The crumbling old greenhouses on Woolsey Street in San Francisco’s Portola District were once the center of the neighborhood’s thriving flower-growing industry.

The nurseries are now at the heart of a development battle over 63 homes. A community group wants to transform the site into an urban farm, but a developer has been working to build apartments there since 2017.

Now, a supervisor is trying to landmark the site to help preserve it. But Supervisor Hillary Ronen, who’s proposing the landmarking, says she’d like to see both housing and farming on the 2.2-acre tract — if the developer and neighbors can make a deal.

Ronen’s legislation, which she’ll introduce Tuesday, initiates a landmarking process that would require the support of the Board of Supervisors. It comes as developer L37 is working on a plan at 770 Woolsey St., an entire city block home to 18 greenhouses that for 70 years supplied cut flowers to florists throughout the city.

While the block was one of about 20 cut-flower growing operations in the neighborhood, most of the greenhouses were torn down and the land redeveloped into row houses in the early 1960s. The last of the greenhouses shut down in 1990.

Honoring the history of the greenhouses with a contemporary twist on urban farming has become a passionate cause for many residents in the Portola, which in 2016 the city officially designated the Garden District. A community organization, the Friends of 770 Woolsey, commissioned a study of various approaches to creating an urban farm on the property.

Though designating the property as a landmark will make it more difficult to develop, it doesn’t mean that all the decaying greenhouses must be preserved or rebuilt. Ronen said she supports a plan that both revives some of the historic use and allows some new residences.

“We can have it all,” she said. “I am pro building housing on the site and also in favor of preserving the rich history and legacy of the greenhouses and the flower-producing industry.”

So far talks between the community group and the property owners have not gone well. The developer offered to preserve about 20% of the site for farming, a deal that residents said was far from adequate. Neighbor Elisa Laird-Metke called what the property owner has offered “a glorified median strip on the edge of the property.”

“They haven’t compromised at all,” she said.

Eric Tao, a partner with L37, said he believes his group can find a middle ground with the neighbors.

“We believe strongly in preserving the rich history of the cut-flower industry of Portola, and believe this history can be celebrated together with building housing,” which is allowed on the site, said Tao in a statement.

The legislation comes nearly three months after the city’s Historic Preservation Commission, which advises the Planning Commission on preservation matters, voted to reject starting the process of landmarking the property. At the meeting, all commissioners said that staff for Mayor London Breed, who supports housing on the site, had called to encourage them to reject the landmarking.

Jeff Cretan, spokesman for Mayor Breed, acknowledged that “the mayor is supportive of housing in all our neighborhoods, including there.”

The commission’s decision defied the recommendation from planning staff to landmark the property. At the hearing, Commissioner Jonathan Pearlman said that landmarking the property would “suck the life out of the property in terms of future development.”

Laird-Metke said neighbors had no choice but to approach Ronen’s office after being rebuffed by the commission.

“We asked Ronen to step in because we didn’t get a fair shake at the Historic Preservation Commission,” she said.

Stacy Farr, who wrote the historic landmark nomination for the Friends of 770 Woolsey, said greenhouses tell the story of an industry that dominated the Portola neighborhood for decades. It represents an important legacy for the city’s Italian immigrant community, which dominated the industry, she added. It would be one of only a dozen landmarks in the southeast corner of the city — a fraction of the 273 landmarks citywide.

Farr said it “would be a big lift to rehab these greenhouses, but it is not out of the question.”

“In San Francisco we don’t just landmark pretty buildings. We landmark places that tell us about our whole history,” she said.

Though it’s unusual to landmark a property over the objections of the property owner, it’s not unprecedented. Both the Shriners Hospital in the Sunset District and the St. Brigid Roman Catholic Church on Van Ness Avenue were given landmark status despite opposition from the owners.

Neighbor David Gabriner said the greenhouse project is worthwhile.

“It is just a really good example of a neighborhood in San Francisco coalescing around something really positive,” he added.

The proposed landmarking was not well received by some housing advocates. Laura Foote, executive director of the pro-housing group YIMBY Action, called the legislation “outrageous.”

“This kind of deliberate attempt to thwart housing in a neighborhood that badly needs it is gross abuse of power,” she said. “Are we going to historically preserve every empty lot in San Francisco?”

Ronen said she is confident she can broker a deal with Tao, whom she called “a straight shooter and a kind and reasonable developer to deal with.”

“I feel very positive that we have the right people at the table to come up with something truly visionary,” she said.

J.K. Dineen is a San Francisco Chronicle staff writer. Email: jdineen@sfchronicle.com Twitter: @sfjkdineen