Answer: Based on your description I am guessing you have the bigleaf type or Hydrangea macrophylla. These bloom from buds formed on wood that grew the previous year. If the wood died back over the winter, or was trimmed off, or if a late frost damaged the buds, then there will be fewer blooms -- or no blooms -- this year. Unfortunately, the next opportunity for blooming is next summer. If you plan to overwinter them, be very careful to protect them (both tops and roots) from wind and harsh cold; this is especially important since they are in pots.
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