Students successfully grew eight varieties of vegetables on the roof of Texas A&M’s Langford A building during the 2014-15 academic year, advancing findings in an ongoing green roof research project led by Bruce Dvorak, associate professor of landscape architecture.
“We learned that leafy greens and herbs are definitely viable for green roof production,” said Dvorak. “Kale, lettuce, and parsley were the most productive.”
Dvorak’s students, working with faculty and students in the departments of horticultural sciences and metrological sciences, have successfully grown more than 50 plants and vegetables since the project, funded by a university Tier One Program grant, began in 2012.
Green roofs promise many benefits, including lowering a building’s energy use, cleansing stormwater and improving air quality, as well as providing aesthetic benefits and higher property values and habitat for some urban wildlife such as hummingbirds.
The green roof phenomenon is also expanding to include food crops, because land development and urban population growth are creating opportunities for new markets, said Dvorak.
“In cities such as Chicago, Boston and New York, restaurants are serving produce grown on rooftops,” he said.
Students tried growing 34 varieties of food crops in 2014-15, and found that arugula, chives, cilantro, mints, shallots, strawberry, lettuce, kale and thyme had the highest survival rates.
In addition to produce, said Dvorak, students populated the roof’s living walls with plants that don’t mind having roots in wet soils such as Scotch moss and Mexican petunia. “The microclimate on the living walls creates a moist habitat,” he said.
The project has been revealing which plants will succeed in a roof bed or living wall design when combined with a particular irrigation system.
Determining what kinds of plants will survive is a slow process, he said. “In a region with weather like Texas, setbacks should be expected. It’s going to take time to learn what works.”
"There's no book titled 'Green Roof Species for Texas,'" he added, glancing at a bookshelf in his office. We're writing the book right now by finding out what will grow and what won't."
Public interest in green roofs and green walls is rising, said Dvorak, resulting in a growing market and new job opportunities. Kirk Laminack, a graduate student in the Department of Horticultural Sciences who graduated in 2014 and had been with Dvorak’s project since its inception, was hired by a botanical garden in North Carolina to a fulltime green roof and green wall systems position.
“People are really interested,” said Dvorak. “The question is how do you do it?”