Most foresters and hardwood forest landowners in the Central United States believe you must prune black walnut trees from late winter to early spring (February-April). At this point, you can begin shaping the tree into the central leader position. To maintain a trees size and form, prune heavily every three to five years: shorten scaffold branches, remove upper-most growing tips, any crossing or weak side shoots and all dead/weak wood. What’s the Best Time to Prune Walnut Trees? When is the best time for walnut tree pruning? It should have several moderately thick branches and be roughly 4–6 ft (1.2–1.8 m) tall. In fact, I expect more trees have been pruned during this time frame than all other times of year combined. The reasons for this are: If you are too late when pruning back your tree in the winter, the cut wounds will bleed. After about 1-2 years of growth, your walnut tree should have its basic form. The theory is to prune before the The professional world is merely divided on the best time at which to conduct the pruning. Walnut trees are prone to sap bleeding so it is imperative that any pruning is undertaken between mid-summer and early autumn. You should also observe that the younger branches of walnut trees are hollow. Dear Ms. S., you can prune back your walnut tree. Never hard prune a walnut tree: it will not tolerate it. First, cut halfway through the branch from the underside just outside the branch collar. Pruning of renewal: when the walnut trees reach their age (about 10 years old) they need to renew their branches, this is achieved with a more severe pruning than … Otherwise bugs will be attracted to the tree, which are likely to introduce diseases, putting the tree at risk. Prune the tree when it is 1-2 years old into the central leader position. After three years, the central leader and scaffold branches should be developed, giving the tree its form. After that, you want to completely cut off the branch further out (1 to 3 feet (0.5 to 1 m.)) on the limb.