Some produce marketers apply the term “local” to product grown more than one hundred miles away, possibly in another state, from the stores where it’s being sold.

BrightFarms LLC, New York, has a different idea.

“We call this ultra-local,” chief executive officer Paul Lightfoot said.

Bright Farms spent the past four years serving as a consulting firm, helping schools, a commercial greenhouse company and others — including a Whole Foods store in New Jersey — build hydroponic greenhouses on the roofs of buildings.

This year, the company has changed its business model and will design, finance and build greenhouses that it will operate on retailers’ roofs. The company then will sell its products — including hydroponic lettuce, greens and tomatoes — directly to the stores below.

Lightfoot said BrightFarms plans to hire local growers on a contract basis to work the rooftop operations, and the company will pay the growers a percentage of its sales to retailers.

The growers can “focus on growing food without worrying about sales and marketing and raising capital,” Lightfoot said.

The company has named Chad Brian its master grower. Brian, who will be responsible for working with growers in each location, is a veteran of the Ontario greenhouse industry, having worked for Mastronardi Produce and Domric International for more than a dozen years.

BrightFarms is in the process of designing greenhouses for four different retailers.

“Everybody wants to start with one,” Lightfoot said.

He declined to name the retailers or the greenhouse locations. However, the company is steering clear of large West Coast growing areas such as Salinas, Calif., and Yuma, Ariz., he said. Instead, it is focusing on areas where the concept might benefit retailers the most, including the East Coast, Midwest, New England and Mid-Atlantic regions.

Lightfoot said the first four greenhouses should be under construction by the third quarter and could be operational by early next year.

The rooftop greenhouses can be included in the design of new retail stores, he said, but retrofitting older stores also is possible, depending on their structural capacity.

A new 50,000-square-foot retail store could be built with a 43,000-square-foot greenhouse on the roof, Lightfoot said. A greenhouse retrofitted on the roof of a similar-sized existing store would use a lower percentage of the roof’s surface.

Lightfoot estimated that a 40,000-foot greenhouse could yield 500,000 pounds of produce per year. That projects to $1.25 million to $1.5 million in sales for BrightFarms to the retailer.

That likely is too much volume for a store that size, and BrightFarms is looking to work with retailers who operate multiple stores in a given area.

“We like the cluster model,” he said.

Lightfoot said product likely would be packed on the roof, and a conveyor would be used to move it to the ground level.

The business model will result in better produce, better products and do it in a fashion that is better for the environment than any other growing method, he said.

“It hasn’t spent a week on a truck, so it’s going to be more attractive,” he said. “It’s going to be more fresh, and it’s going to last longer. There will be less shrink. The retailer is going to sell a higher percentage of what they buy.”

BrightFarms also is offering its retail partners long-term discounts by way of fixed prices, which are guaranteed to adjust only by the Consumer Price Index.

“We’re insulated from commodity inflation because there is no oil in our supply chain,” Lightfoot said. “We’re eliminating volatility in the marketplace.”

Participating retailers also could be immune from the potentially devastating effects of product recalls during foodborne illness outbreaks, Lightfoot said, because customers will know where their produce is coming from.

“If something like the 2006 spinach recall happens again, you still have regular volume and your customers will trust you in a way they don’t trust other stores,” he said.

BrightFarms offers some of the same environmental benefits as other greenhouses — no tractors, no oil-based fertilizer, water conservation, and no chemical pesticides — with the added benefit of no long-haul trucks, Lightfoot said.

“Some retailers we’re working with are focused on the economics of it, but when you talk to the merchandisers involved, you can see them get dreamy-eyed about this,” Lightfoot said. “It’s the most local produce there is.”