Poor pruning techniques such as topping, shown here, won't make your tree smaller. Rather, it can spark rapid and abundant regrowth making your tree taller and less safe.
A tree that receives proper structural pruning when young will grow to be healthy and need less maintenance. However, trees are more often overpruned than underpruned. Keep in mind the 3Ds, R & C: meaning remove Dead, Damaged, Diseased, Rubbing and Crossing branches only to keep your tree healthy.
Improper pruning techniques seriously damage a tree. Consider hiring a professional certified arborist for the job. If you are going to do it yourself, there are several good resources to help you. And remember - never make a cut flush with the tree: always cut outside the branch collar - the thick part at the base of the stem.
Street Tree Pruning
Seattle Department of Transportation (SDOT) is responsible for maintaining the approximately 35,000 SDOT-planted trees located mainly along arterial streets. Care for all other trees in the street right-of-way is the responsibility of the adjacent property owner. If you or a former occupant of your home planted a tree along the street in front of your house, it is your responsibility to take care of it. Care includes watering in the drier season, mulching to conserve water and inhibit weed growth, and pruning to reduce conflicts with human activity, as well as to sustain the health and structure of the tree.
Pruning a 3” branch or larger on a tree (or removing a tree) located along the street requires a tree pruning permit from SDOT.
Don't top trees!
Pruning Guide from Seattle Department of Transportation – in 7 languages
Regional pruning guides from Plant Amnesty
Pruning information from the International Society of Arboriculture
Plant Amnesty's referral service for Certified Arborists