Growing Tree Peonies (Paeonia suffruticosa): A Complete Guide

Tree peonies are magnificent, long-lived woody shrubs that deserve a place in every garden. Some varieties reach 4–5 feet tall and produce fragrant flowers up to 10 inches across. They thrive in regions with cold winters and hot summers, performing beautifully in the Northeast and Midwest, and are hardy in Zones 4–8. Zone 9 gardeners can force dormancy by removing all foliage in November, leaving woody stems, withholding water and fertilizer, and hoping for flower bud formation.

Patience is essential—tree peonies may take 3 years to establish and bloom. New plants may not reach their full potential for several seasons. They're also slow to break dormancy the first spring after planting; a plant that looks dead while neighbors leaf out will awaken soon enough.

Light and Watering

Light afternoon shade protects flowers—in China and Japan, small parasols shade the plants. Choose a site protected from drying winds. Once established, tree peonies are very drought-tolerant. Do not overwater and avoid planting near automatic irrigation. Wait until soil dries to 4 inches deep, then water deeply. Overwatering kills roots and is a common cause of failure.

Soil, Fertilizer, and pH

Well-drained soil with neutral to slightly alkaline pH is ideal. In acidic soil, add lime at planting. Plant at the depth indicated by the green plastic ribbon on the main stem, removing the ribbon afterward. If the ribbon is missing, plant the graft union (visible as a bulge on the main stem) 4–6 inches below soil level to encourage the scion to form its own roots. Top-dress with 1 inch of compost or aged manure in spring. A foliar feeding with fish emulsion during the growing season is beneficial.

Pests and Diseases

Rarely, a boring insect may create a hole in a woody stem. Try killing the larva with a thin wire or remove the affected section. Like herbaceous peonies, tree peonies can develop fungal diseases causing black leaf spots and shoot wilting. Remove diseased foliage promptly and clean up all fallen plant parts in autumn. If fungal issues persist, spray with fungicide early in spring, repeating for several weeks. Deadhead diligently and don't allow fallen petals to accumulate on the plant or ground.

Companion Planting

Hellebores, Alchemilla, Leucojum, Epimedium, and Siberian irises complement tree peonies beautifully. If plants become leggy, underplant with spring-flowering bulbs.

Pruning

Never prune tree peonies to the ground like herbaceous types. Remove damaged or broken stems after leaf-out. On mature, vigorous plants, thin the center to encourage flowering on taller stems and improve air circulation. Tree peonies are grafted onto herbaceous peony roots; occasionally a shoot from the rootstock emerges at the base—remove these immediately.

Dividing and Transplanting

Tree peonies don't require division, and it's often impossible. Young plants may be moved when dormant; dig with as much soil around roots as possible.

End-of-Season Care

Remove all foliage after a killing frost, including leaf petioles; discard away from the garden, not in compost. Mulch new plants, and in coldest areas, wrap with burlap or similar material for winter wind protection.

Calendar of Care

Early Spring

Top-dress with 1 inch of compost or aged manure. Watch for fungal disease and treat as needed. Remove any rootstock shoots.

Mid-Spring

Some varieties need support for heavy flowers. Thin crowded interior foliage to improve air circulation.

Late Spring

Don't overwater. Deadhead spent blossoms diligently and remove old flowers and petals from the garden.

Summer

Water only when soil dries to 4 inches deep, then water deeply. Foliar feeding with fish emulsion is appreciated.

Fall

Do not prune back—they're woody shrubs. Remove all foliage after frost (don't compost). Mulch new plants and those in colder zones; wrap with burlap if cold winter winds are expected.