Prune a dogwood tree by cutting back diseased, damaged and dead limbs, removing twigs and suckers, and pruning for size and shape. Focus on heavy pruning during the tree's dormant period in the winter and do lighter pruning as required or in early spring before new growth.
First, do the majority of pruning in the late winter or early spring before blooming by cutting the limbs right above the branch collar, which is the base of the branch before it joins with the trunk, but avoid actually cutting into the collar. Cut halfway through a heavy branch from the underside, then finish cutting from the top 3 to 5 inches from the original cut. When cutting smaller limbs, cut above the nearest bud.
Start pruning by removing any dead and damaged wood during the late winter or throughout the year. Be aware of any diseased branches, and remove them immediately whenever you come across them. Sterilize the shears immediately before and after cutting away diseased wood. Snip away any thin and spindly twigs and branches to help improve airflow and minimize disease. Clip off suckers as close to the base of the tree as possible or dig them out. Because dogwood branches can hang, trim back the lowest hanging limbs as well as any rubbing, crossing and awkward limbs.