Selecting the right peony (Paeonia spp.) for your garden begins with understanding the fundamental botanical requirements of the plant and how they interact with your specific regional climate. The two primary types grown in gardens are herbaceous peonies, which die back to the ground in winter, and tree peonies, which are woody shrubs. Your success hinges on matching a variety's chilling needs, heat tolerance, and disease resistance to your USDA Hardiness Zone and local conditions.
Peonies are temperate plants that require a period of winter dormancy with sustained cold temperatures, known as chill hours, to initiate spring growth and flowering. Most herbaceous peonies thrive in USDA Zones 3-8, requiring at least 30 consecutive days of winter temperatures at or below 40°F (4°C). Tree peonies are generally suited to Zones 4-9. In regions with mild winters (Zones 9-10), choosing low-chill varieties or artificially inducing dormancy becomes critical. Conversely, in the coldest regions (Zones 2-3), selecting extremely cold-hardy cultivars and providing winter mulch is essential for protection.
Northeast & Upper Midwest (Zones 3-7): This climate is ideal for most herbaceous peonies. The long, cold winters satisfy dormancy requirements perfectly. Focus on classic varieties like the resilient 'Sarah Bernhardt' (pink double) or the early-blooming 'Festiva Maxima' (white with crimson flecks). Tree peonies also perform well here but benefit from light winter protection in Zone 4.
South & Southeast (Zones 7-9): The primary challenges are insufficient winter chill and high summer heat/humidity, which can promote fungal diseases like botrytis. Seek out early-blooming herbaceous varieties that flower before the peak heat, such as 'Kansas' (vivid red) and 'Coral Charm' (coral-pink). The species Paeonia tenuifolia is also notably heat-tolerant. Tree peonies often outperform herbaceous types in the Upper South due to their woody structure.
West & Pacific Northwest (Zones 7-9): This region offers diverse microclimates. In cooler coastal areas like the Pacific Northwest, nearly all peony types excel. In hotter, drier interior valleys, select heat-tolerant varieties and ensure consistent irrigation. The Itoh (intersectional) hybrids, a cross between herbaceous and tree peonies, are excellent for their strong stems and disease resistance across these zones.
Southwest & Desert Regions (Zones 8-9): Success depends on providing adequate chill and shelter from intense afternoon sun. Planting in partial shade and using winter mulch can help keep root zones cool. Early-blooming and single-flowered varieties that allow for better air circulation are advantageous. Some specialty nurseries offer "low-chill" peonies specifically bred for these climates.
Beyond climate, site selection is paramount. Peonies are long-lived perennials that demand well-drained, neutral to slightly alkaline soil. Crown rot from waterlogged soil is a primary cause of failure. Ensure they receive at least 6 hours of full sun for optimum flowering, though light afternoon shade is beneficial in very hot regions. Proper planting depth is non-negotiable; herbaceous peony eyes (buds) should be no more than 2 inches below the soil surface. Planting too deeply is a common reason for a peony's failure to bloom.
