I recently visited Brooklyn Grange, a rooftop farm operating in Brooklyn and Queens, while reporting an article on farm tech. The farm started in 2010 and the farmers say they are now producing 40,000 pounds of produce per year. The farm is also profitable, which I found impressive considering the overhead costs the farm must be facing in such densely-populated areas.
The greenhouse the group recently installed is especially interesting; it was custom designed to conform to New York City building codes, which required double the amount of steel normally found in the structures, according to Ben Flanner, the farm's head farmer. Designed by Greg Garbos of Four Season Tools, the high tunnel, as it is more accurately known, extends the growing season for the farm with a structure that traps solar heat and can be cooled through panels that open and shut.
"A high tunnel will move your hardiness zone about one and a half zones to the South, or about 500 miles," Garbos, an engineer who also owns City Bitty Farm in Kansas City, told me.
As Flanner and Garbos pointed out, the high tunnels are not meant to radically change seasonal growing. " We're not trying to shatter the climate—it's not about growing mangoes in January," Garbos said. But it will help give Brooklyn Grange an advantage. Their high tunnel will serve as a propagation house in the spring and allow the farm to jumpstart their growing season, probably by about three to five weeks.