Hydrangea macrophylla · Shrub
Slugs and snails: Use physical barriers like copper tape or crushed eggshells, and apply iron phosphate pellets.
Hydrangea scale: Prune out heavily infested branches and treat with horticultural oil during the crawler stage.
Powdery mildew: Improve air circulation, avoid overhead watering, and apply a sulphur-based fungicide if severe.
Leaf spot: Remove affected foliage and avoid wetting leaves when watering to reduce fungal spread.
Vine weevil: Apply systemic insecticide granules to the soil in spring and autumn to control larvae.