The Portland Museum of Art will improve its sculpture garden along High Street and open the garden to the public beginning in 2017.

The park is now closed except for special events, including the annual lighting of the Copper Beech tree each December. Next summer, the gates on High Street will be open, and the park will be improved to create a free, year-round public green space in the Arts District. The improvements are being funded with a donation from Maine businessman David Shaw of Scarborough, and the park will be named in his family’s honor.

Shaw, the founder of Idexx Laboratories, is a longtime museum benefactor and collector of sculpture. The museum declined to say how much Shaw gave.

The gift “accelerates” the museum’s plans to add more sculpture in 2017, according to a museum press release. Additional sculpture will be announced later, said museum spokesman Graeme Kennedy.

The project is part of the museum’s plan to make its buildings and collection more accessible to the public while also improving the public space around Congress Square. In May, it installed John Bisbee’s “Hearsay” in the garden. Made with 12-inch spikes, the piece represents a giant cone. It joined outdoor sculpture by Celeste Roberge and Sir Anthony Caro. In addition to the art in the sculpture garden, the museum installed Robert Indiana’s “Seven” in Congress Square in 2014.

With the sculpture park expansion, the museum will join the Farnsworth Art Museum and the Ogunquit Museum of American Art as Maine museums with free, permanent outdoor sculpture gardens on the grounds. The Art Gallery at the University of New England also has a sculpture garden with rotating works.

In the press release, Shaw said he was motivated to make the donation because it was a way to improve both the museum and the city.

“We do this with great appreciation of the benefit of art to society,” he said. “This park will provide public access to an artistic oasis in a cultural center of our community.”