Site and soil
- Tree peonies are very hardy. However, the foliage and flower buds can be damaged by late frost so avoid frost pockets
- Choose a sheltered position to prevent branches being broken off by strong winds, especially when carrying large blooms
- Tree peonies prefer neutral, humus rich soils, but they will tolerate slightly acid or slightly alkaline soils
- Good drainage is essential. Where drainage is poor, consider planting in raised beds
- Ideally, plant in a sunny position. Tree peonies will tolerate light shade, but the plants may become straggly growing towards light
Tree peonies are ideally planted in the autumn, but winter or early spring planting is also suitable. Avoid planting in late spring and in summer. The hot and dry weather can hinder the plants’ establishment.
Tree peonies grown on their own roots should be planted at the same soil level as they were in the container. If bare root, look for the nursery soil mark on at the base of the stems.
However, most tree peonies offered for sale, especially named cultivars, are grafted on herbaceous peony rootstock. Look for the graft union (visible as a slight bulge) close to the base of stem. When planting, the graft union should be about 15cm (6in) below the soil level. Deep planting encourages the grafted plant to form its own roots, which reduces suckering from the herbaceous rootstock and prevents the rootstock becoming dominant.
Prepare the planting area by incorporating organic matter such as leafmould, garden compost or well-rotted manure.
Water well during the establishment period.
Feeding and mulching
Especially on lighter soils, in spring apply a light top dressing of a general balanced fertiliser around the base of the plant. Avoid using high nitrogen fertilisers.
In late winter or early spring apply about 10cm (4in) layer of organic mulch such as leafmould, garden compost or well-rotted manure to the main rooting area (immediately under the canopy of the plant). Keep the base of the stems free from mulch.
For a limited period of time tree peonies can be grown in large, deep containers at least 30cm (1ft) in diameter. Top dressing with fresh compost in spring and regular feeding during the growing season is essential for the plant to thrive container cultivation. However, after about five or six years the vigour often declines. To revive an ailing tree peony, plant it out into the in border; they usually recover well.
For container cultivation use a soil-based compost such as a John Innes No 3 with added grit to improve drainage. Water regularly but ensure that the compost does not remain permanently soggy.
Though fully hardy in the open ground, the roots of containerised plants may be damaged by hard frost. To reduce potential damage move containerised plants into a more sheltered spot, stand it off the ground on bricks and wrap the container in bubble wrap or hessian sacking.