The Heritage Tree Program was started by PlantAmnesty in 1996 to celebrate Seattle's special trees. The City of Seattle joined the effort a few years later. In 2017, administration of the program was handed over to The City of Seattle Department of Transportation, but PlantAmnesty still plays a role in the program by evaluating Heritage Tree nominees once or twice a year and selecting those that meet the definition of truly exceptional trees.

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.

Each Heritage Tree owner receives a certificate. For trees that are viewable by the public and the homeowner wishes to commemorate the tree with a plaque, PlantAmnesty will reimburse part of the homeowner's cost. Homeowners may wish to have a dedication ceremony for their Heritage Tree, in which case, a member of PlantAmnesty's  staff or a volunteer may be available to help officiate.

If you have a significant tree and are interested in having it evaluated for Heritage Tree status, please go to the Seattle Department of Transportation Heritage Tree Program website.