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Structural Pruning

Pruning young trees to build strong structure is critical to growing a healthy mature tree and avoiding dangerous or unsightly limb loss. Taking simple steps while the tree is young can prevent costly pruning in the future. Keep in mind the 3Ds, & R : meaning remove Dead, Damaged, Diseased, and Rubbing branches to keep your tree healthy.

Structural pruning goals:

  • Remove dead or damaged branches
  • Select and develop a single, dominant leader
  • Select the lowest permanent branches in your tree and remove branches below (Don't remove them all in one year)
  • Well-spaced branches along the main trunk
  • Always make your pruning cuts outside the branch collar (the thick part at the base of the stem), never make a cut flush with the tree.

Here are a few great structural pruning resources:

Interested in gaining some hand-on experience with the pros? City Fruit, UW Botanic Gardens, and Plant Amnesty all offer hands-on structural pruning courses in Seattle. Learn more by visiting their webpages and contacting them about their upcoming class schedule

Improper pruning techniques seriously damage a tree. Consider hiring a professional certified arborist for the job. Check out Plant Amnesty's arborist referral service.

Pruning Timing

Winter Pruning: Prune your tree in winter while the tree is dormant to encourage a burst of new growth in spring. Pruning in winter when deciduous trees have lost their leaves makes it easier for you to visualize your tree's form and make decisions about what pruning cuts will improve structure. When pruning flowering trees, be careful not to remove flower buds. Be sure to wait until after the winter solstice to avoid the pitfalls of fall pruning. Pruning in the fall should be avoided as there are more decay fungi spores in the air and pruning wounds are slowest to close at this time.

Summer Pruning: Summer is a great time to remove water sprouts and suckers growing from the tree's rootstock. Summer pruning helps suppress growth, which is why this is a great time of year to remove those pesky water sprouts and suckers.

Street Tree Pruning

Seattle Department of Transportation (SDOT) is responsible for maintaining the approximately 40,000 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 dry 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 branches larger than 2" or which compromise more than 15% of foliage bearing area on a street tree requires a free tree pruning permit from SDOT. For more information about pruning trees in the right-of-way, contact the SDOT Arborist's Office at Seattle.Trees@seattle.gov or 206-684-TREE(8733).

For a list of Seattle tree service companies with an SDOT Annual Permit to work on street trees, click here.

Stop Tree Topping

Tree topping is an outdated pruning practice that indiscriminately removes large amounts of leaves and branches. Not only does tree topping look terrible, it will cause greater and faster regrowth. Topping a tree only stimulates growth, increasing the need for subsequent work and maintenance. Tree topping also causes serious long-term damage to a tree, increasing the hazard to people and property. Certified arborists and legitimate landscape professionals will never suggest topping a tree- there are other acceptable pruning practices for keeping a tree away from adjacent structures. Avoid tree topping, and hire an ISA certified arborist. Check out this ISA article on Why Topping Hurts Trees.

Why Hire an Arborist

Certified arborists are experts in tree health and care and are knowledgeable about what a tree needs to thrive. Arborists are a great resource for determining the care your tree needs, such as the pruning required to improve the health, appearance and safety of your tree. Worried about a pest or disease affecting your tree? An arborist can help diagnose the problem and determine a plan to address the issue. An arborist can also determine the potential hazard of a tree in your yard and help you make an informed decision about how to manage.

If you are hiring a professional for tree services, always confirm that they are an ISA Certified Arborist. Need help finding an arborist? Contact Plant Amnesty to request an arborist referral.

Additional Resources

Pruning Information from Plant Amnesty

Pruning Mature Trees

Plant Amnesty's referral service for Certified Arborists

City Fruit's Guide to Pruning Fruit Trees - Do not apply these principals to shade and ornamental trees

SDOT's Online Street Tree Map- Helpful if you are unsure about street tree ownership and maintenance responsibility

Why Hire an Arborist

Annual Tree Pruning Steps from Planting to Maturity (Arbor Day Foundation)