Rhododendrons an enormous genus and there are thousands of cultivars. They form either shrubs or trees, varying in height from just a few centimetres up to 10m (30ft) and more.
Many are too large for a small garden, both in height and spread, but this still leaves plenty to choose from. The main attraction is the flowers, but many also have very attractive foliage.
The general shape of the flowers is bell shaped, sometimes narrowing to a more tubular shape and at other flaring out to a trumpet shape or even wider to a saucer shape. There is a very wide range of colours and colour combinations. Some are fragrant.
Most are evergreen and the leaves are oval in shape and quite leathery in texture. The reverses of the leaves often have an attractive, white, brown or rust colour fur.
Azaleas form one of the many groups in which into which the rhododendrons are broken. They can be either evergreen or deciduous. These tend to have small flowers which generally smother the shrub. Many are fragrant.
Rhododendrons must have an acid soil, or at least neutral. In chalky or lime areas the only practical way to grow them is containers filled with imported soil or compost and water them with rain water that has not touched the chalky soil. Rhododendrons generally need little pruning, although they can be cut back if they get too large.