GARDEN ADVICE

How to Grow Rhododendrons and Azaleas

The Rhododendron family is a very large plant family. It includes both Rhododendrons and Azaleas. In the first part of the 20th Century many species were brought to these shores from China and the Himalayas and plantsmen put a great deal of energy into making plant crosses to create the hybrids that we know today.

Most of these hybrid Rhododendrons tend to be evergreen and form attractive bushes which are slow growing and can range in size from 50cm to 2m in height. They have dark green leathery long leaves and large flowers in an amazing choice of colours from Geisha Orange to red Van Dyke.

Azaleas on the other hand tend to be more dainty with smaller leaves and flowers in clusters. Some Azaleas are evergreen whilst others are deciduous. Mrs. Carrington is a good white example and Nova Zembla is purple.

Both Rhododendrons and Azaleas require a lime free soil with a good organic matter content. Most thrive in dappled shade but do not enjoy cold windy situations.

These plants are surface rooting and therefore should only be planted in a shallow hole so that the root ball is just covered with soil. Many of the smaller varieties can be grown in containers provided that ericaceous compost is used. Indeed this is the only option if you garden on alkaline soil. Generally the soils in this area are suitable for Rhododendrons and Azaleas.

The only pruning that is needed with these plants is to deadhead the flowers. Another advantage is that, due to their shallow roots, they can be moved with relative impunity no matter how well established they are. However, this should only be done between October and March and not while the plants are in full growth. Whilst Azaleas and Rhododendrons are good no-nonsense easy to grow plants requiring very little attention, they will benefit from an application of fertilizer for acid loving plants in the spring and a good mulch with well rotted compost or leaf mould.

Vine weevil can be a problem particularly with container grown plants. There is also a nasty little bug called the Rhododendron leaf hopper which spreads a fungus which causes bud blast. Symptoms are the buds failing to open and turning brown and dry instead. The way to control this pest is to remove affected buds and destroy them before the leaf hopper becomes widespread in the middle of summer. However, these bugs really are a minor irritation and should not detract from growing a plant which gives so much pleasure over very many years.