Growing azaleas


While azaleas are nowhere near as popular as they were some years ago, they’re still hard to beat when it comes to producing a mass of garden colour in winter and spring. Azaleas vary in size from small, rather delicate shrubs that are happiest in pots, to the large, hardy Indica varieties that seem able to survive all the climatic challenges that are thrown at them. The latter group includes salmon-pink ‘Splendens’ that can reach up to more than two metres tall.

In cold climates, deciduous azaleas that bloom in shades of orange and yellow can produce a spectacular spring display.

General care

Most azaleas are at their happiest when grown in semi-shade or morning sun. They’re woodland plants that have evolved to grow in the generations of leaf litter that have built up under forest trees. This type of leaf-mulch-derived soil is naturally acidic, which makes azaleas difficult to grow in soils that are tending towards the alkaline. In order to achieve success with azaleas in alkaline soils, mix some moistened peat moss and milled cow manure into the garden bed before planting.

Always maintain a layer of organic mulch (e.g. a 10 centimetre thickness of old leaves) over the shallow roots. This insulates the roots and helps protect them from drying out. Feed a couple of times a year with a suitable fertiliser such as Thrive Granular Azalea, Camellia & Rhododendron Food. Acticote or Nutricote are suitable for feeding plants in pots.


The Japanese have taken pruning of azaleas to new heights by clipping the plants into neat buns that rarely allow stray shoots to escape. Pruning isn’t always necessary but it will help keep the plants in good shape. Prune immediately after flowering finishes. With some varieties (e.g. Red Wing – pictured) blooming continues for months so it’s important to be patient. After flowering, you can cut back as hard as you like because azaleas have the amazing ability to produce shoots from almost anywhere on the stem. Tall, wayward shoots can be shortened at other times of year but remember, general cutting back close to flowering time will reduce the display.

Pests and diseases

One of the reasons for the decrease in azalea popularity is that the plants are affected by a number of pests. Fortunately, some recent product introductions have made their control much simpler. Sap-sucking thrips attack the leaves during the growing season. Effective control is now much easier with the help of Nature’s Way Citrus, Vegie & Ornamental but it’s important to begin spraying early in the season before the pests appear. Once the leaves are damaged they are spoilt for good. Leaf roller caterpillars can be controlled with the help of Yates Success. Lichen on old azaleas worries some gardeners, while others love it. Lichen on the stems and branches can be controlled by painting with Lime Sulfur.


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