Answer: Endless Summer is unique in that it forms flower buds on both old and new growth. This means it blooms early in the season on stems that grew the year before, then blooms later in the season (and into the fall) from buds that form on the new growth of the season. Depending on whether or not there are any buds on the remaining wood, you may have early flowers next year. You should certainly have flowers later in the season on next year's new growth in any case.
They should regrow relatively quickly due to the now better established root systems. I would expect them to come back bigger and better next summer.
Enjoy your hydrangeas!
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