The best time to prune Azaleas is right after they're done blooming. If they finished blooming within the last four weeks, it's not too late. Pruning your dogwood (Cornus species) depends if it's a tree or shrub. Generally, dogwood trees don't require much pruning, but if you must, prune them right after flowering. Dogwood shrubs should be pruned in late winter or early spring. You can also thin them in summer without doing any harm.