The Zimbabwean Gardener Issue 6 Spring 2013 | Page 16

Plant profile Azaleas By Barbara Burrell Azaleas, which are part of the Rhododendron genus, flower mainly from April to September. There are hundreds of varieties, and many can be found in nurseries around Zimbabwe. There are lots of benefits to growing them, such as: • They bloom when they are very young • They are reasonably free of pests and diseases • The flowers last well in a vase • They are ideal in containers • Not much care is needed • They give a spectacular show of colour and variety. Position Azaleas are woodland plants so they do best in dappled shade, or morning sun and afternoon shade. Therefore, an east or south facing wall would be satisfactory. Soil The soil must be acid with a pH between 4.5 and 6. Beware of flowerbeds, which are close to newly built walls, as these can contain builders’ rubble, mortar and lime all of which are alkaline, including Municipal water, wood ash and tobacco scrap. Make sure you plant azaleas next to acid loving plants or plant them in a pot and then bury it – this helps you to control the azaleas environment. If the soil is alkaline, you can make it acid with aluminium sulphate, which is available from swimming pool suppliers; use half a cup to a square metre. Sprinkle on the surface and lightly fork it in and water it in well. Another option is to add a tablespoon of vinegar to a can of water each time you water during the first month. Reduce to a tablespoon once a month. 16 Azaleas, Rhododendron indicum, are evergreen, frost hardy and uncomplicated plants to grow. Give them what they want and you will be amply awarded. Planting When planting, make sure you plant azaleas in well-drained soil; half should be compost or a leaf mould and the rest sand and topsoil. Remember to add superphosphate when planting. Mulching is essential; use pine needles or any fine textured leaf mulch such as grass cuttings. Do not dig this in as feeding roots are very close to the surface. If planting your azaleas in the ground, dig a hole 1m wide by 70cm deep. Put stones in the bottom, add your soil mixture, and water twice a week. Azaleas do very well in pots, as they are shallow rooted and the soil can be well regulated. If asbestos pots are used, soak them well and line with plastic or paint with bitumen. Make sure the pots have holes in them to ensure proper drainage, place stones in the bottom to help drainage and then fill with your soil mixture. Feeding & watering Spray with a good foliar feed every two weeks and feed with Fruitfert (Compound J) twice a year. They require a lot of water, especially during the summer months from January to March. This is when the flower buds are formed and if the plants are not kept moist at this time of the year, you will get bud drop and brown budding when the plant is expected to flower. Mulching the plants helps to retain the moisture in the soil and with these varieties, it is essential. Maintenance It is a good idea to deadhead azaleas and pinch-prune them as they finish flowering. Do not prune them unless they become leggy or there is a rogue branch. To encourage them to bush out, pinch the smaller growth tips when they are small and this will encourage side shoots. They can be cut down to get growth that is more vigorous. Azaleas are easy to transplant as they are shallow rooted. And they can be turned into standards by training the main shoot. Propagation This is done from tip cuttings; taking a cutting from the tip and removing the lower leaves. Then dip into a growth hormone such as Seradix, and finally plant into sand. Problems If the leaves turn brown around the edges, suspect drought, over fertilising, or digging too close to the plant. If leaves turn yellow, suspect that the soil is not acid enough. To fix this, use one of the following remedies: • Dig in half a cup of aluminium sulphate to a square metre of soil. • Dig in 50g powdered sulphur to a square metre of soil. • Spray with 2 tablespoons of aluminium sulphate to 10 litres of water. • As a tonic, give 2 tablespoons of magnesium sulphate (Epsom salts) to 5 litres of water. If leaves turn yellow and brown at edges and begin to fall off, suspect heavy soil and poor drainage (waterlogged soil). The best thing to do is replant your azalea. Azaleas are very rarely attacked by pests. Petal blight and black spot can be treated with a fungicide.