Take a Peek Inside the World’s Largest Rooftop Greenhouse

Clocking in at 75,000 square feet, the world's largest rooftop greenhouse is situated on top of the Method soap factory in Chicago's Pullman neighborhood. This greenhouse, built and operated by Gotham Greens, is two acres and produces the same crop yield as a 50-acre farm. 

"Chicago has a really great food scene and has been a real leader in urban farming," Nicole Baum, marketing and partnerships manager for Gotham Greens, told weather.com. Prior to opening its Chicago greenhouse, Gotham Greens had only operated rooftop greenhouses in New York City.

Gotham Greens was established because "we realized that a lot of lettuces and basils in the market are coming from places like California and Mexico and Israel," Baum said. "We just realized that there had to be a better, more sustainable way to get the product and deliver a freshly harvested basil plant rather than something that had traveled across the country and was a week old before it got to our market."

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In the years since, Gotham Greens has expanded to four rooftop greenhouses, including the Chicago greenhouse, which opened in November 2015. Thanks to the company's use of renewable energy and a hydroponic growing system that doesn't use soil, they are harvesting every day and delivering their lettuce and basil products to local grocers and restaurants fresh. 

The company's mission is tied to their belief that the current food production system is inefficient. "We realized that there was an opportunity to grow and produce a fresher product on our own terms," Baum said.

In the case of the Chicago greenhouse, the opportunity to use the space came as Method was building a LEED-certified factory with a green roof. Since both companies are sustainability leaders in their own sectors, the project made sense. 

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The hydroponic growing system is what Gotham Greens uses in each of its greenhouses foregoes soil and instead dissolves all the nutrients the plants need into water and then recycling it. This system means that the rooftop greenhouses are using one tenth the water of a traditional farm and developing a cleaner product as the hydroponic system helps eliminate water pollution that would come from fertilizers. To top it all off, the system is incredibly productive. "We're getting 25 times that of a traditional soil-based farm," Baum said.

To maintain the sustainable urban farms, the four greenhouses all use solar and wind energy, as well as some paid renewable energy, to power production. The greenhouses are also completely climate controlled, which ensures a consistent product. Baum said that each greenhouse has sensors that constantly measure light levels, humidity, carbon dioxide and temperature.

"We’ve programmed the greenhouse to automatically turn things on and off depending on what those sensors are reading," Baum said. "If the sensor is saying it’s a hot summer day and it’s 90 degrees in the greenhouse, then the roof will open up and the windows will open and we have fans and misters in place that will cool down the greenhouse.

"We also have large shade curtains that will open up and shade our plants if there’s too much sunlight. There’s a really incredible suite of technology that we have customized that allows us to have very consistent yields of high-quality products year-round."