Summer Phlox (Phlox paniculata) has long been a perennial staple in the summer garden. It typically grows tall, anywhere from three to five feet, blooms in July and then – much to our dismay – it succumbs to powdery mildew fungal disease. One of the most highly touted of the standard varieties is “David,” a beautiful white cultivar. Also popular is its offspring, “David’s Lavender.” They are consistently ranked among the most mildew-resistant varieties.

Because  it is prone to disease and it needs staking, this tall perennial has seen its popularity wane over the years. However, good hybridizing and breeding are bringing an array of fantastic new hybrids that tout wonderful characteristics.

The new hybrids have a long blooming period from July through the end of summer. They are also self-cleaning, which means that no deadheading is required because as old flowers fade and wither away new ones continue to open up.  They also have a shorter, stockier growth habit growing to just 16 inches tall and 20 inches wide, with numerous colors available to choose from. Because of their long blooming habit and shorter height, they can be used in the foreground of a planting bed or even in containers. Another wonderful characteristic of these new hybrids: mildew resistance.

For best performance, plant summer phlox in a site that enjoys full-sun to partial shade and in moist but well-drained soil. A good two- to three-inch layer of a fine mulch around these perennials will help retain soil moisture and reduce the incident of weeds. Apply liquid feed or an all-purpose fertilizer the first growing season while plants are getting established. Be sure to follow label directions. At season’s end, a good maintenance tip is to cut off dead flower heads and stalks.

Dr. Susan Hamilton is a faculty member in the University of Tennessee Department of Plant Sciences and director of the UT Gardens. The Gardens are a program of the UT Institute of Agriculture and are known for conducting research and plant trials on herbaceous and woody ornamental plants, for various seasonal horticultural displays, and for numerous educational programs. The UT Gardens in Jackson and Knoxville are both open to the public. See utgardens.tennessee.edu/ and westtennessee.tennessee.edu/ornamentals/ for more information.