Saturday, July 2, 2016
How to Grow Rhododendrons and Azaleas
Rhododendrons and Azaleas prefer locations where they receive semi or dappled shade. They will grow in open spaces, but prefer morning sun with protection from the hot afternoon sun.
Rhododendrons and Azaleas prefer a slightly acidic soil (pH 3-6) that is well-draining and high in organic matter.
Prior to planting, feed the soil with compost and aged manure in order to condition the soil and improve moisture retention.
* Do NOT plant Rhododendrons and Azaleas in concrete or brick pots or containers as the lime in the mortar can leach into the soil, making it alkaline.
Rhododendrons and Azaleas are surface-rooting plants, so therefore do not need deep soil in order to thrive. 30 to 40 centimetres is adequate.
With new plants it is important to gently tease out the roots prior to planting to help them establish themselves well.
After positioning the plant in the prepared hole, backfill, mulch and water well with a seaweed solution.
Rhododendrons and Azaleas can be pruned once they have finished blooming. They can be fed with either a pellet-form of organic plant food, or in slow-release granular form.
Follow this with a fresh layer of organic mulch to reduce soil evaporation.
Fertilize again in Autumn to encourage strong, healthy plants.
Rhododendrons and Azaleas can be pruned to remove diseased and/or damaged branches or foliage, and to shape them after flowering.
Azaleas respond well to pruning and make perfect specimens for growing as hedges or trimmed into standards.
Rhododendrons however, should only be pruned very lightly and only if needed.
Pests and Diseases
Rhododendrons and Azaleas are both prone to pests and diseases.
Petal blight is a fungal disease that turns the flowers brown. The easiest solution is to pick off the affected flowers. Petal blight can also be combated with the use of a commercial or organic fungicide.
Azaleas can be prone to ‘lace bug’ infestations, which causes brown spots under the leaves. A symptom to look out for is leaves suddenly turning a silver colour. An organic solution is ‘glue spray’ and ‘oil spray’ amongst others. Commercially, Pyrethrum spray is appropriate to use to combat Azalea lace bug.
Tips for growing Rhododendrons and Azaleas
When planting your Azaleas and Rhododendrons, choose a forecast period of several cool, overcast days. Plant either early or late in the day, avoiding the midday sun. Do not plant in hot or windy weather as moisture loss from the leaves is best avoided.