Tree Peonies
Planting Tree Peonies
Afraid to take the plunge?
Where should I plant my Tree Peony
Tree peonies are extremely hardy and will survive almost anywhere, in both sun and shade but are happiest in a south west to north facing aspect. They prefer an airy, reasonably open situation as air movement around the plant helps keep it healthy. However, avoid a completely exposed position where storm damage may cause flowers to snap
Soil
Generally speaking tree peonies prefer a fertile yet, reasonably well drained soil which is neutral to slightly alkaline. Clay, chalky and sandy soils are all fine so long as they don’t become too dry in the summer or very wet in the winter.
Receiving your Tree Peony
Bare root tree peonies will be sent when dormant during the autumn. Unpack straight away. If you are unable to plant for a few days, gently place bare root tree peonies into a pot with some moist potting compost and keep in a cool place such as a shed. Containerised plants will be sent out all year and can be kept in their pots as long as necessary, but take care they do not dry out.
Planting
Bare root tree peonies are always planted from autumn to early spring, but not if the ground is frozen. Containerised plants can be planted all the year round, but if planted in late spring or summer will need to be watered regularly. Be careful to not overwater.
Dig a large planting hole incorporating some bonemeal or general fertiliser into the soil. Add some well rotted garden compost or manure if you wish. Plant bare root tree peonies deeply. Grafted types should be planted so that the graft union is at least 8cm below the soil surface. This will encourage the tree peony to make fresh roots and basal shoots. Lutea-Hybrids are divisions, and these should be planted so that the topmost roots are approximately 8cm below the soil surface.
Containerised plants of all types should be planted slightly deeper than the soil level in the pot. Water well after planting and during the following months.
Subsequent cultivation
Usually a tree peony will grow away producing large handsome leaves and often some new shoots from the base. However, the main stem may not produce a shoot from the tip. Depending on the size of the plant you buy, flowering can happen any time from the first year to 4 years from planting. Sometimes a plant will appear to make little growth, if any, in its first season, and please note, that no new shoot growth generally happens after the end of May. Occasionally the main stem may die back a little. Although this might look alarming, wait until the next spring when vigorous growth should resume from the lower part of the stem or even from below soi level. On grafted plants look out for suckers from the rootstock and cut these off at ground level if they appear. The foliage is quite different from that of the tree peony and is easily identified.
Feeding
Tree peonies are heavy feeders and respond well to a generous, early autumn top dressing of blood, fish and bone, or a slow-release fertiliser. A high potash content encourages flowers to develop. A light sprinkling of a general fertiliser can also be applied in spring if you wish.
Pruning
Tree peonies respond well to pruning. You should aim for a broad, multi-stemmed shrub of up to 120-150 cm in height which will not need staking. In February, just as the growth buds are swelling, trim off any old dead wood. You will often find that the new shoots are coming from lower down the stem, leaving a small dead spur. Whole branches will sometimes die which is completely normal. These should be pruned back to a live bud or to just above ground level. With a young plant, the only pruning needed is to remove dead wood during the first 2 years to help get the plant established. After this, if your plant forms a good shape, no regular pruning is needed other than cutting back to a live bud. However, if your plant ends up with few stems and is poorly shaped, then prune hard. You may see buds at the base of the stem or shoots coming from below the soil. Prune back to these or down to 15cm or less from the ground. Even if you can’t see any basal buds, new ones will form. The best time to prune is early Spring, although this may mean you sacrifice some flowers in the coming year. You can also prune directly after flowering but regrowth may not occur until the following Spring. If you have or inherit an older tree peony which has never been pruned, it can be transformed and rejuvenated by applying the following technique. Prune one main stem each Spring, cutting it down to about 15cm. It takes courage, but is almost invariably successful in the long term.
Moving a Tree Peony
There’s no need to worry about moving even a large, mature tree peony. Just dig it up and move it during early autumn as you would any other woody deciduous shrub.
Tree peonies can be grown successfully for several years in a large container at least 30cm in diameter. When planting, it is important to use a soil based compost such as John Innes No. 3. Always be very careful not to overwater.
Peony wilt
Tree peonies rarely suffer problems from pests and are unpalatable to rabbits and deer. The only disease you are likely to encounter is peony wilt (Botrytis). This may appear in early spring, usually before flowering. Good hygiene and cultural practices are the key to preventing and dealing with fungal attack. Maintain a good air flow around the tree peonies by not overcrowding them with other plants, particularly at ground level. If any stems collapse with Botrytis, or if any leaves become spotty, remove them immediately this will help the spread of infections. Fungal spores of peony wilt over winter on old foliage, it is important to pick up and burn old leaves in the autumn.