Prepared by Lois Berg Stack, Extension ornamental horticulture specialist, University of Maine Cooperative Extension For information about UMaine Extension programs and resources, visit extension.umaine.edu. Find more of our publications and books at extension.umaine.edu/publications/. Table of Contents: Principles of Pruning Reasons for Pruning Pruning Techniques VIDEO: Pruning Ornamental Trees (YouTube) VIDEO: How to Prune a Lilac