Answer: Hydrangea serrata is a subspecies of H. macrophylla, and is considered a big leaf hydrangea rather than a Peegee (Hydrangea paniculata). The lace cap flowers are actually sterile flowers, as opposed to fertile, or fully opening blooms.
Prune your hydrangea after bloom, remembering that flowers form on new shoots growing from old wood. Cut the stems back to a node (leaf scar) where you want new flowering wood to develop the following spring.
Since your hydrangea is performing well, I'd say you're providing all the right growing conditions.
Continued good health to your shrub!
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