Mostly from North America, the many types show wide variation in form, but all have showy flower clusters. Tall kinds are excellent border plants; dwarf ones are mainstays of the rock garden. Unless otherwise noted, grow in ordinary garden soil and provide regular moisture. Two common problems affect phlox: red spider mites (attack almost all species) and powdery mildew (P. pani- culata is especially susceptible). Horticultural oil or insecticidal soap controls the first; planting resistant selections solves the second.
P. x arendsii. Zones US, MS, LS, CS; USDA 6-9. Hybrid between P. divaricata and P. paniculata. To 1 ft. high, not quite as wide, with 1-in.-wide blossoms in clusters to 6 in. across, early summer. Cut off faded owers for later rebloom. Selections include reddish pur- ple 'Anja'; lavender 'Hilda'; and 'Suzanne', bearing white blooms with a red eye. Mildew-resistant 'Eyecatcher' bears light pink flowers with darker reddish centers. 'Miss Jill' (white with a small pink eye) and 'Miss Mary' (dark red) are part of the mildew-resistant Spring Pearl series. 'Ping Pong' is a mildew-resistant selection with soft rose flowers, reddish green leaves, and reddish stems.
P. bifida. SAND PHLOX. Zones US, MS, LS; USDA 6-8. From the central U.S. Clumps to 810 in. tall, 68 in. wide, with narrow, light green leaves. Blooms spring through early summer, bearing profuse, -in., lavender to white flowers with deeply notched petals. 'Betty Blake' has dark, lavender-blue blooms. Likes full sun and excellent drainage; tolerates drought.
P. buckleyi. Zones US, MS, LS; USDA 6-8. Native to Virginia and West Virginia. Trailing stems, set with willowlike evergreen leaves to 5 in. long, form a clump to 6 in. tall, 2 ft. wide. Upright stems to 1 ft. high hold clusters of rosy purple flowers in late spring and summer. Makes a good ground cover.
P. carolina 'Miss Lingard'. US, MS, LS, CS; USDA 6-9. Popular selection of a species native to the central and eastern U.S. Grows about 3 ft. high and half as wide, with pure white, highly fragrant blooms in early summer. Heat tolerant and mildew resistant. Excellent cut flowers.
P. divaricata. BLUE PHLOX. Zones US, MS, LS, CS; USDA 6-9. Native to eastern North America. To 1 ft. high, 2 ft. wide, with creeping underground shoots. Slender stems are clothed in oblong, 1- to 2-in.-long leaves. Blooms in spring, bearing open clusters of - to 1-in.-wide, somewhat fragrant blossoms; color varies from pale blue (sometimes with pinkish tones) to white. Flowers of 'Dirigo Ice' are palest blue. 'Blue Moon' has deep violet-blue blooms; flowers of 'Louisiana Purple' are an intense blue-purple. 'Montrose Tricolor' has lavender-blue blossoms and leaves variegated in pink, white, and green. P. d. laphamii 'Chattahoochee' has pale lavender-blue blooms with a purple eye. All are good in rock gardens or as bulb covers. Grow in good, deep soil. Light shade.
P. drummondii. ANNUAL PHLOX, DRUMMOND PHLOX. Zones US, MS, LS, CS, TS; USDA 6-11. Native to Texas. To 618 in. high, 1012 in. wide, with erect, leafy stems more or less covered with rather sticky hairs. Lance-shaped to oval, nearly stalkless leaves are 13 in. long. Profuse blossoms in tight clusters at tops of stems. Comes in bright and pastel colors (no blue or orange), some with contrasting eye. Tall strains (about 1 ft. high) in mixed colors include Finest and Fordhook Finest. Hybrid Intensia series stands up to heat and humidity and blooms in shades of pink, magenta, lavender, and white on 12-in. plants. Dwarf (6- to 8-in.) strains include Beauty and Globe, both with roundish flowers; and starry-blossomed Petticoat and Twinkle Star. Bloom period lasts from early summer until frost if faded flowers are removed. Plant in fall. Grow in light, rich soil well amended with organic matter. Full sun.
P. glaberrima triora. SMOOTH PHLOX. Zones US, MS, LS, CS; USDA 6-9. From the eastern U.S. Grows to 12 ft. tall, 11ft. wide, with smooth, narrow, 3-in.-long leaves. Lavender-pink owers in late spring. This species is mildew free. 'Triple Play' has pink flowers with a dark eye and leaves variegated white.
P. latifolia (P. ovata). MOUNTAIN PHLOX. Zones US, MS, LS; USDA 6-8. From the eastern U.S. To 1520 in. tall, 1 ft. wide, with smooth, green, oval, mildew-free leaves to 6 in. long. Deep pink owers in late spring.
