If you want to shape your plant, it’s best to do so immediately following a heavy flowering (likely in June or early July). Light shaping won’t affect blooms for the following year.
If you want to remove spent flowers, you can do so at any time but you’ll need to be mindful about where to cut. For the best success, follow the guidelines below.
L.A. Dreamin’® is a macrophylla type Hydrangea. It will bloom on both new wood (this season’s growth) and old wood (last season’s growth), but the best flowering is on old wood. In more Southern climates, L.A. Dreamin’® Hydrangea is often a better re-bloomer.