Pruning Rhododendrons

When is it ok to prune rhododendrons. What about other shrubs that might not be flowering ones?

Spring flowering shrubs like rhododendron, azaleas, forsythia, bridal wreath spirea and lilac set their flower buds on the previous season’s growth. Wait until after they bloom if you want to control their growth and still have spring blooms. Summer blooming plants like potentilla and summer blooming spirea can be pruned during the dormant season. I like late winter pruning since the plants are able to recover quickly from the pruning as growth begins in spring.