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Structural Pruning

Pruning 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 & C: meaning remove Dead, Damaged, Diseased, Rubbing and Crossing branches to keep your tree healthy.

Structural pruning goals:

  • Remove dead or damaged branches
  • Select and develop a single, dominant leader
  • Select the lowest branches in your tree and remove branches below (important for conifers too!)
  • Well-spaced branches along the main trunk
  • Always make your pruning cuts outside the branch collar (the thick part oat 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 PlantAmnesty 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 PlantAmnesty'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. Check out this Arbor Day Foundation column on dormant season pruning.

Summer Pruning: Summer is a great time to remove watersprouts 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 watersprouts and suckers.

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 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 a 2” branch or larger 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.

Never top a tree
Topping a tree is not only ugly, it creates a hazard.

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.

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 PlantAmnesty to request an arborist referral.

More Pruning Resources

Pruning Information from PlantAmnesty
Pruning information from the International Society of Arboriculture
PlantAmnesty's referral service for Certified Arborists
City Fruit's Guide to Pruning Fruit 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)

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