When should I prune summer-flowering deciduous shrubs?

FAQ
Question: 

When should I prune summer-flowering deciduous shrubs?

Answer: 

Summer-flowering shrubs, such as potentilla, Japanese spirea, and panicle hydrangea, bloom in summer on the current year’s growth.  Prune summer-flowering shrubs in late winter or early spring.  The pruned shrubs will bloom in summer on the current season’s growth.