Shrubs are often pruned to remove dead wood and to keep them from overgrowing their boundaries. Different shrubs have different growth habits, so care must be taken when pruning shrubs to cut the limbs in a way that compliments the growth of the shrub without it looking misshapen or unnatural after the pruning is finished. It is always best to prune shrubs once or twice year because it keeps the plants from getting stressed from a severe pruning. However, if you need to trim very tall shrubs that have grown out of control, follow the correct procedure to recreate attractive landscape specimens.
Decide how tall you would like the shrubs to be after they are pruned in late winter. A very tall shrub is often a collection of branches in different stages of vigor, often with some dead. Saw or prune out all the dead branches by cutting them back to the point where they join a larger branch or to the ground. Wear garden gloves and safety glasses to prevent injury to eyes and hands.
Locate the tallest branches that need to be removed. Remove one tall branch at a time by cutting the branch back to its point of origin where it joins a main limb. If the branch is growing from the ground, cut the branch to the ground. Do not cut all the branches off to one level like a hedge. This will create an unattractive shrub with few leaves and large limbs with numerous small branches when it begins to regrow in the spring.
Continue to cut the limbs that are too tall back to a main branch or to the ground until the desired height of the shrubs is reached. Once the desired height is reached you may shear the top to one level as you would a hedge or leave the shrub in a natural shape. If you are shearing the sides and top to form a dense hedge, trim the sides so the bottom is slightly wider than the top. This allows sunlight to reach the bottom of the shrub and prevents the lower portions from becoming woody and unattractive.