South Carolina’s long and diverse growing season allows for planting nearly year-round. Success depends on matching a flower’s temperature tolerance to your specific location and the current month. Gardening in the Palmetto State requires understanding the distinct cool and warm periods that dictate which plants will flourish, ensuring color from early spring until late fall.
Understanding South Carolina’s Planting Seasons
The variable climate across South Carolina is the primary factor influencing planting decisions, dividing the state into several USDA Hardiness Zones. These zones range from 7b in the cooler, higher elevation Upstate region to a subtropical 9b along the immediate coast and Sea Islands. This wide range means the average last spring frost date can occur as early as late January in the Lowcountry, but not until April in parts of the Upstate. This variation creates two primary planting windows defined by temperature and frost tolerance. The Cool Season relies on hardy and half-hardy annuals that can survive light frost and mild winter temperatures, while the Warm Season depends on tender annuals that thrive in the state’s intense, humid summers.
Flowers for the Cool Season
Cool-season flowers prefer the mild temperatures of spring and fall and can withstand light freezes. These varieties are typically planted in the early spring, before the summer heat arrives, or in the fall for winter and spring color.
Pansies (Viola x wittrockiana) and Violas (Viola cornuta) are the favorites for cool-season color in South Carolina. These hardy annuals can be planted as transplants in late September through October, providing continuous blooms through the winter and into the early summer. They thrive in temperatures between 40 and 60 degrees Fahrenheit, often surviving light snow or frost events with minimal damage.
Snapdragons (Antirrhinum majus) are another excellent choice for the cooler months, prized for their vertical flower spikes. Gardeners should start snapdragon seeds indoors approximately 8 to 10 weeks before the last expected spring frost. Once established, these half-hardy plants can be set out in the garden a few weeks before the final frost, as they tolerate cooler soil temperatures.
Dianthus, often called Pinks, are half-hardy annuals that produce masses of fringed, fragrant blooms. They are typically planted from transplants in early spring and will provide color until the intense heat of summer causes them to decline. Calendula (Calendula officinalis) is a hardy annual that can be direct-sown in early spring once the soil temperature reaches 60 degrees Fahrenheit. Calendula prefers mild temperatures and may stop blooming during the hottest part of summer, but it will often resume flowering when fall temperatures return. Ornamental cabbage and kale are also planted during this period, offering striking texture and color that intensifies after a light frost.
Flowers for the Warm Season
The warm season in South Carolina demands flowers with exceptional tolerance for intense heat and high humidity. These tender annuals must be planted only after all danger of frost has completely passed and the soil has warmed sufficiently, typically from late April through May in most regions.
Zinnias are a classic choice, thriving in the full, baking sun that characterizes a South Carolina summer. These flowers are exceptionally low-maintenance and are best started by direct sowing the seeds right into the garden bed after the last frost. They offer vibrant, long-lasting color and are resistant to the extreme heat and humidity.
Vinca (Catharanthus roseus), also known as Periwinkle, is highly valued for its ability to flourish in hot, dry conditions. This tender annual requires full sun and well-drained soil, making it a dependable option for beds that receive direct sunlight throughout the day. Its glossy, dark green foliage and five-petaled flowers offer a tidy, low-growing appearance.
Angelonia, or Summer Snapdragon, is another superb plant for summer heat, offering vertical flower spikes that mimic its cool-season namesake. Angelonia is a low-maintenance tender annual that performs best in full sun and tolerates short periods of drought once established. The newer, heat-tolerant varieties of Petunias, particularly the Wave and Supertunia series, are genetically selected to withstand the high temperatures and humidity of the South.
For areas that receive less than six hours of direct sun, Begonias are reliable warm-season options. Wax Begonias (Begonia semperflorens) handle partial shade to full sun with ease, while Tuberous Begonias prefer more consistent shade. Lantana is a sprawling, extremely heat-tolerant plant that requires full sun and is a favorite for attracting butterflies, producing clusters of small, brightly colored flowers from late spring until the first frost.