Pruning a twenty year old walnut tree to keep it a reasonable size to garden.
Certified GKH Gardening Expert
Pruning older walnut trees can be a little tricky, but it can be done. They should be pruned at anytime they are dormant, and have no leaves.
This article will help: https://www.gardeningknowhow.com/edible/nut-trees/walnut/how-to-prune-walnut-trees.htm