P. maculata. MEADOW PHLOX, THICK-LEAF PHLOX. Zones US, MS, LS; USDA 6-8. Native to eastern North America. To 34 ft. tall, 1 ft. wide, with thick, narrow, pointed leaves 24 in. long. Early summer flowers about -in. wide in 15-in.-long clusters; colors range from white (often with a colored eye) through pink shades to magenta. Shiny, mildew-resistant foliage. Selections include 'Alpha', rose-pink; 'Delta', white with pink eye; 'Natascha', pink and white bicolor; 'Omega', white with purplish pink eye; and 'Rosalinde', deep rose-pink. 'Flower Power' has tall, airy, dark stalks of white flowers blushed pink with a small pink eye.
P. 'Minnie Pearl'. Zones US, MS, LS, CS. USDA 6-9. A naturally occurring hybrid found in Mississippi. To 12 in. high and twice as wide. Early-blooming, large, bright white flowers. Mildew resistant.
P. nivalis. TRAILING PHLOX. Zones US, MS, LS; USDA 6-8. Native to central U.S. Trailing plant to 46 in. high, 1 ft. wide. Forms a loose mat of narrow, inch-long leaves. Pink or white, 1-in. flowers in fairly large clusters, late spring or early summer. Excellent in rock gardens; needs good drainage. 'Camla' is a good pale salmon-pink selection. 'Snowdrift' has pure white blooms.
P. paniculata. SUMMER PHLOX. Zones US, MS, LS, CS; USDA 6-9. From eastern North America. To 35 ft. tall, 2 ft. wide, with narrow, 2- to 5-in.-long leaves tapering to a slender point. Fragrant, 1-in. flowers in large, dome-shaped clusters throughout summer. Colors include white and shades of lavender, pink, rose, and red; blooms of some selections have a contrasting eye. Plants do not come true from seedmost seedlings tend toward an uncertain purplish pink, though some may be attractive.
Summer phlox thrives in full sun. After setting out young plants, pinch stem tips to induce branching. Mulch to keep roots cool. Divide every few years, replanting young shoots from outside of clump.
Very susceptible to mildew at end of bloom season. To minimize the problem, provide good air circulation: Don't crowd plants, and thin mature plants to leave only six to eight stems. Plant mildew-resistant selections 'Blue Paradise', deep violet-blue; white-flowered 'David' and 'Mt. Fuji' ('Fujiyama'); 'Delta Snow', white with purple eye; 'Eva Cullum', pink with red eye; 'Franz Schubert', lilac-pink; 'John Fanick', light pink with darker throat; 'Laura', purple with white eye; 'Nicky', deep magenta; compact (1215 in. high) 'Pina Colada', white; 'Robert Poore', violet-pink; and 'Shortwood', bright pink with darker center. The free-blooming, disease-resistant Volcano series comes in a full range of flower colors, some with darker or contrasting centers. 'Becky Towe' has leaves edged with light gold and dark-centered, red flowers. 'Lord Clayton' has dark purple new leaves with green veins that age to bronzy purple-green; pinkish red flowers.
P. pilosa 'Forest Frost'. US, MS, LS; USDA 6-8. A Mississippi selection of prarie phlox, an Eastern North American native. To 18 in. high and 2 ft. wide. Star-shaped, pure white, fragrant flowers. Small, needlelike green leaves. Beautiful planted in drifts.
P. stolonifera. CREEPING PHLOX. Zones US, MS, LS; USDA 6-8. Old favorite from eastern North America. Creeping, mounding plant to 68 in. high, 1 ft. wide, with narrow evergreen leaves to 1 in. long. Profuse springtime show of 1-in. lavender flowers. Selections include lavender-blue 'Blue Ridge', white 'Bruce's White', deep lavender 'Sherwood Purple' and lavender-pink 'Weesie Smith'. Light shade.
P. subulata. MOSS PINK. Zones US, MS, LS; USDA 6-8. From eastern U.S. Forms a mat to 6 in. high, 1 ft. or wider, with creeping stems clothed in -in., needlelike evergreen to semievergreen leaves. Blooms in late spring or early summer, bearing -in. flowers in colors including white, pale to deep shades of pink, and lavender-blue. Makes sheets of brilliant color in rock gardens. Plant in loose, not-too-rich soil; give moderate water. After flowering, cut back halfway. Specialists offer two dozen or more selections of this old Southern favorite; many are actually selections of other low-growing species, or hybrids between those species and P. subulata. 'Tamaongalei' ('Candy Stripe') has rose-pink blossoms edged in white; it is somewhat drought tolerant and has good fall rebloom.