Trees are generally trimmed for one of three purposes: aesthetics, safety or health. Aesthetics – Pruning a tree effectively helps to maintain its shape and appearance. However, you shouldn’t try to impose an unnatural shape or size on a tree. The amount of trimming and pruning that will be needed could seriously damage it. Safety – Dead or broken branches and limbs can fall off at any time, which is a serious safety hazard. If the branches of a tree obstruct your vision while driving, they should be trimmed away. Finally, tree limbs and branches occasionally grow too close to utility lines.