Phlox Description and Cultural Information
There are basically three groups of Phlox: the low growing, mounding species; the woodland species; the tall garden species.
1) Low growing, mounding species: Phlox bifida, P. douglasii, P. x 'Chattahoochee', and P. subulata. Phlox subulata is the most widely grown plant in commerce.
Phlox subulata, creeping phlox, moss phlox. 4 - 8". This low growing phlox is by far the best known of the low growing species. It has short, needle-like foliage that is completely hidden by pink, blue, or white flowers for several weeks in spring. 'Candy Stripe' has white flowers striped in pink. 'Coral Eye' is pale pink with a coral eye. 'Scarlet Flame' is a bright scarlet-pink. 'Snowflake' is pure white. Zones 2 - 8.
How to Grow: Plant creeping phlox in average, sandy, well-drained soil in full sun. In soil that is too shady they will be sparse and leggy, and in too much moisture they may rot. To propagate you can divide plants in fall or take stem cuttings in summer. In the right spot it is very easy to grow.
Landscape uses: Creeping phlox is a great plant for the edge of the border or in rock gardens. Since it only blooms in the spring followed by months of foliage, consider a spot where it can be enjoyed in the spring but be far enough away to get lost during the summer.
2) Woodland species: Phlox divaricata and Phlox stolonifera.
Phlox divaricata, woodland phlox. 10 - 15". Woodland phlox develops an upright, spreading clump of thin, dark green leaves with fragrant lavender-blue flowers in early spring. 'Fuller's White' has pure white flowers. 'Louisiana Blue' is a pale purple. 'Montrose Tricolor' is an attractive variegated plant with fragrant lavender blue flowers. Zones 4 - 8.
Phlox stolonifera, creeping phlox. 6 - 8". This woodland phlox forms dense clumps from creeping stems. It has small oval foliage and upright bloom clusters of lavender to pink flowers in spring. Zones 5 - 8.
How to Grow: The woodland species of phlox are native to woodland edges. Plant them in evenly moist, humus-rich soil in partial shade. Move plants after flowering if they start to crowd out their neighbors.
Landscape uses: Use woodland phlox in the transition areas of the partial shade garden. Combine them with spring bulbs, spring wildflowers, bleeding hearts, foamflowers (Tiarella), Pulmonaria, ferns, hostas, and columbine (Aquilegia).
3) Tall garden species: Phlox carolina, Phlox maculata, Phlox ovata, and Phlox paniculata.
Phlox carolina, Carolina phlox. 3 - 4'. This phlox has oval leaves on stout stems with pink, purple or white flowers in late spring. Zones 4 - 9.
Phlox maculata, wild sweet William. 2 - 3'. This phlox is similar to Carolina phlox but has narrow foliage white, pink, or purple flowers in late spring and early summer. 'Natascha' is an attractive bi-color phlox with magenta-pink and white petals. Zones 3 - 9.
Phlox ovata, mountain phlox. 1 - 2'. This spreading phlox has oval leaves and white, pink, or magenta flowers in late spring. Zones 4 - 8.
Phlox paniculata, garden phlox. 3 - 4'. This is by far the most popular tall garden phlox and the last to bloom in mid to late summer. They have large, domed flower clusters on tall stems covered with lance-shaped leaves. There is a very wide range of colors among hundreds of hybrids. Many of the hybrids are also mildew resistant. Blue to purple shades include 'Blue Boy', 'Blue Paradise', 'Franz Schubert', 'Laura', and 'The King'. 'Orange Perfection' is a bright orange. 'Sandra' has scarlet blooms. Pink shades include the mildew resistant 'Bright Eyes', 'Eva Cullum', 'Fairest One', and the very mildew resistant 'Robert Poore'. 'Red Riding Hood' is a shorter red. 'Starfire' is a bright red. 'David' is a very mildew resistant white. 'Creme de Menthe' has light pink flowers with a darker pink eyezone and variegated foliage. Zones 4 - 8.
How to Grow: Plant tall garden phlox in average to rich, moist but well-drained soil in full sun to partial shade. Give them excellent soil, regular watering, occasional fertilizer, and good air circulation to help prevent powdery mildew. Plants in good soil with regular watering do not mildew compared with plants that are underwatered or stressed out, plus if you plant the crowns about 2 to 3" below the soil and mulch lightly it will help them grow better by keeping them cool and moist. Propagate by stem cuttings or division in spring, or by root cuttings in fall.
Landscape uses: Garden phlox are great for the middle and back of the perennial garden. They will tolerate partial shade and can be used on the east or west side of homes or buildings where they will be shaded out for part of the day. Combine them with other summer blooming perennials such as obedient plant (Physostegia), Helianthus, asters, Geranium, daylilies, purple coneflower (Echinacea), Rudbeckia, penstemons, Shasta daisies, Monarda, and ornamental grasses.