The Arboretum Foundation, a dedicated non-profit since 1935, champions the stewardship of Washington Park Arboretum. It actively raises funds, advocates for, and manages robust membership and volunteer programs. Since 2016, the Foundation has also overseen fundraising and cultural initiatives for the Seattle Japanese Garden. Key events include the annual gala at the NW Flower & Garden Festival and monthly programs in the Japanese Garden, spotlighting Japan's cultural heritage. Membership benefits encompass a quarterly magazine, guided tours, and exclusive retailer discounts.