One of the best perennial flowers for blooming from mid-summer to fall is the tall garden phlox. Phlox paniculata and other tall species have colorful blooms, and depending on the selections, are great pollinator plants. However, they can be plagued with powdery mildew disease during our humid summers.
The solution is variety selection. Mt. Cuba Center is a Delaware public garden that has been trialing various perennial flower varieties in their zone 6 to 7 gardens for years. One trial they did a few years ago was on the tall garden phlox varieties. Mt. Cuba uncovered some of the best phlox varieties for home gardeners.
Phlox 'Jeana' is hands down the best lavender-pink flower colored variety. It produces tons of flowers from July to mid-September, on a 3- to 5-foot tall plants that are drought tolerant, grow in part shade and are powdery mildew resistant. An added bonus is 'Jeana' had the most butterflies of any phlox variety in the trial.
The top rated phlox that is not lavender-pink flowered was 'Glamour Girl'. It has coral-pink flowers on 3 foot tall plants that bloom July through August. It's a vigorous grower with lush foliage and little powdery mildew. If you like white flowers, try 'Delta Snow'. This paniculata type has white flowers with a pink center. It is one of the best varieties for powdery mildew resistance.
Finally, for a phlox from a different species, try the lavender colored Phlox amplifolia. It's unique for its 2 foot height, ability to grow in dry soils and its proclivity to spread by underground rhizomes making it a great meadow plant.
