Site and soil
Plant in an area of semi-shade - the dappled shade beneath open-branched trees is a favourite location. Azaleas will grow in more open situations, but they prefer morning sun, with protection from hot afternoon sun in summer. They like a mildly acidic, organically enriched soil (pH 5-6), so avoid applying lime or fresh manures. Before planting, feed soil with compost and aged manure to improve moisture retention. Don't plant azaleas in cement pots or near new brickwork as the lime from the pot or mortar can leach into the soil, making it alkaline.
Azaleas are surface-rooting plants, so they don't need very deep soil to thrive - about 30-40cm is adequate. It is important with new plants to tease the roots out gently before planting, to help them establish well in the garden. After positioning in the hole, backfill, mulch and water well with a seaweed solution.
Azaleas can be pruned to remove unwanted growth and diseased or damaged growth, and to shape them after flowering. In fact, they respond very well to pruning, so they're perfect for growing as hedges or trimming into standards. If you want tall-growing azaleas to stay compact, prune them back by about one-third after flowering.
Feed azaleas every spring, after their flowers have finished, with either a pelletised organic plant food, or a slow-release granular fertiliser. Follow this with a layer of organic mulch to reduce soil evaporation and so reduce their water requirements. As with all garden shrubs, a second fertilising during autumn is recommended to encourage strong, healthy, well-nourished plants.
- It’s especially important to choose the right location to plant. They thrive in slightly acidic soil with a pH between 5.5–6.0 and most prefer some filtered shade overhear, under trees is ideal.
- Azaleas have a shallow root system and require loose, well-aerated soil with plenty of humus to retain moisture.