That is not mascula ssp hellenica because if it were it would be a herbaceous plant that dies back yearly. What you are showing is rather P. rockii (or a Gansu Mudan cultivar), which is a shrub that has flowers with those dark blotches in it. They grow quite well in the UK.

There’s a Gansu Mudan specialist in your country named Will McLewin ( http://www.phedar.com ). He has written a book on them, so I’ll give you what he says:

The ideal situation for Gansu Mudan is in deep, rich, open loam draining well but not particularly fast in a fairly sunny position with brisk air circulation. Obviously the more extreme the deviation from the ideal the less well plants will grow without remedial measures, but on the whole any half-decent site will do. So, in very loose, sandy soil add plenty of organic matter especially leaf-soil to provide nutriment and aid moisture retention; in heavy sticky clay add grit and again organic matter to aid drainage and encourage root growth.

Feeding and pruning

The starting point in considering these two activities is that in the wild nobody feeds and nobody prunes plants. Consequently if you have an urge to do either then the first question is not what or when or how but why.

Gansu Mudan grow best in sunny situations. The new growth ripens well and flower buds develop more reliably. However they cope very well with shade provided that the soil is at least decent and there is adequate moisture. Many wild plants of P. rockii grow in quite severe shade and experience dry conditions. In hot, humid and rainy places, especially those at low altitude, Gansu Mudan may suffer leaf diseases in August and September. In high, cold, shady and wet places, it would be better to grown them on slopes facing the sun. In extremely dry and hot places, flowers and leaves are likely to suffer and it would be better to grow Gansu Mudan on shady slopes or on the shady sides of buildings or big trees.

Transplanting

It is frequently said that “peonies do not like being moved”. This is nonsense. Apart from pointing out that anthropomorphism about plants is rarely other than misleading, if the plant can be moved without damage of any kind then obviously it can be moved anywhere and any time. Avoiding damage of any kind would require moving the entire plant and its immediate landscape intact, which is impracticable. What usually happens is that some, often most, of the root structure is damaged or broken off when the plant is moved and so the ability of the root system to sustain the state, condition and growth of the branch and leaf structure is impaired. Bear in mind that even when there is no obvious sign of root damage most of the very fine active capillary roots will have been lost. Two things follow from this. The more the root system is damaged the more die-back of branches is likely and also the longer the plant will take to recover its previous state. As a general rule the root system underground is as extensive in size as the visible plant above ground and probably more densely branched, so digging up a large Gansu Mudan will usually inevitably result in the loss of much of its root and almost all of its active fine root. If this takes place during the time of active growth then a significant proportion of the branches and leaves should be removed and the replanting done at once. With care, and if circumstances demand it, Gansu Mudan in flower can be successfully transplanted bare-root. In this case speed and watering before and immediately after moving is advisable.

All that said, the best time for transplanting is late Summer, when leaves are changing colour and beginning to cease activity and before new fine root growth begins. At this time plants can survive for weeks out of the ground even with substantial root loss. Of course such treatment is not desirable but it demonstrates that to move them is not particularly risky. If immediate replanting in the desired position is not possible then temporary planting or heeling in or covering the roots with, for example, damp moss will be beneficial. At the very least store bare-rooted plants in a cool, shady place before replanting. Only relatively small plants move ‘as if nothing had happened’ but even very large plants, twenty or more years old can be moved fairly easily, albeit with a year or two to recover and with some die-back. For the first year after transplanting removing flower buds as soon as they begin to develop and paying particular attention to watering and feeding will aid recovery. In particularly hot weather after transplanting it would be beneficial to provide shade and possibly spray with water to prevent leaves drying off.