Your USDA hardiness zone determines your frost dates, which in turn dictate your planting schedule and which flowers will thrive. Here is a zone-by-zone overview.
Focus on fast-growing annuals: zinnias, cosmos, sunflowers, marigolds. Start seeds indoors to maximize the short season. Peonies and delphinium excel as perennials. Cool-season flowers like sweet peas and snapdragons bloom well in the mild summers. Succession planting is essential for sustained harvest.
The sweet spot for the widest range of cut flowers. Spring crops (tulips, daffodils, ranunculus, sweet peas, snapdragons) transition into summer flowers (dahlias, zinnias, lisianthus, celosia). Perennials like peonies and delphinium perform well. Lift dahlia tubers in fall.
Plant cool-season flowers in fall for early spring blooms: sweet peas, snapdragons, larkspur, stock. Summer heat limits some flowers, but zinnias, celosia, sunflowers, and amaranth thrive. Dahlias can overwinter in zone 8 with mulch. Ranunculus and anemones planted in fall bloom in early spring.
Year-round growing is possible. Fall and winter are the prime growing seasons for cool-season crops. Peonies and delphinium struggle without winter chill. Focus on heat-tolerant varieties and grow cool-season flowers during the mild winter months. Tulips need pre-chilling.