“Let’s throw some bombs,” a young woman calls out, waterproof floral purse swinging on her shoulder and Laura Ingalls braids flying behind her as a band of 25 followers cheer, “Cool!”

They rush toward a drab vacant lot in Shaw. Some climb up onto the back of a truck to get better aim at their target. But these bombers aren’t likely to appear on any terrorist list or even get arrested. They’re throwing “seed bombs,” golf-ball-size lumps of mud packed with wildflower seeds, clay and a little bit of compost and water, which they just learned to make at a free seed-bombing workshop for Washington’s guerrilla gardeners.

The benign bombing is part of a larger phenomenon known as activist gardening that is taking off this spring in cities such as Portland, Detroit, Baltimore and the District, where young urbanites are redefining the seemingly fusty pastime as a tool for social change. This is civil disobedience with a twist: Vegetable patches and sunflower gardens planted on decrepit medians and in derelict lots in an effort to beautify inner-city eyesores or grow healthful food in neighborhoods with limited access to fresh food.

“Guerrilla gardening is urban gardening and food justice. It’s just this really cool mix,” says Emmy Gran, 25, who is teaching seed-bombing in a floppy sun hat at a recent Saturday morning workshop in the courtyard of Old City Green, a gardening store in Shaw. “But it’s controversial, too. If you see an abandoned, neglected lot and you decide to do something about it by planting vegetables and herbs, are you an occupier? It’s kind of radical, in some ways.”

And every radical movement needs graffiti. Gran hauls out her Cuisinart to make the green “spray-paint” required for gardening activism’s biodegradable moss graffiti. Ingredients: moss, a half teaspoon of sugar and beer or yogurt which, when blended, will stick to walls. (“You can also use buttermilk,” she adds.) With a light rain starting to fall, the group walks over to a curb near the garden store and uses the gloppy mixture to write “Nourish, Grow, Shaw” in big, moss-green letters.

Activist gardening is the latest face of social justice in the District. Forget living in a tent in McPherson Square. Instead, try pulling on muddy work boots and hauling fertilizer and mulch to a forlorn lot, then persuading your housemates to get off their iPads and go outdoors to plant snap peas and garlic. The group at the workshop includes former Peace Corps volunteers, environmental activists, plaid-ensconced hipsters and social justice workers, all eager to learn more about subversive or sneaky gardening, as it is also known.

“It’s all a lot less devious than it seems,” says Ellen Abramowitz, 22, who works for the Alliance to Save Energy, a nonprofit group that educates schools about energy efficiency. “Besides, who doesn’t love flowers?”

One flower at a time

Gran tells her students — most of whom were born in the 1980s — that guerrilla gardening dates from the late-1960s establishment of People’s Park in Berkeley, Calif., when a disused patch of land near the University of California campus was co-opted by the community and reimagined as a public green. Today, she says, it takes place in more than 30 countries, with much of the activity documented on the British-based Web site guerrillagardening.org. It has spread in the United States in recent years, spurred by the “green” movement and the increased demand for locally grown, healthful food.

“I think it’s also a democratic statement and an experiment in re-creating space,” says Columbia Heights environmental consultant Tristanne Days, 24, as she carefully assembles seed bombs. “We’re making the city what we want.”

They’re doing it one flower at a time. The bombs will — in theory — bloom into bachelor’s buttons and baby’s breath, forget-me-nots and marigolds when the truffle-size balls hit, then expand. It also helps if there’s a healthy spring rain, said Scott Aker, head of horticulture for the U.S. National Arboretum. If the bombs are launched into a sunny space where there’s not too much other vegetation present, then he gives the seeds a 70 percent chance of blooming. “But either way, it sounds like great fun,” Aker says. “On your commute, you can toss one out the window.”

District police say that guerrilla gardening technically constitutes unlawful entry, a misdemeanor. But, says D.C. police spokeswoman Gwendolyn Crump, “nothing like this has come to our attention.” Although there have been reports of gardens being bulldozed to make way for development, gardeners say the issue of small-scale gardening is typically hashed out between property owners and the people doing the planting.

Permits for planting

Not everyone at Gran’s workshop is a guerrilla gardener. Some of the young people attending the class — run by Knowledge Commons D.C., an organization that provides free public workshops on a variety of subjects — have secured permits for their plots.

This spring Sarah McLaughlin, 25, and her boyfriend Josh Singer, 31, started a community “parken” on a 2.7-acre parcel of unused land north of Howard University. They named it Wangari Gardens after Wangari Maathai, the Nobel Prize-winning Kenyan environmental activist. (Although it took months, Singer was able to obtain a public-use permit from the Department of Transportation, which oversees the land, to garden there.)

