What's eating my hydrangea?

Hydrangeas face aphids on new shoots, vine weevil grubs in containers, red spider mite in hot dry summers, and scale insects on older stems. Deer and rabbits browse stems and leaves heavily in gardens. Vine weevil is the most dangerous pest for container-grown hydrangeas, destroying roots undetected until the plant suddenly collapses.

Adult weevils leave characteristic notched scallops around leaf margins at night; C-shaped white grubs in the compost eat all roots through autumn and winter, causing sudden wilting and death of container plants. Repot annually to check for grubs; apply Steinernema kraussei nematodes to damp compost in early autumn; pick off adults at night; use vine weevil compost treatments for long-term container protection.

Pale, yellowish colonies on leaf undersides and growing tips; leaves pucker and curl; heavy infestations produce honeydew and sooty mould. Spray with insecticidal soap or neem oil directed at leaf undersides; encourage parasitic wasps and hoverflies with nearby pollen plants; pinch off badly affected shoot tips.

In hot, dry summers, fine pale stippling on leaf surfaces followed by yellowing and bronzing; fine webbing visible on undersides; most common on plants against warm walls. Mist foliage regularly to raise humidity; spray with neem oil or insecticidal soap to leaf undersides; introduce Phytoseiulus persimilis for protected conditions.

Deer strip leaves and bark from stems in autumn and winter, and browse new growth in spring; antler rubbing against woody stems shreds bark and kills branches. Protect individual plants with wire guards around stems; apply deer repellent spray; install deer fencing around the garden perimeter; plant in walled gardens where possible.