Related Businesses If you own a garden with trees, sooner or later you'll be forced to dig out your tools and do a little pruning. Reasons to Prune a Tree Pruning may be required for a number of reasons: To remove branches that are diseased or damaged. For aesthetic purposes. To trim the height of the tree. To improve light penetration and air circulation by thinning the tree out. The Best Time to Prune Though diseased branches should be removed whenever they occur, pruning to change the shape of a tree or to reduce its height is best done when the tree is in its dormant period -- generally, late autumn or winter. Pruning when the tree is dormant reduces sap loss and minimises the risk of insect or fungus attacks. The Branch Collar Look closely at the branch you want to remove. Around it, where it joins the trunk, you'll see a slight bulge in the bark. This is known as the branch collar . When pruning, all cuts should be made on the branch side of this collar, never into the collar or directly flush with the trunk. Cutting into the branch collar will damage trunk wood and cause unneeded trauma to the tree. How to Cut Other than direct cutting, the branch collar can be damaged by tearing branch wood and bark. To avoid this during pruning, follow the cutting steps below. Using a pruning or bow saw, make a cut about 12 cm out from the