Why does your Hydrangea macrophylla Magical Amethyst have white cottony spots? Diagnose the cause and fix it with our step-by-step guide.
These sap-sucking insects produce a white, waxy, cottony secretion to protect themselves while feeding on the hydrangea's stems and leaf undersides. They can cause leaves to yellow and eventually drop if the infestation becomes heavy.
While typically appearing as a dusty film on the surface of leaves rather than distinct 'spots,' severe infections can look like white patches. This fungal disease thrives in the humid, stagnant air common around dense Hydrangea macrophylla foliage.
In high humidity, Botrytis can cause soft, decaying spots on petals and leaves that may develop a fuzzy, greyish-white appearance. This is particularly common during the blooming phase of 'Magical Amethyst' if moisture lingers on the flowers.
Your plant might also be experiencing one of these issues:
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