• AGM plants

    AGM plants have been through a rigorous trial and assessment programme. They are:

    • Excellent for ordinary use in appropriate conditions
    • Available to buy
    • Of good constitution
    • Essentially stable in form & colour
    • Reasonably resistant to pests & diseases

Paeonia rockii (S)

Rock's tree peony

Rock's tree peony

© RHS

  • Other common names Rock's tree peony

  • Family Paeoniaceae

  • Genus Paeonia may be herbaceous perennials or deciduous sub-shrubs with large, divided leaves and showy large bowl-shaped flowers, usually in early summer

  • Horticultural Group Shrubby peonies are sparsely branched deciduous shrubs leaves divided into several finger-like lobes, and bowl-shaped flowers in late spring or early summer

  • Details P. rockii is a lax deciduous shrub to 2m tall and wide, with dark green, divided foliage and semi-double white flowers 25cm across in late spring and early summer, each petal with a bold deep maroon blotch at the base

  • Plant range China

Characteristics

  • Foliage Deciduous

  • Habit Bushy

  • Toxicity If ingested all parts can cause mild stomach upset

  • Hardiness

    Hardiness ratings

    All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

    • H1a - Under glass all year (>15C)
    • H1b - Can be grown outside in the summer (10 - 15)
    • H1c - Can be grown outside in the summer (5 - 10)
    • H2 - Tolerant of low temperatures, but not surviving being frozen (1 to 5)
    • H3 - Hardy in coastal and relatively mild parts of the UK (-5 to 1)
    • H4 - Hardy through most of the UK (-10 to -5)
    • H5 - Hardy in most places throughout the UK even in severe winters (-15 to -10)
    • H6 - Hardy in all of UK and northern Europe (-20 to -15)
    • H7 - Hardy in the severest European continental climates (< -20)

    H6

Colour

Sunlight

  • Full Sun

  • Partial Shade

  • Aspect South-facing or West-facing

  • Exposure Sheltered

Soil

  • Loam

    Loam

  • Clay

    Clay

  • Sand

    Sand

  • MoistureWell-drained

  • SoilLoam, Clay, Sand

  • pHAcid, Alkaline, Neutral

Size

  • Ultimate height 1.5-2.5 metres

  • Ultimate spread 1.5-2.5 metres

  • Time to ultimate height 5-10 years

How to grow

Cultivation Best grown in neutral, humus rich soils, but slightly acid or slightly alkaline soils are tolerated. Good drainage is essential. Ideally, plant in a sunny position. Can be grown in light shade, but the plants may become straggly. Fully hardy, but young foliage and flower can be damaged by late frost. Further tree peony cultivation advice

Propagation Propagate by seed, seeds are doubly dormant needing two winters to germinate. There is a good chance that the young plants will be true to type or similar. Propagate by grafting, from semi-ripe cutting or try layering

Suggested planting locations and garden types Flower borders and beds City & Courtyard Gardens Cottage & Informal Garden

How to care

Pruning pruning group 1

Pests The foliage can be damaged by various caterpillar pests. Roots can be eaten by swift moth caterpillars

Diseases Can be affected by a virus - peony ringspot virus, peony wilt, verticillium wilt and honey fungus

Advertise here

Did you find the information you were looking for?

RHS members can get exclusive individual advice from the RHS Gardening Advice team.

Join the RHS now

Get involved

We're a UK charity established to share the best in gardening. We want to enrich everyone's life through plants, and make the UK a greener and more beautiful place.