Cass Turnbull began the Heritage Tree program in 1996 and joined with the city of Seattle a few years later, bringing the program from a celebration to a widely-respected designation honoring Seattle’s special trees.

In 2023, the city’s tree code was updated, giving special “Tier 1” protections to designated Heritage Trees.

Since this change to the program, Seattle’s Dept. of Transportation and PlantAmnesty have been unable to find a way to move forward with nominations and new HT designations, but conversations in 2026 are paving the way to the next steps.

What is a Heritage Tree?

• Heritage trees may be on either City or private property. Each candidate tree is assessed by a certified arborist and evaluated by a review committee. Trees can be nominated as an individual or a collection, but must have the owner's approval and meet criteria for health in addition to being selected according to one of the following categories:

  • Specimen: A tree of exceptional size, form, or rarity.

  • Historic: A tree recognized by virtue of its age, its association with or contribution to a historic structure or district, or its association with a noted person or historic event.

  • Landmark: Trees that are landmarks of a community.

  • Collection: Trees in a notable grove, avenue, or other planting.

• Submit your nominations on the Seattle Dept. of Transportation website