Getting the best from rhododendrons and azaleas

rhododendrons at Temple Newsam Park, Leeds. By Catherine Ruane
rhododendrons at Temple Newsam Park, Leeds. By Catherine Ruane

Rhododendrons and azaleas are two of the most beautiful sights in gardens when they are in full flower although not many people have the option to choose and plant these beauties unless their garden is big enough.

Quite often a garden may face the wrong direction, suffer from strong prevailing winds or have an alkaline soil which can make life difficult for a keen horticulturalist.

Les Foden.

Les Foden.

A few rhododendrons can be grown in almost any aspect, with the exception of areas immediately next to buildings which as a result receive no sun at any time of day.

In a position such as this foliage tends to lack colour and is rather drawn. Consequently the plants seldom, if ever, produce flowers.

An eastern aspect is in many ways the most difficult to manage. The problems arise in spring when flower buds start to open while frosts are still prevalent.

The sudden rise in temperature as the early morning suns trikes the petals causes much more damage than if the buds were allowed to thaw out slowly.

The localities in which the rhododendrons are to be found growing in the wild are excellent indications of the conditions which they require in cultivation.

The alpine species, such as RR. ferrugineum and hirsutum, with their small, tough, leathery leaves, grow well in full sun, while the large-leaved species require a degree of protection from cold, drying winds and strong sun.

In small gardens it is impossible to plant large trees for shelter and it is therefore advisable to grow the varieties which are considered extremely hardy.

When experience has been gained the more tender species can be tried using shelter provided by larger, established shrubs or artificial windbreaks.

Windbreaks are invaluable, especially in coastal areas where damage from salt laden wind can prove fatal to many plants.

Acid soil is essential with a pH of 4.5-5.5. In limey soil the leaves turn yellow – water with Sequestrene if this happens.

Azaleas are usually termed as a distinct group, usually daintier than rhododendrons but not always as there are 10 foot azaleas and 12 inch rhododendrons.

When pruning break off dead flowers with finger and thumb and make sure that the buds at the base aren’t damaged. If stems have become leggy and bare cut back hard in April.