Phlox are some of the most popular perennials in today’s garden. This North American genus comprises over 60 different species, but our trial focuses on seven of the most garden-worthy species that are native to the eastern United States. With over 100 selections, phlox represents Mt. Cuba Center’s largest evaluation to date. Garden phlox (Phlox paniculata) is by far the most popular species of the group, and as such makes up the bulk of our trial. Garden phlox has been loved by gardeners for generations. These wonderful perennials are grown for their large and colorful flowers, often accompanied by a pleasant perfume, that provide unrivaled beauty in the summer garden. Phlox are also great for attracting butterflies, and while there are many reasons people enjoy these plants, they are not without their problems. Powdery mildew is a significant disease that affects many types of phlox, especially the ever-popular garden phlox (Phlox paniculata). For this reason, Mt. Cuba Center has set out to determine which phlox are the top-performing, most disease resistant selections for the mid-Atlantic region, while also examining the horticultural value of underutilized species and new selections not yet available to gardeners.