There are literally thousands of species and varieties available. Among those that deserve consideration are several species of Phlox . Garden phlox is a clump-forming, upright plant which produces large, showy flower clusters in summer. 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.