Design Complete on Four Seasons Arboretum

GreenWorks just completed the Master Plan development and design drawings for the City of Gresham’s new Arboretum at Gradin Sports Park including trees and shrubs that will showcase seasonal interest and the local nursery industry.


The Arboretum will provide significant educational opportunities for residents of the City of Gresham and region. It will be a place where people can learn about different trees and observe their unique qualities. Over time, the city will be able to monitor and document how particular trees grow and function in specific locations. This learning landscape will provide a valuable tool for future City projects, helping others select the right tree for the right use.


In September 2009 the City of Gresham held an Urban Forestry Community Forum and identified Gradin Community Sports Park as a potential location for a city arboretum. The 33-acre park, adopted in January 2008, was partially developed and landscaping had not yet taken place. City requirements for street trees and buffering provided the framework for the arboretum design. To solicit further input on the design of the Arboretum at Gradin Community Sports Park, a Tree Forum was held on March 13, 2010. The Tree Forum developed clear goals and objectives resulting in conceptual planting schemes, including a list of possible tree collections. With this groundwork in place, the City of Gresham hired GreenWorks to design an arboretum that incorporated goals and objectives from the Tree Forum into a final arboretum design.


The Four Seasons Arboretum creates four internal nodes that feature tree collections with seasonal interest. The collections showcase species for their unique qualities during that particular time of year; for example, the winter tree collection includes various cultivars of Witch Hazel (Hamamelis x intermediaknown for its small star-shaped bloom as well as the Snakebark Maple (Acer davidii) noted for its stripped green bark prominent in the winter. A Children’s Arboretum is situated in the middle of the winter tree collection highlighting playfully drooping and dwarfed trees. As the Sports Park is built out over the years, the Children’s Arboretum may include other features besides trees that would contribute to the designation as a children’s arboretum and natural play area.

The tree species included in the seasonal tree collections are appropriate for residential use and demonstrate to the public a diverse set of tree species available at local nurseries. The entire arboretum illustrates the vast number of tree species cultivated and grown locally. Additional specialized collections supplement major plantings. These include collections of urban lot trees, wetland trees, native wetland trees, conifers, shade trees, street trees, columnar street trees, and natives appropriate for parking lots. The northern and western perimeter plantings feature landscape buffers of conifers and deciduous trees supplemented with shrubs and groundcovers.


The arboretum also includes four signature trees accentuating key elements or connections in the Sports Park. The Four Seasons Arboretum incorporates a pair of contrasting signature trees to accent the main entry way into the parking lot. Here Hogan Cedars (Thuja plicata ‘Hogan)’ are arranged in a semi-circle as a backdrop for a row of Flowering Dogwoods (Cornus ‘Eddie’s White Wonder’). Signaling the public entryway this form is repeated with Emerald Avenue Hornbeam (Carpinus betulus ‘Emerald Avenue’) serving as a backdrop to the Flowering Dogwood. This combination is repeated, framing the pathway running north and south between the west and east soccer fields. A double row of Yellow Magnolia (Magnolia ‘Elizabeth’) flanks the pedestrian crossing in the parking lot connecting the spring and fall tree collections. The Yellow Magnolia has both spring interest and fall interest and provides a strong link between the two collections.

The arboretum will be constructed in phases as the sports park is developed. The first phase includes the entry, Palmquist street trees, and northern buffer. The arboretum at Gradin Sports Park will be a beautifully unique place where Gresham citizens can learn about and enjoy the wide range of trees that thrive in the northwest.