Plants are generally 2 to 4 feet tall. While the species itself is seldom grown in gardens, there are numerous varieties available. Gardeners can choose from white, pink, red, blue, and purple flowering varieties. Unfortunately, most varieties of garden phlox are susceptible to powdery mildew. Powdery mildew produces a grayish white coating on the stems and leaves of infected plants.
Infected leaves turn yellow and eventually dry up and turn brown.
Mildew infected plants become ugly eyesores in perennial gardens. As a result, the popularity of garden phlox has declined in recent years. While good cultural practices, such as adequate plant spacing, can reduce the severity of powdery mildew, gardeners wishing to plant garden phlox should select mildew resistant varieties. Garden phlox grows best in moist, fertile, well-drained soils in partial to full sun. Plants often need to be watered during hot, dry periods.