Hi John,

Thank you for contacting the UNH Extension Yard and Garden Infoline with question about how best to prune the lacecap hydrangeas.  I have included a link to a sheet that should be helpful.

https://extension.unh.edu/blog/2018/10/should-i-prune-my-hydrangeas-now-or-wait-until-spring

This fact sheet notes, "Wait to prune your bigleaf hydrangeas until new growth appears in the spring. Make pruning cuts one quarter inch above the first set of live buds. Hint: stems with live buds will be green on the inside, while dead stems will be brown. Entirely dead stems should be cut flush to the base."

The University of Californian Extension recommends, "Remove dead, diseased, or damaged wood. Remove or shorten crossing branches. Remove up to one-third of the oldest canes, which become less productive over time. Cut them all the way to the ground to spur new growth. On the remaining branches, cut back to a large, healthy bud."