Master Plan Projects

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Supporting the enhancement of the Arboretum

Over the past 20 years, the Arboretum Foundation has conducted a number of targeted campaigns to help fund the Washington Park Arboretum’s comprehensive Master Plan, adopted in 2001.

Many major capital projects in the Plan have already been completed, including:

  • Duck Bay shoreline restoration (2005).
  • Installation of new irrigation mainlines to serve the entire Arboretum (2004 to present).
  • Construction of the new Japanese Garden Entry Gatehouse (2008 to 2009).
  • Phases 1 and 2 of the Pacific Connections Garden (2005 to 2013), including the Entry Gardens, Meadow, Cascadia Forest, Gateway to Chile, and New Zealand Forest.
  • Arboretum Loop Trail (2016–18).

Recent Projects Completed

high school-aged children posing with shovels on downed tree

Lake Washington Boulevard Corridor Project

In spring 2018, the Arboretum Foundation and its University and City partners launched a project to clean up and enhance the plant collections and natural areas along the Boulevard and Loop Trail corridors. The project was made possible by a generous gift of $275,000 we received from the Aldarra Foundation. Work crews from the Student Conservation Association (SCA) helped launch the project by spending four weeks removing blackberry and other invasive plants along Arboretum Creek.

The funding has allowed us to hire temporary gardeners, purchase necessary equipment, and install many new plants along the creek and at various locations along the Boulevard and Loop Trail corridor. The Arboretum’s prized Viburnum Collection along the Loop Trail has undergone a major revitalization and enhancement. The SCA returned every summer from 2019 – 2023 for more weeding work in the Pinetum and Loop Trail wetlands. And our generous donor renewed their commitment to the project with gifts of $100,000 in both 2019 and 2020.

New planting areas include the Holly Collection, Gateway to Chile, and various sites along Arboretum Creek. As of 2026, most of the new planting is complete, and the focus of the project has switched to maintenance and care.

Related Links

woodland garden with steep stairway and blooming rhododendrons

Restoring Rhododendron Glen

In spring 2019, the Arboretum embarked on a plan to restore one its most special and beloved places: Rhododendron Glen. The project was made possible by a generous gift of $750,000 from long-time Foundation volunteer Mary Ellen Mulder and her husband, Gordon Mulder.

Located near the south end of the Arboretum, Rhododendron Glen dates to the 1930s and has it all: dramatic topography, tall trees, a babbling brook, and beautiful understory plants, including many unusual species of rhododendron. Over time, however, important parts of the glen lost their luster. Weeds infiltrated; the canopy became too dense in places, resulting in a loss of understory plants; trails deteriorated and were negatively impacting the stream; and key sections of the stream and its associated rock work were overgrown or have silted up.

Since 2019, weeding, strategic opening-up of the canopy, and extensive new planting have had a transformative effect on the glen. Progress has also been made on the stream and pond restoration components of the project. Wetland and watercourse reconnaissance has been conducted in the larger glen area, and Berger Partnership was hired to develop the design. A pandemic-related backlog at the Army Corps of Engineers caused a permitting delay in 2020–21, however, the permits were acquired in summer 2022, and construction began in August 2022. The construction phase was completed later that fall. Intensive planting of the lower glen and restored stream took place from November 2022 through spring 2023, wrapping up the four-year restoration project.

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Restoring the Tsutakawa Memorial Gates

From 1976 to 2020, the Memorial Gates graced the north entry to the Washington Park Arboretum. Commissioned by the Arboretum Foundation, they were created by the artist George Tsutakawa (1910–1997) to commemorate all those who have loved and supported the Arboretum. On March 19, 2020, the Memorial Gates were stolen. The news was greeted with frustration and sadness by the many who appreciated the gates’ unique artistry and representation of place.

Shortly after the theft, a number of individuals contacted us to offer their support. We also met with the Tsutakawa family to discuss an effort to replace the Gates. We feel very fortunate to have Gerard Tsutakawa, who fabricated the original gates for his father, involved in the project. We set an initial goal of $150,000 to cover the cost of materials, fabrication, project management, site preparation, and gate installation. In August 2021, thanks to many generous donors, we surpassed our goal!

Gate fabrication took place in the spring and summer of 2022. Installation of the new gates took place in late summer 2022. A public celebration was held at the Graham Visitors Center on September 14, 2022.

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Centennial Summer Garden

In September 2017, the Arboretum opened its the Centennial Summer Garden to the public. Located by the pond at the south end of Azalea Way, the summer-themed garden celebrates the 100th anniversary of the Seattle Garden Club, which has a long and influential history in the Arboretum. It was created using a grant from the Garden Club, along with matching funds from the Foundation.

The centerpiece is a long, curving, stone bench offering views across the pond to the tree-clad hillside beyond. Hydrangeas are the summer-blooming stars of the show. Cultivars of Hydrangea macrophylla, H. serrata, and H. quercifolia lead the visitor through the garden. Calycanthus, Olearia, and Alangium round out the shrub layer, while plantings of rhododendrons and enkianthus connect the garden to the spring-flowering displays on Azalea Way.

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Arboretum Loop Trail

In 2013, the Arboretum Foundation—working with its partners in the Arboretum and Botanical Garden Committee—secured $7.8 million from the Washington State Department of Transportation as part of required mitigation for the effects of replacing the SR 520 Bridge. The funds were used to design and build a new multi-use trail on the east side of Lake Washington Boulevard and connect it to the existing Arboretum Drive to form a two-mile bike-and-pedestrian loop in the Arboretum.

The trail was designed by Berger Partnership, and the project included the partial daylighting of Arboretum Creek and restoration of the wetlands by the Birch Parking Lot. Construction began in early 2016 and was completed in late 2017. Hundreds of visitors came to celebrate the grand opening of the trail in April 2018. The trail improves access to hidden parts of the Arboretum collections and also provides a great new venue for recreation in our city.

Related Links

“Washington Park Arboretum’s New Trail to Reveal Hidden Treasures” (Seattle Times, cover story, May 5)

“Designing and Implementing the Arboretum Loop Trail” (Arboretum Bulletin, Spring 2015)

Ginko Biloba

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