Caring for Rhododendron

Rhododendrons have moderate water needs but dislike both drought and waterlogging. Water regularly during dry spells from spring through autumn, especially in the first two years after planting. Aim to keep the root zone consistently moist but never saturated. In hot, dry summers, water deeply once or twice a week rather than little and often. Reduce watering in winter, but check evergreen foliage during prolonged dry spells—desiccation is a common cause of winter damage. Feed in March and again in April with a slow-release ericaceous fertiliser formulated for acid-loving plants. Scatter granules evenly around the base, avoiding direct contact with stems, and water in well. Never use general-purpose or high-nitrogen feeds, which can cause lush growth prone to frost damage and may raise soil pH over time. Refresh the mulch layer each spring with acidic organic matter to maintain soil acidity, suppress weeds and conserve moisture. Rhododendrons are evergreen and fully hardy in zones 5a–8b, so they need no special winter protection in temperate Europe, though young plants benefit from shelter from cold, drying winds. Watch for vine weevil, whose larvae chew roots and can kill plants; treat with biological nematodes in late summer. Rhododendron leaf hopper causes unsightly brown spots and spreads bud blast, a fungal disease that blackens flower buds—remove affected buds promptly and control hoppers with insecticide in late summer. Powdery mildew and rust occasionally affect foliage in humid conditions; improve air circulation and avoid overhead watering. Yellowing leaves (chlorosis) indicate alkaline soil or hard tap water—remedy with sequestered iron and rainwater where possible.