UT Gardens August 2010 Plant of the Month: Hybrid Summer Phlox

UT Gardens August 2010 Plant of the Month: Hybrid Summer Phlox

Posted: Wednesday, August 25, 2010 8:01 pm

Submitted by Dr. Susan Hamilton, Director of the UT Gardens

 
Summer Phlox (Phlox paniculata) has long been a perennial staple in the summer garden. It typically grows tall, anywhere from 3 to 5 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 cultivars, along with ‘Eva Cullum’ and ‘Bright Eyes’ (both of which are pink with a red eye), and ‘Franz Schubert’ (a lilac cultivar). 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 is bringing an array of fantastic new hybrids that tout numerous wonderful characteristics.
 
First among their admirable traits is 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 and put on a colorful show. Next, they have a shorter, stockier growth habit growing to just 16” tall and 20” wide, and numerous colors are also available. 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 a moist but well-drained soil. A good 2- to 3-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.
 
Here’s a list of hybrid phlox that we have grown in the UT Gardens and have found to be great performers for our Tennessee landscapes: 
 
Cocktail Series: ‘Watermelon Punch’; ‘Pina Colada’; ‘Cosmopolitan’; ‘Peppermint Twist’; ‘Purple Kiss’; and ‘Tequila Sunrise’
 
Flame Series:  ‘Pink’; ‘Lilac’; and ‘Purple’
 
 
 
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 http://utgardens.tennessee.edu/  and http://westtennessee.tennessee.edu/ornamentals/ for more information.
Posted 8.25.10

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