Can I prune or ‘reduce’ a walnut tree?

Question

I planted the walnut tree several years ago at the bottom of my garden not realising how tall and wide it would grow. It produces quite a lot of nuts. I don’t want to chop it down, just reduce its reach as its leaves drop over the fence and it blocks light to the garden when in leaf. Help!? Thanks, Helen

Answer 1

The short answer is yes, you can lightly or moderately reduce the height and spread of a walnut tree without harm if done properly with horticulturally correct pruning methods. But major crown reduction, topping, with stub cuts will do more harm than good.

The more complete answer is that you should seriously consider how much crown reduction is needed and how this will be done. There are consequences with severely altering the natural form and beauty of a tree.
Consider hiring a professional, a certified arborist, who can assess and offer recommendations for "moderate crown reduction pruning" (25% maximum is the rule of thumb for Best Management Practices, and even that is a lot.) Or consider entire tree removal if the reduction indicated and possible annual maintenance pruning is not going to be satisfactory.

https://www.gardeningknowhow.com/edible/nut-trees/walnut/how-to-prune-walnut-trees.htm