In addition to providing nuts, walnut trees are drought-resistant and provide shade. You only need to prune them occasionally to remove excess branches and keep the walnut tree healthy. When pruning a walnut tree, keep in mind that the trees can be grown with a central leader (which helps them grow large), or you can keep them smaller by removing the leader. The most common method is to keep the central leader.
Avoid pruning from late winter to early spring, as the sap will seep out a lot during these times. The best time to prune is from half-way through the summer to early fall.
Select the largest, most dominant trunk as a leader. The leader brings the nutrients up from the ground to ensure the other branches grow straight out.
Use lopping shears (for large branches) and pruning shears for smaller branches to remove side branches. Cut along the lines where branches join each other or connect to the trunk. Along the leader trunk, remove the lower branches when the walnut tree is young. Keep larger branches close to the leader, as well as the smaller branches growing from them. Cut out the mediun-sized branches from all areas.
Repeat this method to prune the walnut tree during the first few years of growth until the tree reaches 17 feet.