Common Name: smooth phlox
Type: Herbaceous perennial
Zone: 3 to 8
Height: 1.50 to 2.00 feet
Spread: 1.00 to 1.50 feet
Bloom Time: April to May
Bloom Description: Rose to reddish-purple
Sun: Full sun to part shade
Suggested Use: Naturalize
Flower: Showy, Fragrant
Attracts: Hummingbirds, Butterflies
Easily grown in moderately fertile, medium moisture, well-drained soil in full sun to light shade. Prefers moist, organically rich soils in full sun. Plants are intolerant of drought and need to be watered in dry spells. Tolerates more soil moisture than most other species of phlox. Also tolerates hot and humid summer weather. Remove faded flower panicles to prolong bloom period. If not deadheaded, plants will self-seed in optimum growing conditions. Can slowly spread over time by both slender rhizomes and self-seeding to form large colonies.
Phlox glaberrima, commonly called smooth phlox, is native from Virginia to Wisconsin south to Florida and Texas. It typically occurs in moist meadows, low woods and along riverbanks. It is an upright, clump-forming, rhizomatous perennial which typically grows 1-3’ tall. Sweetly-aromatic, tubular, 5-lobed, rose to reddish purple flowers (to 1” across) with long corolla tubes are densely arranged in large, pyramidal, terminal clusters (panicles to 12” long) atop stiff, upright stems that seldom need staking. This is one of the few tall phloxes to bloom in spring (late April to May in St. Louis). Very thin, opposite, finely-toothed, lance-shaped, dark green leaves (to 4” long). As the common name suggests, this plant is essentially hairless. ‘Morris Berd’ is a compact cultivar that typically grows to 18-22” tall and features large panicles of rose-pink flowers and dark green leaves (to 3” long).
Although many species of phlox are susceptible to powdery mildew and root rot, this species of phlox is noted for having excellent resistance to both problems. It grows quite well in the St. Louis climate and is relatively maintenance free. Watch for spider mites, particularly in hot, dry conditions.
Smooth phlox is an excellent spring-blooming phlox for the perennial border, cottage garden, wildflower meadow or native plant garden.