Hydrangea 'Annabelle' Frost Damage vs. Fungus

Newly planted 'Annabelle' hydrangeas in heavy clay amended with peat, manure, and sand developed black spots and mushy new growth after heavy rain. The symptoms appeared following hard frosts.

Theresa Schrum advises that frost-damaged hydrangea foliage turns to black mush exactly as described. Wait and watch: if fresh growth stays healthy once frosts cease, it was cold injury. If new leaves also blacken and collapse without further freezes, a fungal issue is likely.