No one is suggesting turning Boston Common into a farm, but there are a lot of smaller plots around. Estimates of the aggregate of small vacant plots vary widely, from 600 to a few thousand acres. Many are simply pieces of land that have lain unused for decades. “Those vacant lots are mostly in Roxbury, Dorchester, and Mattapan,” Connors points out. Not coincidentally, that is where City Growers is concentrating its efforts.

The potential is staggering. “Take 10 percent of that,” says Lloyd, “or even 5 percent. That would produce a checkerboard of small intensive farms where we can grow more of our food.” Linked into a single entity (such as City Growers) with coordinated market operations and pooled resources, several quarter-acre micro-farms could have a significant impact.

Urban farming fits into a broader vision by Mayor Thomas M. Menino’s office that would ensure access to healthy, local, nutritious food at fair prices for all Bostonians. Encouraging food trucks, pushing for the development of a public market, and even supplying vouchers for low-income residents to use at farmers’ markets have been part of that vision. Through the Mayor’s Office of Food Initiatives, the city hopes to foster a broad spectrum of agricultural activity that ranges from rooftop growing to aquaponds to service companies for a new agricultural sector.

The economic stakes are surprising. At a City Hall agri-economic powwow in November, Trish Karter (founder of Dancing Deer Baking Co. and now of LightEffect Farms, which proposes farming in rooftop greenhouses) estimated that the packaged salad greens market in Metro Boston is worth $100 million annually. A lot of growers would like a piece of that.

Most significantly for potential dirt farmers, the Boston Redevelopment Authority is taking an inventory of vacant land in the city to determine what might be suitable for agriculture. Part of the task involves determining the actual owners of the parcels — many are in city hands, and many others fall under the aegis of the Massachusetts Department of Conservation and Recreation or even the MBTA. Still more are privately owned.

In a pilot project, the city created an urban agriculture overlay district on two city-owned plots in Dorchester. Through Victory Programs, women and children in a homeless shelter garden one plot to supply their kitchen. The other plot has been transformed into productive farmland by City Growers.

Plot-by-plot overlays are a cumbersome way to grant permits for urban farming. A year ago, the city began crafting changes in the zoning code to allow “a spectrum of urban agricultural activities” without variances. Final Draft Article 89 will be presented in neighborhood meetings across the spring and in public hearings before the Zoning Board in the summer.

It’s a process being followed closely by the Urban Farming Institute, the third co-sponsor of the Urban Farming Conference. Established last summer as a not-for-profit to support the development of urban farming in Boston, UFI has about 25 volunteers on its board of directors and working committees. Among them is the godfather of community development and neighborhood-centered urban land use, Mel King. Lloyd and Connors of City Growers were among the founders of UFI and remain actively involved.

Besides serving as an advocate for urban farms in policy discussions, UFI’s principal tasks are to incubate farms and incubate farmers. “For now we are looking to use city land,” says Dave Madan, a UFI founding board member and executive director of theMove, a Cambridge-based group that organizes educational farm volunteer workdays. He serves on UFI’s land-use committee. “In the future we will be looking at options to actually acquire land or look at long-term leases.”

More immediately, UFI has been recruiting about a dozen would-be urban farmers for a 28- to 30-week training program that begins with classroom sessions, followed by practical experience in the field. “The big vision,” says Lloyd, a UFI board member, “is that when they are done, each one gets a plot of land to grow on.”