After the initial spring flush of flowers dies down and you need some bright color to decorate your landscape, an easy, summer-blooming flower like "Victoria" summer phlox (Phlox paniculata "Victoria") can provide just the right touch. Named a "Texas Superstar" by Texas A&M University, this perennial flower can overwinter in much of the United States, attracting butterflies and hummingbirds while in bloom.
"Victoria" summer phlox grows 3 feet tall and 2 feet wide, although, depending on the fertility of the soil, it may grow larger. The dense foliage is light green. In mid-summer, rounded clusters of 1-inch magenta, lavender or violet flowers bloom above the plant's foliage. "Victoria" summer phlox has a more open growth habit than the similar "John Fanick" summer phlox (Phlox paniculata "John Fanick"), perennial in U.S. Department of Agriculture plant hardiness zones 4 through 8.
Climate and Culture
Gardeners can grow this summer phlox as an annual, but it can overwinter in USDA zones 4 through 10. It prefers full sun, but it can grow in light shade as well. It thrives in moist, rich, well-draining soils but can also perform in less fertile conditions with some organic matter added to the soil before planting. The soil should have a pH between 5.6 and 7.5 for optimum growth.
Once established, "Victoria" summer phlox are heat and drought tolerant. They require a moderate amount of water, but don't keep the soil constantly wet as this will kill the plant. Placing a layer of mulch around the base of the plants will keep the roots cool in the summer and help conserve moisture. Applying balanced fertilizer in spring as new shoots appear will encourage strong, healthy growth. Shear the plant after the first bloom dies down to encourage another bloom cycle, and cut down to the ground after the first frost. To propagate the plant, divide the clumps in the spring. The seeds may grow more phlox plant but they will not be true to the parent plant.
This plant has few problems. Over-watering can encourage root rot, which you cannot cure in a plant. To avoid this, allow the top 2 to 3 inches of soil to dry between watering sessions. Although this particular phlox is relatively resistant to the powdery mildew to which other varieties may be susceptible, it can still contract the disease. Use a soaker hose to water, or water early in the morning to give the foliage of the plant some time to dry. Thin out the dense stems and plant in an area with good air circulation to further reduce the risk of this disease.