Red oaks are a Northeastern hardwood tree prized for their lumber, while producing acorns that are a prized nut for many species of wildlife. There are many reasons to consider trimming a red oak, which may include removing diseased branches, to restrict its growth from certain areas, or even as a way to train the tree to grow a certain way. In any one of these cases, it may be in the best interest--of both the tree and the landscape around it--to trim the tree.
Start by trimming all dead and diseased branches and limbs. Higher branches can be pruned with an extending pole saw, while lower branches can either be trimmed with power tools such as a chainsaw, or it they are small enough in diameter, they can be cut with a lopping tool or hand pruning shears.
Step back after removing the dead branches by cutting with the appropriate trimming tool, and see where you want your oak tree to go. Remove canopies that interfere with power lines using an extending pole saw that will reach higher up into the branches. Remove lateral branches with either a hand saw or chainsaw, if they are within reach; or a pole saw if they are out of reach. Remove these branches and shape the tree on a side where you want less foliage to be present. Smaller diameter branches within reach can be lopped off with hand shears.
Trim all branches that are more than 1 1/2 inches thick by using the three-step method. Measure 6 to 12 inches from the trunk with you tape measure and saw an undercut about 1/3 of the way through. Next, measure out 3 inches from the undercut and saw off the entire branch. The final step entails cutting off the rest of the stub where the branch meets the trunk on a roughly 45-degree angle.
Trim red oak trees only between the months of November through March to avoid the spread of oak wilt disease.
In all cases, trimming should only be done from the ground with hand-held tools for the job. If high canopies or broken branches need to be trimmed far up into the tree, a professional service must be called in to eliminate and chance of injury to you or from falling branches.