Garden Phlox Plants: Tips For Growing And Care Of Garden Phlox

Pink Garden Phlox Plant
garden phlox 1
(Image credit: Mindstyle)

Nothing beats the appeal of garden phlox plants. These tall, eye-catching perennials are ideal for sunny borders. In addition, the large clusters of pink, purple, lavender or white flowers bloom for several weeks in summer, and make excellent cut flowers. Growing hardy garden phlox is simple and so is its general care.

Info on Garden Phlox

Garden phlox (Phlox paniculata), also called summer phlox, is a sun-loving perennial with a long flowering season. Large clusters of flowers, called panicles, sit atop stems that grow 3 to 4 feet (91 cm. to 1 m.) tall. This native American wildflower thrives in USDA plant hardiness zones 4 to 8. Growing hardy garden phlox is a challenge in hot, humid areas because the plant is sensitive to powdery mildew. Watch for foliage that looks as though it has been dusted with talcum powder, and pinch off the affected leaves. In severe cases, treat the plants with fungicide. You may be able to avoid powdery mildew by choosing varieties labeled as “mildew resistant.”

Care of Garden Phlox

Set out new garden phlox plants in early spring. Choose a sunny location with moist but well-draining soil. Work some compost into the soil before planting if your soil doesn't manage water well. Give the plants plenty of room, especially in hot, humid areas where air circulation around the plant will help keep powdery mildew to a minimum. Use the recommended spacing on the plant tag, which is usually 18 to 24 inches (46 to 61 cm.). Fertilize with a shovelful of compost for each plant or a light application of 10-10-10 fertilizer at planting time and again just before the flowers open. If you fertilize once more after the flowers fade, you may get another flush of flowers. Water garden phlox plants weekly for the first few weeks and often enough to keep the soil lightly moist thereafter. Keep the foliage as dry as possible by applying the water to the soil rather than the foliage. Spread a 2- to 3-inch (5 to 7.5 cm.) layer of mulch around the plants to help the soil hold moisture. Care of garden phlox also includes the clipping of flower stems after the flowers fade. This keeps the plants looking tidy, and also prevents the flowers from dropping seeds. Since garden phlox plants are generally hybrids, the seedlings that result from dropped seeds won't resemble the parent plants.

How to Grow Tall Garden Phlox

Many people wonder how to grow tall garden phlox. To get the maximum height from tall garden phlox, clip the weakest stems from the plant when they are about 6 inches (15 cm.) tall, leaving only five or six stems on the plant. Pinch out the tips of the remaining stems to encourage a tall, bushy growth habit.

Jackie Carroll

Jackie Carroll has written over 500 articles for Gardening Know How on a wide range of topics.