Peonies can grow in South Carolina, but success depends heavily on the location within the state and the specific variety chosen. South Carolina’s climate ranges from the cooler mountainous Upstate to the warmer Lowcountry and coastal plains, covering USDA Hardiness Zones 7b to 9. Successfully cultivating these classic, spring-blooming flowers hinges on meeting their biological need for a period of winter cold. Gardeners must make thoughtful selections and employ precise planting techniques to ensure the plants thrive and produce blooms.
Understanding Peony Chilling Needs
The primary challenge for growing peonies in the southern United States is the requirement for vernalization, measured in chilling hours. This process requires a plant’s flower buds to be exposed to a sufficient duration of cold temperatures to develop and bloom the following spring. Traditional herbaceous peonies require a sustained period of approximately six weeks below 45 degrees Fahrenheit, translating to about 400 to 1,000 chilling hours.
South Carolina’s Upstate region (Zone 7b) typically receives 800 to 1,000 chilling hours, making it the most hospitable area for traditional varieties. Conversely, the coastal Lowcountry (Zones 8b and 9) receives significantly fewer chilling hours, often ranging from 400 to 700. Insufficient cold exposure prevents peonies from setting flower buds, resulting in lush foliage but no blossoms, a condition often called “blindness.”
Selecting the Right Peony for South Carolina
Selecting the correct peony type is the most important factor for gardeners in the warmer parts of the state. The three main types—herbaceous, tree, and intersectional—have different cold requirements and heat tolerances.
Herbaceous peonies, such as common Paeonia lactiflora varieties, require the highest number of chilling hours. They are generally only reliable bloomers in the Upstate’s cooler Zone 7b. Even heat-tolerant herbaceous hybrids like ‘Coral Charm’ and ‘Blaze’ pose a risk of poor flowering in Zones 8 and 9.
Tree peonies (Paeonia suffruticosa) offer a better option for much of the state because they require a shorter period of cold dormancy. Unlike herbaceous types, tree peonies have woody stems that remain above ground year-round. This structure allows them to tolerate warmer winters, making them suitable for Zones 8a and 8b.
The most reliable choice for marginal climates, including Zone 9, is the Intersectional or Itoh peony. This hybrid cross between herbaceous and tree peonies combines the heat tolerance of tree peonies with the growth habit of herbaceous ones, dying back to the ground each winter. Itohs like ‘Bartzella’ or ‘Cora Louise’ are known for their vigor and ability to thrive even with limited winter chill.
Essential Planting and Site Preparation
Successful peony cultivation in South Carolina demands specific planting adjustments to maximize limited winter cold and mitigate summer heat. The planting depth for the root crown is the most important technique, especially in warmer zones. The “eyes,” or small pink buds on the root, must be positioned shallowly, ideally only half an inch to one inch below the soil surface. Planting any deeper insulates the buds, preventing them from receiving necessary winter chill and leading to a failure to bloom.
The planting location should provide at least six hours of morning sun, followed by protection from intense afternoon heat. Afternoon shade is important in Zones 8 and 9 to prevent foliage scorching and early heat-induced dormancy. The soil must be well-draining, slightly acidic to neutral, with a pH between 6.5 and 7.0. Amending heavy clay soil with compost improves drainage, which prevents root rot during warm, humid summers.