Complete Guide to Planting and Growing Herbaceous Peonies

No garden feels complete without these majestic perennials, which burst into sumptuous bloom each May and June. True perennials, herbaceous peonies can live fifty years or more, becoming more impressive with age. They're easy to grow and reward you with armloads of cut flowers and a spectacular garden display. Use them as striking specimens, mix with other perennials, or line a walkway or driveway. Early, mid, and late-season varieties extend the bloom period, and many are fragrant. Peonies thrive in Zones 3–8; in the South, they flower in Alabama but prefer cooler Zone 8 areas. Southern gardeners should choose early-blooming singles for best results.

Pronunciation

Pronunciation: pay-oh'-nee-ah

Light and Watering

Plant in full sun, except in the South and warmest western regions where afternoon shade helps flowers last longer. Provide an inch of water weekly throughout the growing season.

Soil, Fertilizer, and pH

Rich, well-drained soil with ample organic matter is ideal. In very acidic soil, add lime at planting. Position roots with eyes (pink or white buds) facing up, covered by 1–2 inches of soil in the North, no more than 1 inch in the South. Critical: Planting too deep prevents blooming—don't mulch over crowns. First-year blooms may be sparse; plants typically need a few years to settle in and flower heavily. An annual side-dressing of 1 inch of compost or aged manure is sufficient—no other fertilizer needed. Many varieties, especially doubles, require staking to prevent heavy blooms from flopping. Install supports as new growth emerges in early spring.

Pests and Diseases

Few insects trouble peonies, but botrytis (a fungal disease) can be problematic in wet seasons. Stems develop cankers or blacken at the base, foliage shows dark patches, and buds fail to open. Good culture and sanitation help prevent issues: ensure drainage and air circulation, avoid crowding, remove affected foliage promptly, and deadhead religiously. Cut all foliage to just below soil level after a killing frost and remove debris—don't compost. If botrytis appeared previously, add a thin sand layer around crowns and spray emerging shoots with Bordeaux mix or lime sulfur. Fungal spores overwinter at plant bases; spring rains splash them onto new growth. Removing debris and covering soil with sand prevents reinfection.

Phytophthora blight may also appear but is hard to distinguish from botrytis. If suspected, consult your USDA Extension agent—this disease is usually fatal, requiring infected plant removal and soil replacement.

Powdery mildew can affect peonies in summer. The white coating on leaves rarely impacts plant vigor. Prevent by planting in full sun with ample air circulation.

Cutting Flower Buds for Later Enjoyment

To enjoy blooms later in summer, cut buds just before opening on 6-inch stems. Lightly moisten a large resealable plastic bag, place buds inside, seal, and refrigerate (not freeze). When needed, float buds in shallow water. When ⅓ open, lift, trim stem to 1½ inches, and refloat.

Companion Planting

Peonies pair beautifully with roses and clematis. Allow space for air circulation. White peonies glow against evergreens. Spring bulbs like Crocus vernus or Scilla siberica create lovely contrast at the base of emerging reddish peony stems.

Encouraging Reflowering

Many varieties produce side buds that open after the terminal bloom—deadheading helps. Cut stems below spent blooms, leaving foliage. For exhibition-sized flowers, remove side buds as they form, keeping only the terminal bud.

Dividing and Transplanting

Herbaceous peonies rarely need dividing and may resent it. If moving is necessary, divide in fall after foliage dies back completely. Each division needs 3–5 eyes and will take a couple of years to flower.

End-of-Season Care

Cut back foliage in fall and remove from the garden to discourage overwintering pests. Mulch new plants with evergreen boughs or salt marsh hay after the ground freezes.

Calendar of Care

Early Spring

Water well if spring rains are insufficient. Side-dress with compost or aged manure. If botrytis was present last season, apply a thin (¼-inch) sand layer around plants and spray new shoots with Bordeaux mix or lime sulfur. Install stakes now.

Mid-Spring

Monitor for botrytis and treat promptly, removing diseased tissue. Train growth through supports. Remove side buds if exhibition blooms are desired.

Late Spring

Deadhead religiously and remove all fallen petals and blooms.

Summer

Maintain 1 inch of water weekly.

Fall

Cut stems to soil level and remove debris. Divide plants if needed. Mulch new plantings with evergreen boughs or salt marsh hay after ground freezes.