January 30, 2013 | Jan Fletcher

Traveling from farm to market has never been a shorter trip than it is for the produce grown by Green Sky Growers, a rooftop aquaponic farm, in Winter Gardens, Fla. The farm’s main client is a restaurateur housed in the same building. Delivering fresh produce is a mere one-minute commute in an elevator.

The unique aquaponic operation arose through the personal vision of Bert Roper, an aquaculture expert from Winter Gardens, Fla., whose ancestors settled the area more than a century ago. Although Roper passed away in late 2012, his legacy lives on. It’s visible in the lush, edible greenery that draws nutrients from a rooftop pond atop a multi-rise, 3,000 sq. ft. warehouse. The indoor aquaponics operation produces both tilipia fish and edible plants, which are cultivated in tandem, forming a closed ecosystem. Ryan Chatterson, facility supervisor for the farm, says all waste generated by the fish is recycled, via natural methods of decomposition.

The remainder of the produce is sold to a restaurant situated across the street. “We have pretty much zero miles from farm to plate,” Chatterson says. “We are producing a premium product for a premium market, and I’m not trying to fit with the guy selling 50-cent heads of lettuces from California.”

The farm produces several varieties of lettuce and herbs, including rosemary and cilantro, as well as vine crops – cucumbers, squash, heirloom tomatoes, bell peppers and specialty items. Since the operation is located within a subtropical zone, year-round crops flourish.

The normal season for growing lettuce ends in spring in Florida, he says. In the hottest months he plants a denser crop, which is harvested early. “I can offer lettuce year-round in the same space and make money.”

Chatterson works closely with the restaurant owners, and plants according to a schedule that best suits the needs of the restaurateur. The produce is sold to four nearby restaurants, a local co-op, and a farmer’s market. He turns down around six restaurants a month. “They call us looking for produce, but we don’t have enough. It’s nice to be on the other side. We’re not having to market the business, it markets itself.”

The building housing this aquaponic rooftop farm was constructed specifically for that purpose, he says, and he estimates the demonstration project ran over a million dollars. To replicate a similar setup, and expect it to yield a profit is a big stretch, he admits. Yet, Chatterson says the vision is what drives the project, not bean counters. Pentair, a global player involved in water, fluid, thermal management, and equipment protection, bought the operation from Roper, Chatterson says.

Roper was well known as a generous philanthropist, who dreamed of replicating the operation worldwide, using existing infrastructure whenever possible, Chatterson says. “We don’t just plant the crops that are going to make us the most money,” he says. “We do a wide variety of crops.”

Although it’s difficult to quantify the costs of replicating the aquaponic operation, he estimates that growing a crop of basil and bib lettuce – high dollar crops – could potentially yield sales of around $100,000 a year.

Going farm to market via an elevator shaft, or a next-door neighborhood farmer’s market, virtually eliminates transportation costs, he says.

A rooftop garden isn’t a common model for aquaponics, but the Green Sky Growers project served as a valuable demonstration model of what is possible in urban farming, he says. Chatterson notes a similar operation could be situated atop any surface structure capable of supporting the weight of the water required for the operation. A parking lot would work, he says.

The heart of the operation is the symbiotic relationship between the tilapia, which have been called the “perfect factory fish,” and the crops. Although some environmentalists have raised alarms over tilapia fish farming methods, as tilapia are considered an invasive species, that’s simply not an issue in a closed ecosystem.

“In a lake you have fish, the fish are going to be eating, they excrete waste and then you’ve got lake brush, you’ve got lily pads – things like that are going to grow off of those nutrients they put into the water,” Chatterson says. “This is the same idea, except it’s engineered so you can grow edible plants instead of lake weeds.”

“We’re basically going from fish to solid waste, turning that more into a liquid nutrient by dissolving that waste in the water, and that’s what the plants are picking up,” he says.

The urban aqua farm is easy to replicate, he says. A mothballed parking lot could fit the bill, he says. “I taught my Mom how to do it over the phone and she lives in Ohio,” he says. “I can put this thing in my house and bring everybody over, and have a hundred different varieties growing — all looking premium. It’s really beneficial in that aspect – you can do it anywhere.”