SAN FRANCISCO — All Tara Hui wanted to do was plant some pears and plums and cherries for the residents of her sunny, working-class neighborhood, a place with no grocery stores and limited access to fresh produce.
But officials in this arboreally challenged city, which rose from beneath a blanket of sand dunes, don't allow fruit trees along San Francisco's sidewalks, fearing the mess, the rodents and the lawsuits that might follow.
So when a nonprofit planted a purple-leaf plum in front of Hui's Visitacion Valley bungalow 31/2; years ago — all flowers and no fruit, so it was on San Francisco's list of sanctioned species — the soft-spoken 41-year-old got out her grafting knife.
"I tried to advocate for planting productive trees, making my neighborhood useful, so people could have free access to at least fruit," she said. "I just wasn't getting anywhere."
Today, Hui is the force behind Guerrilla Grafters, a renegade band of idealistic produce lovers who attach fruit-growing branches onto public trees in Bay Area cities (they are loath to specify exactly where for fear of reprisal).
Their handiwork currently is getting recognition in the 13th International Architecture Biennale in Venice, Italy, as part of the U.S. exhibit called "Spontaneous Interventions: Design Actions for the Common Good." Closer to home, however, municipal officials have denounced the group's efforts.
Even the urban agriculture movement is torn when it comes to the secretive splicers, outliers in a nascent push to bring orchards to America's inner cities. While many applaud their civil disobedience, others fear a backlash against community farming efforts. And few believe their work will ever fill a fruit bowl.
Not that that really matters.
"It's like the gardener's version of graffiti," said Claire Napawan, assistant professor of landscape architecture at UC Davis and a grafters sympathizer. "Even if there's some question about its ability to produce enough food to make a difference ... as an awareness piece, it's a good idea."
On a sunny day toward the end of summer, Hui was bent over an immature tree, searching for the tell-tale strip of electrical tape that would show where a fruit-producing branch had been spliced onto an ornamental plant.
The small stand of cherry trees had been transformed during the most recent grafting season, late winter to early spring, using a simple method that Hui described as being "like tongue and groove in carpentry."
First a slit is made in the host tree. Then the alien branch is whittled into a pointed wedge. The grafter inserts the wedge and matches up the elements' nutrient-transporting layers before securing the area with tape. The Guerrilla Grafters use electrical tape instead of grafting tape so they can color code their work for future reference.
"Once it heals, it connects," Hui said. "Basically the branch becomes part of the tree.
The group only grafts trees that are nominated by a steward in the neighborhood, who promises to maintain it and make sure that fruit is harvested and does not become a hazard. Trees also are grafted within species, fruit-bearing apple onto ornamental apple, for example.
If all goes well, in several years grafted branches will blossom and bear fruit. Of the 50 or so trees Guerrilla Grafters has transformed, Hui said, a few already have produced fruit, including an Asian pear whose location she would not disclose.
"Two months after we grafted it, it flowered, and we went back again and saw little pears on it," she said. "Some passers-by must have picked it and had it, which is the idea. There's no ownership of these trees. There's just stewardship."
The Guerrilla Grafters are as cagey about attracting members as they are about safeguarding the group's operations. There is a Facebook page, and prospective grafters "contact us for the most part," Hui said. "It's a little tricky. We just want to be careful."
It was a lesson learned the hard way.
On Feb. 18, a grafting project was announced on Facebook: "Hayes Valley Farm today at 1 pm — Laguna b/w Fell and Oak." Two days later, the website said that "all the viable grafts on those trees were gone. ... The trees were so severely pruned, they even look kind of sad."
The group suspected city gardeners were behind the "vandalism" and beseeched them to be kinder in the future: "Whether or not you agree with what we do," the post said, "please trust that we care about those street trees as much as, if not more than you do. ... We respect your hard work, please allow greater participation in caring for our public space."
Carla Short, San Francisco's urban forester, said that no one in the Department of Public Works had "formally" removed any of the guerrilla efforts performed by the group of 30 or so grafters.
If the city's tree crews come upon a grafting, they have been instructed to report it to her, and "we'll take it on a case-by-case basis." Street trees are allowed by permit only, and the city will not grant a permit for an apple, plum, pear or any other fruit producer.
"We really support growing fruit trees in the right places," Short said. But "we don't want people to get hurt, and we don't want to damage our already vulnerable street trees."
Community gardens have prospered for decades on vacant lots in cities around the country. But urban orchards — which require a greater investment, particularly in time — have only begun to catch on in recent years.
That commitment is part of the allure to the many romantics in the urban orchard movement. If a tomato plant is a summer fling, they figure, then a fruit tree is more like a marriage.
"You can have a relationship over time with a tree," said Lisa Gross, founder of the Boston Tree Party, which has planted 110 apple trees in civic spaces over the last year and a half and is planning its first harvest celebration in 2015. "We all love tomatoes, but you put it in and pull it out at the end of the season."
Most urban orchards are created with at least some municipal cooperation. The Philadelphia Orchard Project, launched in 2007, has planted 449 fruit trees in partnership with the city water department. The Beacon Food Forest, which will break ground later this month, was developed on seven downtown acres owned by Seattle Public Utilities.
Ornamental street trees that are not bearing fruit "should be abolished," said David Burns, who co-founded Fallen Fruit and is working on the park project with the L.A. County Arts Commission. "That should be just not legal."
In a South of Market conference room, four members of the Guerrilla Grafters hunched over their laptops, working on the next phase of their sweetly subversive project.
Using data available online, they hope to pinpoint every one of the approximately 103,000 street trees in San Francisco that might be turned into a fruit producer. They also plan to map every grafted tree to aid in care, future harvesting and research into which species work best in the city's varied microclimates.
The prototype maps look like abstract watercolors, and the database lists each tree's location by latitude and longitude, as well as its scientific and common names. For a select few, there is a notation about what was grafted on and when.
After a decade working in high-tech, software developer Jesse Bounds, 35, took a year off and traveled the world with his wife. They volunteered on a vineyard in Italy, helped create water filters and stoves for South American villagers and lent a hand to Elephant Human Relations Aid in Namibia.
To Bounds, who has also grafted with the guerrilla group, the database is "software development work with a clear connection to the real world."
Hui also was trained as a computer scientist, but left the industry years ago to dedicate herself to the causes that she said matter: social justice, sustainability and community.
Her day job is with a nonprofit organization called Kids in Parks, where she teaches outdoor science classes to middle-schoolers on a part-time basis. With the help of a friend, she designed and built the Poo Garden, a prototype composting toilet that, when full, becomes a planter.
Hui said she works hard "to be less dependent on money." She barters and trades with friends. She keeps backyard chickens and eats from her home vegetable garden.
She dreams of cities filled with fruit trees.