Unearthing Urban Rooftop Farming

After a day filled with blistering heat, Mary Ostafi, Executive Director & FOOD ROOF Facilitator, sits down with me for a chat about rooftop farming. Ostafi has been cultivating the FOOD ROOF Farm, located in Saint Louis, Missouri, for three years and has been elated at the growing success and support they’ve received. She was kind enough to take time out of her schedule to explain rooftop farming and the rise of urban agriculture, a relatively new way to bridge cities and organic-based food systems.
When I initially thought of a rooftop farm I envisioned a few pots with the casual tomato and pepper plant. However, this is nowhere near the scale of the modern day urban farm.
There are different variations for rooftop gardens across the country, but Ostafi introduced me to the most prevalent: rooftop soil farms, hydroponic greenhouse farms, aeroponic farms, and raised bed / container gardens. It’s important to familiarize yourself with these different models as it can help determine which farm would be a good fit for you.
Rooftop Soil Farms: These farms utilize a green roof system. Ostafi describes it as several layers of material, which end up being about four inches thick. They consist of a root barrier that keeps the roots from reaching the rooftop and causing leaks. Then there is a second layer that uses separation fabric followed by a  water retention board that hold excess water after rainstorms. Lastly, a thin layer of fabric is installed to keep the soil from penetrating into the layer below.
Essentially a rooftop farm mimics a typical garden you’d have only it’s located on top of a structure. Successful examples are the FOOD ROOF Farm and Brooklyn Grange whose total rooftop farm space ranges from 10,000 to 108,000 square feet. Both farms practice organic commercial urban farming.
Hydroponic Greenhouse Farms:  Greenhouses were originally designed so that the farmer has complete control of the growing environment. This ranges from nutrition that the plants receive to the CO2 levels.
Hydroponics is the practice of growing plants using liquid nutrient solutions eliminating the need for soil. A prime example is Gotham Greens, who’s first farm in Greenpoint, Brooklyn  was the first commercial-scale rooftop greenhouse in the United States.
Gotham Greens now owns and operates four greenhouse farms totaling over 170,000 square feet in New York and Chicago. Their second greenhouse is located on top of Whole Food Market’s flagship Brooklyn store and is the first example of a commercial scale greenhouse implemented into a supermarket. Their third farm is a 60,000 square foot rooftop greenhouse in Jamaica, Queens and the fourth is a 75,000 square foot rooftop greenhouse on top of the new Method factory in Pullman, Chicago. Their Chicago greenhouse is set to produce over 1 million pounds of fresh produce per year for the local Chicago market and is considered “The World’s Largest Rooftop Farm.”
Aeroponic Farms: Aeroponics is a growth system where plants have the potential to grow vertically. This specifically appeals to farmers who have limited space. Aeroponics and hydroponics are both grown in a nutrient solution, but while hydroponics is grown in a constant stream of water, aeroponics is on a timer.
Raised Beds: These are typically the most economically feasible gardens to create. They’re a stand-alone structure for soil and plants, but the downfall with them is they are not the most efficient. Some planter boxes are on casters, which can be easily rearranged if needed. Uncommon Ground, an eatery in Chicago with an emphasis on the organic, has utilized the beauty that rooftop farms can afford.
They employ planter boxes and earth boxes, which provides them with over 1,000 pounds of produce from their 700 square foot growing space. Placing great importance on seasonal, regional, and organic ingredients this could only have been made possible by utilizing their rooftop. They’re famous for being the “1st Certified Organic Roof Top Farm in the US” and have now clinched the title for “The 1st Certified Organic Brewery in Illinois.” With two local locations, this restaurant is setting the precedent for organic gardening within restaurant quarters.
Normally, farmers focus on one method, but in Ostafi’s case she decided to take a different slant by experimenting with several types of farming styles to find one that’s most suitable for STL.
“We’re trying to figure out the microclimate here and what’s the most successful [for providing results]. Essentially what we have here is a living laboratory of a green space. This is crucial when people begin experimenting in rooftop farming because climates are so variant and what works for one city’s farmers may release opposite results in another.”
Urban agriculture is a rising trend with tangible economic and ecological benefits.
Some experts say 40-50% of energy costs are reduced when a green roof system is used. The layers, and especially the soil, act as an insulator keeping the cool air in during the summer and out during the winter. Another perk is the automatic protection the roof membrane receives. No hail damage or wind damage can occur, increasing its lifespan.
From an ecological standpoint, the organisms that are being produced are able to utilize many components found in the outside environment. The FOOD ROOF Farm and other green roof systems collect water within a retention board that has been designed underneath the soil. The FOOD ROOF Farm serves as a perfect example to the benefits of a retention board. Collecting up to 17,000 gallons of water per storm this life source is readily available for plant roots to wick up through capillary action. In other situations, such as a greenhouse, cisterns are relied upon where water is collected and then used to water the greenhouse.
But what’s one natural energy resource that’s not dispersed? Heat. Across the nation, urban heat islands have been destabilizing the already precariously balanced climate. With the mix of concrete and black rooftops, heat is collected and increases in temperature as the day progresses. Once nightfall hits the heat continues to radiate increasing the surrounding temperature. This is why cities are typically warmer, even if it’s a few degrees, than rural areas.
Not only is urban heating uncomfortable, but it’s causing tangible problems, such as increased chances of extreme weather patterns. Due to our energy outputs, we’re changing natural weather patterns in our cities setting up perfect conditions for tornados and other natural disasters. When soil covers the rooftops it decreases the urban heating therefore stabilizing the environment to a relatively normal temperature.
Urban agriculture is slowly gaining popularity, and Ostafi is witnessing this firsthand through direct conversations from other farmers.
“Now people are coming to us with interest. Our motto is build it, and they will come. Our focus is building rooftop farms in STL, but our reach goes everywhere. There aren’t a lot of people who have expertise in this area. We are providing consulting services for future rooftop farmers and presenting our knowledge at urban agriculture forums and industry trade shows.”
Commercial sized rooftop farms are maybe a dozen with no specific coalition. Urban farms are starting off small, but with enough hands you too can be involved in building something beautiful. Not only will people in your community enjoy the fruits of your labor, but you’ll be surprised just how many people are eager to become involved.