The Parks and Greenery department is responsible for parks, cemeteries, playgrounds, monuments, athletic fields, public docks, and acres of public green spaces. The department also maintains an urban forest of greater than 10,000 trees.
The Arbor Day Foundation has recognized Portsmouth as a Tree City USA for over twenty years. The Tree City USA program is sponsored by the Arbor Day Foundation in partnership with the U.S. Forest Service and National Association of State Foresters. Portsmouth achieved Tree City USA recognition by meeting the program’s four requirements: a tree board or department, a tree-care ordinance, an annual community forestry budget of at least two dollars per capita, and an Arbor Day observance and proclamation.
In 2019 the Parks and Greenery Department also received The Arbor Day Foundation's Tree Growth Award; this was based on the Department’s high-achieving levels of education, partnerships, planning and management, and tree planting and maintenance. Portsmouth and Nashua were the only communities in New Hampshire to receive a Tree Growth Award.