Azaleas are back.
But not as you know them. Let us introduce you a selection of hardy and beautiful varieties and show you how to enjoy an award-winning display, year after year. It’s not all about flowers!
Showy, large-flowering rhododendronazaleas (R. indicum) were once the mainstay of spring gardens. But their susceptibility to pests and diseases,coupled with their inability to recover from the attacks, led to their ultimate abandonment. One species of azalea, the Kurume (Rhododendron obtusum), is resistant to the dreaded ‘Petal Blight’ fungus. The name refers to a group of evergreen azalea cultivars bred in Kurume, Fukuoka Japan. Flowers are small to medium sized, brightly coloured, and numerous. Foliage is small and responsive to clipping, as in Japan, into neat, rounded shapes. I have always loved the ‘Famous 50’ selection of azaleas, collected by Englishman E.H. Wilsonon his numerous plant-collecting expeditions to China, Korea and Japan from 1899 to 1919.
Azaleas are not the ‘set and forget’ plants they were once considered. Things changed with the arrival of the ‘Two Spotted Mite’, petal blight fungus, and the market release of susceptible varieties of azaleas. Having travelled to Japan annually for the last 40 years, I’ve observed a very different approachto growing azaleas. With the right care, goodhygiene, and good pruning technique, you will be rewarded with good-looking, compact shrubs with fabulous flowers, and lush, evergreen foliage all year round.
Azaleas grow best in warm and cool temperate areas.
Select a spot with morning sun, andprotection from fierce afternoon sunshine.
Soil should be well-drained, and organically enriched with aged cow manure, compost,and leaf mould.
If your soil is heavy, mostly clay, you can improve drainage by mixing in coarse rivers and or course grit.
Raised garden beds work well for azaleas because of the inherent good drainage.
Azaleas grow happily in shallow, broad pots. Choose an azalea/camellia potting mix for best results. Resist the temptation to use a saucer which will prevent your potted azalea from freely draining. Azaleas are surface rooting, so avoid deep pots.
Acid-loving plants like rhododendron andazalea, and camellia, can be fertilised with organically-based Kahoona (Neutrog).
Sprinkle the pellets over the root system, topre-moistened soil, every 8-10 weeks afterspring flowers to end of autumn. Mulch to 4cm, no thicker, during summer to keep roots cool and moist. Use cow manure, ‘WhoFlungDung’ or your own homemade compost.
I have copied Japanese gardeners, who get the best results from regular, but specific pruning. Once flowering has finished in October, lightly trim to remove all new spring growth, back to your predetermined shape. Lightly trim new shoots that appear in early summer (they make for great cutting material at this time). One more trim is needed in mid-January to remove new growth. You will be delighted with the result of this pruning! Your azaleas will look compact, full of fabulous foliage with masses of short stems. Pruning must now stop as tiny flower buds will be forming in the axils of the leaves. Pest control programme This should start after the first spring prune. Red spider mite, also known as the ‘Two Spotted Mite’ feeds on the sap from the underside of leaves and cause the foliage to become discoloured and unsightly. Mites favour hot, dry conditions, so placing a sprinkler under your azaleas, for a few minutes in hot weather, can act as a deterrent. There are a few options to control this mite: Yates Nature’s Way Vegie & Herb Spray (Natrasoap), eco-neem and eco-oil. All safe for use around bees.
Image: Graham's pruner of choice is a cordless hedge trimmer.
Root rot (Phytophthora) in old plants can cause die-back and leaf drop. Good drainage is essential. Overwatering should be avoided as wet conditions favour this pathogen. Leaf droop is an early sign of root-rot attack. Immediate use of a phosacid fungicide such as Amgrow’s Rot Guard or Yates Anti Rot can help. Petal blight fungus attacks larger-flowering rhododendron azaleas (R. indicum and hybrids). The flower becomes limp, slimy, then brown. Misty, rainy weather and overhead watering encourages this fungus. Note that Kurume azaleas are resistant. Remove infected flowers and any spore-laden litter on the ground, then spray with Mancozeb fungicide every 10 days from first sign of colour in flower buds.
Image: Close up of the damage caused by the two spotted mite.