Gardens

RHS Garden Wisley

Plant of the Month: May

    

Rhododendron ‘Dopey’ AGM  @ Wisley

A magnificent collection of rhododendrons can be found planted on Battleston Hill. Flowering alongside camellias and magnolias through spring and early summer the best time to visit is May. Up opposite the Temple is a collection of dwarf Yakushimanum hybrid rhododendrons known as the Seven Dwarfs (although ‘Happy’ is actually named ‘Hoppy’). ‘Dopey and ‘Bashful’ both have AGMs and all are available in the Plant Centre, subject to availability.

Rhododendron

The Rhododendron genus comprises between 700 and 800 species of trees and shrubs. Its range is scattered in northern temperate regions and extends into the southern hemisphere in south east Asia and it just reaches Australia. However there are two distinct areas of concentration, south west China (Yunnan, Sichuan, Xizang) with adjacent Burma and India, and Papua New Guinea.

Rhododendron is one of the most diverse genera in the plant kingdom, the majority are evergreen shrubs, many with ornamental foliage and attractive bark, and nearly all with showy attractive flowers. Nearly the whole spectrum of colours is represented in the flowers, only the true blues are missing. Several are sweetly scented, the majority of these are white-flowered.

The hardiness of rhododendrons is also very variable, from fully hardy to frost-tender, but unfortunately the flowers are susceptible to frost damage, especially when fully expanded

Rhododendron ‘Dopey’ AGM

This is a R. yakushimanum hybrid, with a small, compact habit, suitable for small gardens. It has an upright, compact habit and is evergreen with medium sized leaves, but with no indumentum (hair). In late spring it bears neat, full trusses of long-lasting, bell-shaped, glossy red flowers 5-7cm (2-3in) long, with dark brown spots inside, paler towards the margins. 

AGM

The RHS Rhododendron and Camellia Committee awarded Rhododendron ‘Dopey’ an Award of Garden Merit and described it as: Bushy, small, hardy hybrid with dull green leaves and rounded trusses of deep red flowers which fade slightly at the edges

Cultivation

Nearly all rhododendrons demand a humus-rich acid soil, ideally a pH of 4.5 to 5.5, and shallow planting is essential as rhododendrons are surface-rooting.

Most of the large-leaved species and hybrids require a location in dappled shade where there is all year round moisture as they should never dry out during the spring and summer.

Rhododendrons do not require regular pruning and most are best left to grow naturally, old plants though can be severely pruned to rejuvenate them.

To encourage better growth and to promote flowering spent flowers should be removed, this is important in newly planted rhododendrons to help them establish.

Rhododendrons are susceptible to many and varied pests and diseases including vine weevil, leafhoppers, scale insects, bud blast, honey fungus and lime-induced chlorosis if the soil is not sufficiently acid.

Propagation

Named rhododendrons can be propagated by semi-ripe cuttings in late summer, by layering in autumn or grafting in late winter or summer.

If you want to find out more about rhododendrons you can visit the RHS Rhododendron, Camellia and Magnolia Group website