Rhododendrons, including the smaller azaleas, are evergreen or deciduous shrubs grown for their spectacular flowers from April to June. Their essential requirement is acid, humus-rich, free-draining soil with pH 4.5–5.5; in limy or heavy soil the leaves turn yellow (chlorosis) and the plant slowly declines. Where the soil is unsuitable, plant in a wide, shallow bed of ericaceous compost or choose varieties grafted onto lime-tolerant INKARHO rootstock. Plant in spring or early autumn with the top of the rootball level with the soil – planting too deep suffocates the fine roots. The root system is shallow and sensitive to drought, so water regularly with soft rainwater and mulch 5–10 cm deep with pine bark. Most varieties prefer light shade and shelter from wind, as strong sun and dry winter wind scorch the leaves. Feed with an acidic rhododendron fertiliser in spring, finishing by July. Gently snap off faded flower trusses so energy goes into next year's buds, and check for vine weevil notches on the leaf edges.