To find the most heat and humidity resistant natives and ornamentals, I head straight for Niche Gardens. Located in North Carolina and specializing in nursery-propagated wildflowers, natives, perennials, and grasses, Niche is an absolute gem and my garden is stuffed with their plants. They also offer a small selection of unusual shrubs and trees.
White 'Delta Snow' phlox is the best phlox for southeastern gardens. It's more drought resistant than most phlox and doesn't mildew.
'Delta Snow' phlox is the toughest, most mildew resistant phlox I've ever grown. Purchased from Niche, it gently seeds around my garden giving me sturdy seedlings I can pass on to lucky friends. It is impervious to heat and humidity and keeps happy company with other powerhouse varieties of phlox they sell.
Home to many natives such as Short's Aster, an outrageously tough plant for bright dry shade, Niche offers the best plants for southeastern gardens. Plants are available online or at the nursery. Every plant sold at Niche is pesticide-free, which is still a rarity. You'll never have to worry that your new plants are poisoning the very pollinators they attract. What you'll receive instead is the carefully packed, robust, healthy plant you were hoping for when you ordered.
Spigelia marylandica, a native wildflower, purchased from Niche.