It’s been nearly three years since I set off on a late-August morning for Cashiers, North Carolina, for a visit to a meeting of the Carolinas Dahlia Society, but I’ll never forget the enthusiasm and comradery of the members that day, nor the buckets of glorious blooms they brought with them.
Dahlias, a group of tender, tuberous plants, begin to flower just as the growing season starts to wane, extending the garden’s splendor when most daisies, daylilies, and other summer perennials have finished their show. Typically, they provide the vivid colors that make fall gardens so satisfying and are excellent companions for the asters, salvias, and sedums, which also bloom this time of year.
Since their initial introduction in the late 1700s, dahlias have been selectively hybridized into a remarkable group of ornamentals. While most plants have just two sets of chromosomes, dahlias have eight, allowing a much greater variation among hybrids.
Cultivars range in size from just inches to towering heights and flowers comprise a wide array of sizes, shapes, and colors. Plus, once dahlias begin to bloom, they’re the epitome of cut-and-come-again. The more you pick, the more they flower, with blooms opening nonstop until frost.
Not all dahlias are equal, however, especially in the hot and humid growing conditions of Upstate gardens. Careful selection of heat-tolerant dahlias is critical to success in the Carolinas. Native to the high mountain plateaus of Mexico and Guatemala, most dahlias prefer warm days and cool nights.
Heirloom dahlias that are heat-tolerant include ‘Bishop of Llandaff’, ‘Juanita’, ‘Kidd’s Climax’, ‘Prince Noir’, and ‘Thomas Edison’. Among newer cultivars, look for ‘Ben Houston’, ‘Elsie Houston’, ‘Hilltop Glo’, ‘Island Dynasty’, ‘Kenora Firefighter’, ‘Otto’s Thrill’, and ‘Zorro’. The best single-form flowers, which mingle easily in both borders and containers, include ‘Alpen Cherub’, ‘Honka’, and ‘Marie Schnugg’.
For a comprehensive list of recommended plants, visit the website of the Dahlia Society of Georgia.