The Children’s Garden of the Arboretum at Fort Williams Park in Cape Elizabeth is a throwback – not to gardens of the past but to a type of childhood that has largely disappeared.

“When we were younger we would spend time wandering through woods and creeks, and children don’t do that as much now,” said James McCain, arboretum director. “Kids have so many organized activities that they don’t have time for unstructured play. This site has lots of areas to roam and play and enjoy a natural setting.”

When I joined a group of volunteers spending a late August morning planting 1,800 native plants in the garden, my first reaction was that in the future, many young visitors will be going home with wet, muddy clothing.

That’s because the hillside garden’s most dramatic feature is a 200-foot stream that runs downhill from the newly created frog pond. Must-be-walked stepping stones in a Y shape cross the pond, and garden paths lead right up to the stream, where youngsters may accidentally – or perhaps accidentally on purpose – fall in.

Which is fine, according to the builder of the pond and stream. “We designed it to be pretty rugged,” said Christopher Paquette of Robin’s Nest Aquatics. The pond and stream are lined with two layers of reinforced polyvinyl liners. Paquette himself placed more than 50 tons of stones on top of the liners so the stream would look natural. No easy task.

“I walked seven miles and got more than 60 flights of stairs that day” as measured on a Fitbit, Paquette said.

The water for the frog pond and stream is pumped from a pre-existing skating pond. The aquatic plants in the frog pond will filter the water and help clean up the skating pond, which is home to many invasive goldfish.

The garden, designed by Sashie Misner of Mitchell & Associates Landscape Architects in Portland, offers plenty of other places for children to experiment and explore, as well, including a tree house, two tunnels and uneven natural stone steps. Also, an area has been set aside for a fairy village.

But fun as these features are, it is mostly about the plants – 5,690 of them, McCain said, which came from an assortment of local and regional nurseries, a board member of the Wild Seed Project and generous homeowners, who dug up hundreds of their own plants to donate to the project.

Different areas in the new Children’s Garden represent the Eastern forest, with mostly oaks and huge stumps where invasive Norway maples were removed; a pollinator meadow; and sections with low-bush blueberries, hay-scented fern and a native sod made from sheep laurel and wintergreen. Throughout the garden, soil that would usually be considered poor quality was used, both to encourage native wildflowers and to discourage weeds.

Opening ceremonies for the Children’s Garden were held on Friday, but that doesn’t mean it’s complete – if you can ever call a garden complete. It’s slated to get more small perennial seedlings, buckwheat to prevent weeds and erosion, and additional aquatic and marginal plants for the pond and stream. Although it typically takes about three years for a newly planted perennial garden to fill in, McCain expects the Children’s Garden to look attractive as early as next year.

The cost of construction came to $375,000 – donated labor and materials kept it from being higher – and additional money has been set aside to buy more plants and maintain the space over the next four years. Volunteers tend to all the gardens in the 90-acre Fort Williams Park, which keeps expenses down.

The fun and learning opportunities for children make it worth it, McCain believes.

“This garden is designed to be a safe oasis, where we can have children engaged in nature, appreciate and learn about nature,” McCain said. “They can study butterflies and honeybees and learn a bit about the stewardship of the world around them.”

The Children’s Garden is the third completed garden of more than a dozen proposed as part of the Fort Williams Arboretum, following the Cliffside and Lighthouse View gardens. Work has already begun on Cliffside Walk, which will connect the Cliffside and Lighthouse gardens, McCain said. To a large extent, that project will consist of controlling invasive plants, such as bittersweet and swallowwort, and letting the natives and other noninvasives grow in a kind of natural succession garden.

Once that’s completed, the adults can have their quintessential Maine views without the invasive plants in the most visited part of Fort Williams Park, and the children will have their private 1.5-acre hideaway in what previously was a seldom-visited section.

Tom Atwell is a freelance writer gardening in Cape Elizabeth. He can be contacted at 767-2297 or at: tomatwell@me.com.