Phlox are an old-time garden favorite. They are a low-maintenance perennial with a lovely, light fragrance. They come in several varieties: garden phlox, spotted phlox, woodland phlox and carpet-like phlox. Flowers are small and star shaped; colors vary according to the cultivar, including white, pink, red and purple. Uses vary according to the variety; they can be used as a ground cover, in a rock garden or at the back of a garden bed. These versatile plants attract butterflies and hummingbirds.
Varieties and Uses
Phlox paniculata--commonly known as garden phlox--is a sun-loving perennial whose flower clusters appear during the summer. Garden phlox reach a height of 2 to 4 feet, and due to their height they are often used in the back of a garden bed. Another variety is spotted phlox (Phlox maculate). Blossoms are conical in shape. Spotted phlox reach a height of 2 to 3 feet. If you are looking for an early bloomer, then woodland phlox would be an excellent choice. Its blue/violet flower clusters appear from April through June. This variety is shorter than garden and spotted phlox reaching a height of 12 to 15 inches. The lowest growing variety of phlox (growing to a height of 4 to 6 inches) is carpet-like phlox, also known as creeping or moss phlox. Creeping phlox are often used as a ground cover or in rock gardens.
Phlox require a site that has moist, organically rich, well-drained soil. Sunlight and shade requirements vary according to the cultivar. Spring is the best time to plant phlox. However, you can plant them anytime throughout the growing season. Space plants 1 to 2 feet apart, depending on the type of phlox. Garden phlox are susceptible to mildew and planting them far enough apart allows the air to circulate between plants, which helps to prevent powdery mildew from developing. The National Gardening Association recommends applying a thin layer of compost each spring, and also a 2-inch layer of mulch to retain moisture and to control weeds.
Phlox will require watering during the summer months if rainfall is less than 1 inch per week. Since garden phlox are susceptible to powdery mildew, be careful to water close to the base of the plant. Early morning watering also helps the plants to dry out and aids in preventing disease. During the growing season, cut back old blossoms to encourage new blossoms to form. Tall garden phlox should be divided every two to three years, which will produce vigorous plants. In the fall after the first hard frost, cut phlox down to approximately 1 to 2 inches above the soil level.
Diseases and Pests
Plants with powdery mildew have a grayish-white powdery residue on their leaves and stems. As the disease progresses the leaves turn yellow and die. Spacing plants far enough apart to provide air circulation will help alleviate the problem, as well as watering early in the morning. The best way to avoid the problem is to purchase disease-resistant cultivars such as David or Eva Cullum.
Spider mites attack the leaves of the plant by sucking liquid out of the foliage. This causes the leaves to turn dry and brown. Infestations are worse when the weather is hot and dry. The best defense against spider mites is to maintain healthy plants by following a regular program of watering and fertilization. If you have a severe infestation, Iowa State University recommends spraying with Kelthane, which is a miticide used on flowering perennials.
Butterflies and hummingbirds are attracted to phlox nectar, making phlox an excellent choice for a butterfly garden. Two beautiful species of butterflies that require the nectar from phlox plants are the eastern black swallowtail and the tiger swallowtail, according to Iowa State University’s Reiman Gardens.