Peonies are garden flowers known for their substantial, often fragrant blooms and remarkable longevity. With appropriate care, these hardy perennials can flourish for many decades, some even exceeding 100 years. Their varied forms contribute to their enduring popularity.
Types of Peonies
Herbaceous peonies are common, featuring bushy growth that dies back to the ground each winter, re-emerging in spring. They grow 2 to 3 feet tall and bloom for 7 to 10 days in late spring to early summer. These cold-hardy plants thrive in USDA Zones 3 through 8 and require a chilling period to produce flowers.
Tree peonies are woody shrubs native to China, maintaining stems above ground year-round. They grow 4 to 7 feet tall and 4 to 5 feet wide, with flowers up to 10 inches across. Their bloom period is longer, up to 14 days, and they do not require intense chilling.
Intersectional (Itoh) peonies are hybrids combining traits from both herbaceous and tree peonies. They exhibit large, showy flowers and a diverse color palette, including yellows and oranges not found in herbaceous types. Their foliage dies back in winter like herbaceous varieties. These hybrids have sturdy stems that generally do not require staking and an extended bloom period of three to four weeks as new buds open.
Planting Peonies
Plant peonies in the fall, ideally six weeks before the ground freezes, allowing roots to establish. While spring planting is possible, fall planting yields better, more robust growth.
Peonies require ample sunlight, ideally six to eight hours of direct sun daily, for abundant blooming. The soil should be well-drained to prevent root rot, with a neutral to slightly acidic pH (6.5 to 7.5). Before planting, amend the soil with compost or organic material, loosening it 12 to 18 inches deep.
When planting herbaceous peonies, position the root so the buds, or “eyes,” are 1 to 2 inches below the soil surface; deeper planting can inhibit flowering. For tree peonies, position the graft union 4 to 6 inches below ground. Space plants 3 to 4 feet apart for mature growth and good air circulation, which prevents disease.
Caring for Peonies
Once established, peonies are low-maintenance. They require about one inch of water per week, especially during dry spells. Water deeply at the base, avoiding overhead watering which can encourage fungal issues. While drought tolerant, consistent moisture supports plant vigor.
Fertilize sparingly; an annual application of compost or a balanced fertilizer after blooming is usually sufficient. Excessive nitrogen promotes leafy growth at the expense of flowers, so a balanced approach is recommended. Large, heavy blooms can cause stems to bend, so provide support with stakes or hoops early in the growing season to maintain an upright form.
Deadheading spent flowers helps the plant conserve energy and improves appearance. In fall, after foliage dies back from frost, cut herbaceous peony stems to the ground and remove all plant debris to prevent overwintering diseases. Mature plants typically don’t require winter mulching, but a light layer can be applied for the first winter in cold regions, removed promptly in spring.
Common Peony Challenges
Peonies can face challenges, such as failure to bloom, which stems from several factors. Planting the “eyes” too deeply or insufficient sunlight (less than six hours) are frequent causes. Immature plants may also produce limited or no blooms in their first few years.
Ants are often seen on peony buds, attracted to sweet nectar. They are harmless and typically disappear once flowers open.
Peonies can be susceptible to diseases, particularly in humid conditions or areas with poor air circulation. Botrytis blight, also known as gray mold, is a fungal disease causing brown, mushy spots on buds, leaves, and stems, often leading to wilting. Powdery mildew appears as a white, powdery coating on foliage, especially in shaded, crowded areas. To prevent these issues, ensure adequate spacing, avoid overhead watering, and remove infected plant parts, disposing of them away from the garden to prevent spread.