Answer: There's really no rhyme or reason for the non-blooming. I suspect you are growing Hydrangea macrophylla (big leaf) and if so, they flower on new growth of the season. To maximize the flowering you should prune your plants back in the spring. This will encourage twice as many flowering stems than if you don't prune. Go easy on the ferilizer - too much nitrogen can promote lots of lush, green growth but sometimes at the expense of flowering. Wish I had more to share with you.
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