Rhododendrons are grown for their spectacular flowers, usually borne in spring. Some also have young leaves and stems covered in a striking dense woolly covering (indumentum) and some - the deciduous rhododendrons or azaleas - have good autumn colour.
Common name RhododendronBotanical name RhododendronGroup Evergreen and deciduous trees and shrubsFlowering time Mainly springPlanting time Autumn or springHeight and spread VariableAspect Generally light dappled shadeHardiness Mostly fully hardyDifficulty Moderate
Choose a site with dappled shade in sheltered conditions. Avoid deep shade beneath other trees. Most rhododendrons will tolerate a more open site if sheltered from cold, dry winds. Dwarf alpine species will tolerate full sun provided the soil does not dry out. Avoid frost pockets and sites exposed to early morning sun.
In spring, an application of ericaceous fertiliser, controlled release fertiliser pellets, or ‘Vitax Q4’ at a rate of 70gms per m2 (2oz per sq yd) in cool, moist conditions is beneficial.
Rhododendrons don’t require much pruning other than the removal of dead wood and deadheading of spent flowers if practical.
Only species rhododendrons come true from seed. Named cultivars must be propagated from cuttings, grafting or layering. Rhododendron cuttings are taken with a heel and wounded to encourage rooting. See our profiles on layering and semi-ripe cuttings for further information.
The following should be available in plant centres and nurseries:
Rhododendron ‘Cynthia’ AGM: Grows to a height and spread of 6m (20ft) with trusses of rose-pink flowers in late spring.Rhododendron dauricum ‘Midwinter’ AGM: Very hardy, deciduous or semi-evergreen variety with a height and spread of 1.5m (5ft) and rose-purple flowers in early spring. Rhododendron ‘Dopey’ AGM: Evergreen variety with a height and spread of 2m (6ft) and long-lasting red flowers in late spring.Rhododendron macabeanum AGM: Evergreen tree rhododendron with huge trusses of creamy to deep yellow flowers in mid-spring and large leaves to 30cm (12in) long; eventual height of 15m (50ft) and spread of 6m (20ft). Rhododendron luteum AGM: Deciduous type for full sun with a height and spread of 4m (12ft) and strongly scented yellow flowers in late spring. Rhododendron yakushimanum ‘Koichiro Wada’ AGM: Dome-shaped rhododendron to 2m (6ft) across and high, with rose-pink buds opening to pale pink flowers in late spring.
RHS Plant selectorFind a stockist with Plant FinderAGM recommended varietiesRHS Plant Bulletins
CamelliaPlant register: rhododendronsRhododendron diseasesRhododendron leafhopper and bud blastTrees and shrubs: plantingTrees and shrubs: establishment problemsRHS Rhododendron, Camellia and Magnolia GroupRHS Publications: Rhododendron, Camellia and Magnolia YearbookRHS Publications: Rhododendron yakushimanum bulletin
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delboy on 05/07/2014
How can I treat my Rhododendron that has
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