PruningTree pruning is essential for maintaining the safety and health of trees. A well-pruned tree will seal over the area and would not leave it exposed to insects or diseases. Therefore arborists from Guradian Tree Services use the perfect pruning cut at a 45-degree angle so the branch ridge and collar are not damaged.Trimming. A tree trimming project promotes the growth of trees and plants. It should be done at least once after a flowering season. It is great for the maintenance of city parks and personal yards.