A massive former factory roof in Berlin will become a farm to produce food for local residents and could be a model for future city farms, its planners say.

The Fresh from the Roof project is intended to create a 75,000-square-foot roof garden, complete with a fish farm, to provide Berliners with locally grown food, Der Spiegel reported Monday.

Traditional farming needs to evolve, the project's founders said, and urban farming needs to lead the way.

"Humankind is driving fast into a wall," Fresh from the Roof co-founder Nicolas Leschk said. "Global resources are running out. With so many people living in cities, we need to think locally."

The roof of the former malt factory in Berlin's Schoneberg district should begin to yield lettuce, herbs and tomatoes as well as different species of fish by 2013, he said.

The project's founders say it will cost about $6.7 million to set up the roof farm and are looking for investors.

"This is a gap in the market and we want to close it," co-founder Christian Echternacht said.