Answer: The most common reason for non-blooming in blue hydrangeas is winter damage. These bloom on old wood that grew the previous year, so if winter kills back the plant each year, there will be few or no blooms. For the same reason, pruning in spring can limit or eliminate blooming. Many varieties are root hardy in your zone but not stem hardy, so I suspect hardiness is the problem rather than siting or care. Wish I had better news for you!
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