Troubleshooting
Nikko Blue Bigleaf Hydrangea problems — and how to fix them
Nikko Blue Bigleaf Hydrangea (Hydrangea macrophylla 'Nikko Blue') is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Wrong flower colour / fading
Blue requires soil pH 4.5–5.5 with available aluminium; pink occurs in alkaline soils. Use rainwater and ericaceous compost to maintain blue. Fading in strong sun is prevented by afternoon shade.
No flowers (pruned at wrong time)
'Nikko Blue' flowers on previous year's wood; prune only immediately after flowering (typically August–September in the UK). Autumn or spring pruning removes next year's buds.
Powdery mildew
White coating in warm, dry, still conditions; improve airflow and water at soil level to avoid wetting leaves.
Wilting in heat
Normal afternoon wilting in hot sun; if still wilted in the morning, the plant needs more water or less sun.
Frost damage to buds
Late frosts kill emerging buds, especially in exposed positions; protect with fleece and site in a sheltered spot.
Prevent nikko blue bigleaf hydrangea problems before they start
Most nikko blue bigleaf hydrangea issues are care-mismatch, not bad luck. Dial in the basics:
Nikko Blue Bigleaf Hydrangea problems — FAQ
Why is my nikko blue bigleaf hydrangea wrong flower colour / fading?
Blue requires soil pH 4.5–5.5 with available aluminium; pink occurs in alkaline soils. Use rainwater and ericaceous compost to maintain blue. Fading in strong sun is prevented by afternoon shade.
Why is my nikko blue bigleaf hydrangea no flowers (pruned at wrong time)?
'Nikko Blue' flowers on previous year's wood; prune only immediately after flowering (typically August–September in the UK). Autumn or spring pruning removes next year's buds.
Why is my nikko blue bigleaf hydrangea powdery mildew?
White coating in warm, dry, still conditions; improve airflow and water at soil level to avoid wetting leaves.
Why is my nikko blue bigleaf hydrangea wilting in heat?
Normal afternoon wilting in hot sun; if still wilted in the morning, the plant needs more water or less sun.
Why is my nikko blue bigleaf hydrangea frost damage to buds?
Late frosts kill emerging buds, especially in exposed positions; protect with fleece and site in a sheltered spot.