THE SEEDS OF THE COMMUNITY GARDEN movement were planted in the counterculture of places like 1970s New York City, among “guerrilla gardeners”—daring green thumbs who didn’t always wait for permission to plant fresh fruits and veggies in neglected vacant lots. In the decades since, community gardens have become fixtures of public life in America. First Lady Michelle Obama even championed the movement, digging up the White House South Lawn and welcoming school kids to help plant crops in the new White House vegetable garden.

Today, these healthy, productive public spaces are growing faster than ever. According to The Trust for Public Land’s 2018 City Park Facts report, there are more than 29,000 community garden plots in parks in just the 100 largest US cities. That’s 22 percent higher than just a year ago, and a 44 percent bump since 2012, when the organization began keeping track.

For park nerds like me, the growth in community gardens is just one of the fascinating trends identified in this year’s City Park Facts report. Every year, The Trust for Public Land surveys public and nonprofit parks agencies in the nation’s 100 largest cities. We track down data on everything from each city’s total park acreage to philanthropic and taxpayer spending on parks to trends in park design, amenities, and uses. It’s a key resource for planners, park professionals, and anyone who wants to know how their local parks can improve.

When I’m not working to produce the City Park Facts report, you’ll find me with my hands in the soil at the Rose Kennedy Greenway in Boston. A lifelong gardener, I’m encouraged to see gardens take root in more parks, in more neighborhoods, and in more cities across the country.

Seeds may only need water and sunshine to grow, but the funding and policies around community gardens in publicly owned spaces are quite a bit more complicated. Across the country, volunteers, organizations, and agencies are finding ways to make gardens grow, forming lasting partnerships that have fueled the movement’s expansion.  I’m encouraged by the success of partnerships such as NeighborSpace in Chicago, which handles matters as diverse as funding, technical assistance, property acquisition, and tool lending. The city of Seattle runs the P-Patch program, which oversees 3,055 plots, making space for 6,800 gardeners. The all-volunteer Grow Northwest pitches in training, tools, and supplies.

There are hundreds of groups working to grow gardens in public parks across the United States. If you’re looking to volunteer, or want to start your own community garden, chances are there’s a local organization that will welcome your help.

The Trust for Public Land has a long history in community gardens. In the 1990s, we helped save dozens of neighborhood gardens in New York City from bulldozers. More recently, we helped create Frogtown Park and Farm in St. Paul, which is now among the largest urban demonstration farm in the country. And we’ve helped add numerous community garden plots to parks we’ve built or reinvigorated, creating a source of healthy food in neighborhoods where it can be hard to come by.

So we know that no matter who plants, maintains, and harvests a community garden, everyone reaps the benefits.  Researchers from University of Pennsylvania, Rutgers University, and Columbia University recently published a study linking community gardens and reclaimed vacant lots with improved mental health and reduced symptoms of depression and stress—especially in low-income neighborhoods.

Scientists hazard a number of factors could account for these findings: our brains may be hardwired to respond to nature, our bodies thrive when we exercise and spend more time outdoors, and our communities cohere and strengthen around shared public spaces like community gardens.

The study bears out a lesson I’ve learned time and again: spending time working the soil brings peace and happiness, and a renewed commitment to ensuring that everyone in America lives within a 10-minute walk of a park, garden, or open space.

Charlie McCabe is the director of the Center for City Park Excellence at The Trust for Public Land, a national non-profit that creates parks and protects land for people.