end before mid-August due to summer heat. In zones 3 and the colder parts of zone 4, flowering shifts to early August through mid-September. Removing the central inflorescence at first bloom causes lateral panicles to develop, extending the display by 2-3 weeks.

Detailed Descriptions

Flower Description

Pink to purple-pink dominant in unselected mixes; cultivars extend to white, magenta, scarlet, lavender, and bicolors

Foliage Description

Mid-green, lance-shaped

Growing Conditions

Sun Requirements

Requires 5-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)
357912
Soil Types
Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

2-3 years

Care & Maintenance

Care Guide

Establish in moist, fertile, well-drained loam at pH 6.0-7.5 in full sun to part sun. Water weekly during the growing season; consistent moisture reduces powdery mildew incidence and supports flower size. Apply 2-3 inches (5-7.5 cm) of compost annually in early spring as a feed and mulch. Powdery mildew (Erysiphe cichoracearum) appears as white coating on lower leaves in mid-summer; cultivars vary in resistance, and thinning to 4-6 strongest stems per crown reduces severity. Rabbits and deer feed on emerging shoots in spring; physical barriers protect new growth. Divide every 4-5 years in early spring or autumn to maintain vigor and bloom production.

Pruning

Cut stems to ground level in late autumn after first hard frost; powdery-mildew-affected foliage is typically removed from the site rather than composted. Pinching growing tips of the strongest 4-6 stems per crown by 25% in late spring delays bloom by 2-3 weeks and reduces ultimate height. Cut spent flower stalks individually after bloom to prevent self-seeding.

Pruning Schedule

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fall

Maintenance Level

moderate

Container Growing

✓ Suitable for container growing

Minimum container size: 5 gallons

⚠️ Toxicity Warning

Non-toxic