Mt. Cuba Center Research Report - Phlox for the Mid-Atlantic Region Mt. Cuba Center Phlox for the Mid-Atlantic Region - Page 2

INTRODUCTION Eastern Tiger Swallowtail on Phlox paniculata 'Jeana' P hlox represents a horticultural love affair that dates back to the earliest period of exploration and discovery in America. The showy and often fragrant flowers are now a staple of European and American gardens. Since their discovery centuries ago, horticulturists the world over have been selecting cultivars for improved horticultural traits. Now, with hundreds of phlox to choose from, today’s gardener can be overwhelmed with choices. While many of these selections claim to be disease resistant, their performance in the mid-Atlantic has never been truly examined. From 2015-2017, Mt. Cuba Center tested the performance of several different species of native phlox along with their related cultivars. The evaluation of 94 selections of eight sun-loving species is discussed first. This includes the ever-popular garden phlox (P. paniculata) beginning on page 3, followed by other sun-loving species like Carolina phlox (P. carolina) and smooth phlox (P. glaberrima) on page 9. Page 18 begins the results of our evaluation of two shade-loving species, woodland phlox (P. divaricata) and creeping phlox (P. stolonifera). While these evaluations are extensive, they do not include other native species like annual phlox (P. drummondii) or mat-forming species like moss phlox (P. subulata). Phlox is a large genus that includes more than 60 different species native to a variety of habitats throughout North America. Of those, 17 species can be found in the eastern United States. Phlox were initially described by European naturalists in colonial Virginia. The first such record comes from British naturalist John Banister who made detailed drawings of downy phlox (Phlox pilosa) and moss phlox (Phlox subulata) in 1680. The name Phlox, however, was not officially designated until 1737 by the father of modern taxonomy, Carolus Linnaeus. He coined the term Phlox, which is derived from the Greek word for “flame”, referring to the intense pink flower color of many species. Throughout the colonial era, new species of phlox were discovered and sent back to British gardeners. Philadelphia’s famed colonial botanist, John Bartram, is credited with sending the first specimens of Phlox paniculata to Europe in 1744. This species eventually became wildly popular in European and American horticulture. In fact, by 1917, a survey of American nurseries counted 584 named selections of Phlox paniculata. 2 Breeding and selecting of new cultivars of Phlox paniculata is still ongoing today. Much of this work is happening in the Netherlands where breeders are focused primarily on compact, disease resistant selections. However, the climate and disease pressures of Europe do not translate equally to the United States. In fact, Mt. Cuba Center found that many of the best selections for the mid-Atlantic region are plants that were selected in America rather than Europe. This includes most of the top performers whose origin stories often tell a narrative of chance discovery and humble beginnings. While the beauty of phlox has been admired for centuries, today’s gardeners are also falling in love with its ability to attract butterflies. As natural areas are lost to development, it is increasingly important to make our personal landscapes more productive for wildlife. Providing nectar sources for butterflies is one crucial step gardeners can take, and there are few plants better to use than phlox. For this reason Mt. Cuba Center evaluated butterfly preference as well as horticultural performance of Phlox paniculata (see pg. 16).