Photo credit: Robert H. Mohlenbrock @ USDA-NRCS PLANTS Database / USDA SCS. 1989. Midwest wetland flora: Field office illustrated guide to plant species. Midwest National Technical Center, Lincoln.
FIRST IMPRESSIONS: Phlox paniculata is an upright perennial wildflower with oval or oblong leaves. In summer, the deep green foliage is topped by large flat headed or slightly rounded clusters of fragrant magenta or lavender-pink flowers. Summer phlox forms robust clumps in sunny or lightly shaded sites with moist well drained soils.
HABITAT & HARDINESS: Phlox paniculata occurs from Maine to Georgia and west to Minnesota and Louisiana. This species has a scattered distribution and is not common in the wild.
Phlox paniculata is indigenous to woodland clearings and borders, moist to mesic woods, lightly shaded river banks, meadows, moist roadsides and thickets.
Plants are hardy from USDA Zones 4-8.
PLANT DESCRIPTION: Phlox paniculata is an erect tap-rooted perennial with arching unbranched stems. The stems are smooth and green sometimes with a few purple streaks.
Leaves are oval or oblong with fine hairs along the edges. The blades are up to 6” long and about 1” wide. They are opposite and can have short petioles or sessile rounded bases.
The stems terminate in showy 4-8” wide flower panicles. The fragrant florets are salverform with a long narrow corolla tube that expands into 5 spreading overlapping petal-like lobes. Florets are bright pink, rosy-lavender or occasionally white. They often have dark colored centers or eyes.
Blooming occurs from mid to late summer into early autumn for about 6 weeks. Small inconspicuous oval capsules follow.
Plants grow 2-5’ tall with a 1-3’ spread.
CULTURAL & MAINTENANCE NEEDS: Phlox paniculata flourishes in cool sunny sites with moist rich slightly alkaline soil.
Plants tolerate acid pH but fare better if lime is applied every 2-3 years to sweeten soil.
This species will grow in full sun in cooler areas of the country. In southern climates or hot sites plant should ideally receive 6 hours or so of sun with shade during the hottest part of the day.
This phlox can have issues with powdery mildew. Mildew resistance is enhanced if plants are provided with good air circulation and overhead irrigation is avoided. In hot dry sites plants may be plagued by spider mites.
This species is intolerant of drought and may need irrigation during extended dry periods. Mulching is beneficial to conserve water and keep roots cool.
Deadheading spent flowers can prolong the season of bloom and prevent unwanted seedlings.
LANDSCAPE USES: This species is a good Accent for a Wildlife Garden or Perennial Border. Plants are also used as Butterfly Nectar Plants or as part of a Grouping or Mass Planting. Phlox paniculata has Showy Blooms and is appropriate for Cottage Gardens, Low Maintenance Plantings, Rain Gardens and Perennial Borders.
COMPANION & UNDERSTUDY PLANTS: Try pairing Phlox paniculata with Aster umbellatus, Echinacea purpurea, Eupatorium fistulosum, Coreopsis major, Liatris spicata, Monarda fistulosa, Rudbeckia fulgida var. fulgida or Panicum virgatum.
Phlox maculata has similar appearance and culture and could be substituted in some situations.
TRIVIA: Hundreds of Phlox paniculata cultivars have been selected or hybridized. The selections are generally made for unique flower color, large flower size, dwarf habit or mildew resistance.
Phlox paniculata provides nectar to butterflies, skippers, hummingbird moths, sphinx moths and hummingbirds. Deer, rabbits and livestock browse on the foliage.
Phlox paniculata leaves have unusual branching secondary veins that can be used to identify the species.
For more information on this plant, visit the USDA PLANTS Database: http://plants.usda.gov/java/profile?symbol=PHPA9