History of the Arboretum
A celebrated Olmsted park and botanic garden
Washington Park Arboretum has a long and complex history. Prior to white colonial settlement, the land was home to Coast Salish people, who had several villages in the Union Bay area. Towards the end of the 19th-century, it was owned by the Puget Mill Company, which logged the land’s large trees in the 1880s. In 1900, the site became a city park, Washington Park (one of Seattle’s first), and was home to a speedway for horse racing and a sanitary fill.
In 1903, the Olmsted Brothers Landscape Architects firm created the design for Lake Washington Boulevard, which weaves through the present-day Arboretum, as part of its comprehensive plan for Seattle parks and parkways. Washington Park remained largely undeveloped in the 1910s and 1920s.
Interest in creating an Arboretum in Seattle had been brewing for three decades among staff at the University of Washington and members of the community. The Arboretum was officially established in 1934. The following year, the Arboretum Foundation was formed to raise funds for the nascent botanical garden. In 1936, thanks to a donation from the Seattle Garden Club, the Olmsted Brothers were hired to create a design plan.
With the Great Depression in full swing, much of the early construction and planting work in the Arboretum was carried out through the Works Progress Administration. The speedway became Azalea Way, one of the central features of the Arboretum. In the decades to come, especially under the tenure of Brian Mulligan (director from 1945 to 1972), the Arboretum’s plant collections developed, flourished, and grew to what you see today.
Further Reading
- HistoryLink, a free online encylopedia of Washington State history, also published an excellent short history of the Arboretum in January 2013.
- Read a detailed historical review (PDF 12.0 MB), commissioned by the Arboretum and Botanical Garden Committee in 2003 and co-authored by BOLA Architecture & Planning and Karen Kiest Landscape Architects.
- Check out our Fun Facts about the Arboretum, including a historical look at this space and its many visitor attractions over the years.
Black Walnut Tree in Arboretum Tests Positive for Thousand Cankers Disease
Oct 15, 2026
Cankers and beetle feeding holes on the inner bark of a downed walnut branch. (Photo courtesy: Elizabeth Bush, Virginia Polytechnic Institute and State University, bugwood.org)FIRST DOCUMENTED CASE IN WESTERN WASHINGTON! This summer, Seattle Botanic Gardens...
Hidden Treasure of the Arboretum: Witch-Alder
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Fall foliage close-up of a witch-alder in the Arboretum's Woodland Garden. (Photo by Niall Dunne)BY PHIL WOOD As a retired garden designer, I am always on the lookout for plants that offer multiple seasons of interest. Witch-alders (Fothergilla species and hybrids)...
Volunteers Help Host First Seattle Botanic Gardens’ Plant Sale
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Volunteers helping shoppers at check-out in the Big Greenhouse. (Photo by Polly Teeter)BY ALICIA HAMILTON Our annual Fall Plant Sale took place at the Graham Visitors Center in the Arboretum last Saturday, September 19. Though it happened on a single day, the sale was...