“We’re a real D.C. love story,” McLaughlin says with a laugh as Singer puts his soil-stained arm around her after a long day of gardening. The couple fell in love at the Occupy D.C. camp in McPherson Square, where they were both living this past fall. Singer works for D.C.-based nonprofit group Casey Trees, which helps local schools and urban communities plant trees. McLaughlin is a manager for Old City Green and teaches an after-school garden and nutrition program at D.C. Prep Public Charter School in Northeast.

“We saw the land near where we have a group house, and we wanted to use green space to build community,” says Singer, who’s wearing an “I Dig Trees” T-shirt under his Carhartt jacket. So far, McLaughlin and Singer have helped the community plant 59 garden plots in Wangari Gardens, each tended by neighbors who live nearby and pay annual dues to grow food and flowers in a raised garden bed with advice from experienced gardeners. (On a recent visit to Wangari, several longtime residents said they were happy with the garden because the land had been vacant for so long.)

Singer has put $3,000 in soil and other supplies on his credit card. But he hopes the garden will flourish and that he will eventually obtain sufficient funding and grants to add a dog park, a butterfly/native plant garden and an outdoor classroom. On Sunday, Wangari will host a Repurposing Space Day to showcase ways that local organizations can reuse vacant or underutilized land in the District.

“There’s just so many really cool gardening projects going on around Washington,” Singer says. “It’s a great moment.”

An urban phenomenon

During Wangari’s creation, the pair sought advice from Dennis Chestnut, 63, whom they see as the father of the District’s activist gardening scene. He is founder and executive director of Groundwork Anacostia River D.C., a nonprofit group that seeks to reclaim vacant and neglected land for conservation, recreation and economic development. He helped start two community vegetable gardens in wards 7 and 8, “in places where convenience stores typically sell alcohol and chips,” he said.

Chestnut says he’s proud that the young people in Washington are suddenly so interested in gardening. “Go to sleep one night and wake up, and there’s corn growing in the derelict lot by your check-cashing store,” he laughs. “I’m all for all of it: guerrilla gardening, community gardens. These young people living in D.C. are just go-getters. But I’m also a child of the ’60s. I understand it’s really important to organize all of us so we can work on common issues.”

There’s so much new community gardening going on in the District, he says, that it’s tough to keep track. Some takes place under the auspices of nonprofit organizations. City Blossoms works with D.C. public school students to beautify city spaces and grow, harvest and prepare vegetables; the Common Good City Farm is an education center that teaches low-income residents how to grow their own healthful food. More often, though, activist gardening is undertaken by friends or neighbors who seed-bomb potholes or trash-strewn lots.

Although activist gardening is largely an urban phenomenon, there are self-described “suburban guerrilla gardeners” in Arlington County and Alexandria, Wheaton and Gaithersburg who have organized meet-ups online. They describe stealthily turning empty spaces that abut strip malls, highways and parking lots into verdant flower and herb gardens. Eco City Farm in Edmonston has a trainee program that teaches immigrants urban farming — from composting to harvesting to marketing — so they can sell produce to farmers markets. Gran, who lives in Olney, says she recently engaged in clandestine wildflower-planting along a number of country roads.

Chestnut is working with City Council member Tommy Wells (D-Ward 6), who wants the city to develop a permit process for community gardening and provide an inventory of vacant District land that could be used for community gardens. He also hopes to provide the gardens with better access to water. “I see guerrilla gardening more as a byproduct of a city that can’t provide the support and assistance to residents that want to establish community gardens,” Wells said. “The city shouldn’t make it this hard.”

Not everyone shares Wells’s enthusiasm. A recent forum on the neighborhood blog Prince of Petworth prompted responses from posters who warned that vegetables grown near roads with heavy traffic could be toxic. Others wrote that guerrilla gardening — which sits at the nexus of gentrification and environmentalism — was an example of overly exuberant gentrifiers hoping to take over neighborhoods that may not want to change.

But the young people at Gran’s workshop say guerrilla gardening is making Washington a more progressive city. They gather after the workshop and talk about planning an outing on May 1, which has been declared International Sunflower Guerrilla Gardening Day online by a group of gardeners in Brussels that wants people all over the world to engage in the possibly illegal act of planting sunflowers on neglected land.

Guerrilla gardeners say every day is sunflower-planting day. “When you live in the city and you see a space that’s yucky, you can make it more beautiful,” says Theresa Blaner, 33, who writes the blog D.C. Guerilla Gardeners. Like most guerrilla gardeners, she’s never been arrested for it.

“But it would be awesome to have a [police] record for gardening,” she laughs.