We have a magnificent specimen of Paeonia rockii here at Rosemoor to be found in the retaining beds just down the steps from the Visitor Centre. The flowering period may last only for two months but the fragile beauty of the silky petals gives high rewards and, when not in flower, the bold, architectural leaves are an attraction in themselves.
This plant has been flourishing at Rosemoor since Lady Anne Berry planted her first seedling plant in the Stone Garden in 1971. That first young plant was given to her by her dear friend Collingwood 'Cherry' Ingram, who collected and raised the seed himself.
Although plants subsequently known as Paeonia rockii were originally introduced to western cultivation in the 1920s, it was still little known in cultivation and, until the comparatively recent development of micro propagation techniques, was considered difficult to propagate. Happily this is no longer the case and this lovely plant is now quite widely available.
We have a number of good specimens in the garden at Rosemoor, the first being in the Retaining Wall beds immediately below the Visitor Centre in the Formal Garden. There are also still plants in the Stone Garden and in the adjacent Cherry Garden.
- Common name
- Tree peony
- Height & spread
- 2.2m (7ft) x 2.2m (7ft)
- Deciduous shrub
- Fertile humus-rich, well-drained soil, sheltered from drying winds
- Full sun or partial shade
- Fully hardy
This genus contains 30 or more species of herbaceous perennials and deciduous shrubs known as 'tree peonies'. They are found in meadows, scrub and mountainous regions from Europe to East Asia and in western North America.
They are very long-lived plants, with some cultivated plants over 100 years old. They have adapted so as to be able to survive a poor growing environment by shrinking in size until conditions improve.
They are grown for their beautiful, large, brilliantly coloured flowers and dramatic, dissected leaves which make them ideal for either a mixed or a shrub border. Peony flowers can be divided into four different types: single, semi-double, double and anemone-form. They are usually erect and borne singly and all but the double flowers have a boss of cream or yellow stamens, visible at their centre.
The majority of peonies are herbaceous, with tuberous roots. Tree peonies have woody stems.
This native of China is a sparsely branched, upright deciduous shrub which grows up to 2m (6.5ft) in height and spread and is commonly known as the tree peony. The large bowl-shaped white flowers (15-20cm/6-8in) have petals which resemble paper thin, crushed silk with splashes of maroon paint suffusing into the fibres of the cloth at the base; enhancing the boss of yellow stamens which forms a target for passing bees. The leaves are dark green and blue-green beneath, deeply cut into pointed lobes. Many plants under the name in cultivation are likely to be hybrids and have been given the name Paeonia Gansu Group.
Reginald Farrer was probably the first westerner to see P. rockii when he found this beautiful, rare tree peony while visiting Gansu Province in Western China in 1914. It was believed that he had not collected a specimen until one was identified in 1990, by Haw and Lauener, in the herbarium at the Royal Botanic Garden Edinburgh.
In 1925 Dr Joseph Rock discovered a plant similar to that seen by Farrer growing in the central courtyard of a lamasery in Gansu Province. His expedition collected about 20,000 herbarium specimens for the Arnold Arboretum at Harvard, which distributed seeds of this plant to gardens in Canada, the UK, the USA and Sweden.
Plants derived from a second generation seedling of Rock’s collection sent to Highdown garden from Canada became known as ‘Rock’s Variety’, though it is now felt this name should be restricted to a single clone widely circulated in America.
P. rockii is a very large, deciduous shrub with slightly pendant branches up to 30cm (12in) in circumference and up to 2m (6.5ft) long, after many years.
The leaves are dark green and blue-green beneath, each with nine deeply cut oval leaves. The semi-double flowers are borne in late spring and early summer. They are cup-shaped, white with deep maroon markings at the base of the petals and creamy-yellow stamens.
- Grow in deep, fertile, humus-rich, moist but well-drained soil in full sun or partial shade, sheltered from drying winds.
- Eelworms, swift moth larvae, honey fungus, viruses and peony grey mould can all cause problems.
- Once established, and left undisturbed, it will perform for many years.
- Take semi-ripe cuttings in summer or graft in winter.
- Sow seed in containers outdoors in autumn or early winter. They may take three years to germinate.