Top 10 Rules for Spring Gardening: #10 Hydrangeas are the exception to...
Hydrangeas are the exception to the pruning rules for summer-flowering shrubs. Mophead hydrangeas— and others that flower in summer— need to be pruned in fall. Fall-blooming hydrangeas such as H. paniculata are pruned in late winter or early spring. Source: HGTV.com Sign in to see full entry.