Mt Cuba Center
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Trial Garden

Phlox amplifolia

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Phlox amplifolia is an exciting species that had not been used in horticulture prior to our evaluation. The noticeably hairy foliage grows approximately 2′ tall and is relatively immune to powdery mildew. In June, it produces large, airy inflorescences of pink flowers that rise 1-2′ above the mass of foliage and continue to bloom for about six weeks. However, the most interesting thing about this species is its rhizomatous habit. Largeleaf phlox produces underground runners that slowly spread outward to form a large mass, similar to the way bee balm (Monarda spp.) grows, though not as aggressive. Such a habit could be very beneficial in meadows and naturalistic plantings where largeleaf phlox can be allowed to meander. Much of the outstanding garden performance of this species likely comes from its ability to grow in drier soils, especially compared to Phlox paniculata which requires consistently moist conditions. In the wild, Phlox amplifolia can be found growing in dry-mesic upland sites from Indiana south to Alabama, and from Arkansas east to Virginia. Further selection and perhaps hybridization of Phlox amplifolia could lead to more adaptable summer-blooming phlox for the garden.


  • Rating
  • Common Name
    largeleaf phlox  
  • Bloom Period
    early June—mid-July 
  • Peak Bloom
  • Size
    44” x 36” 
  • Fragrance
    None Observed 
  • Powdery Mildew Resistance