Julianna Razryadov’s passion for green roofs has led her around the world and back again. After traveling to Switzerland, New Zealand and Malaysia, Razryadov, who grew up in New York City, returned to the Northeast to study the benefits of using native plants to boost the sustainability and aesthetics of green roofs across the United States.

She began her exploration at Penn State.

Along with a team from the Center for Green Roof Research, Office of Physical Plant (OPP), Student Affairs, and Development and Alumni Relations, Razryadov — who is a graduate student in horticulture — helped with the establishment of a new green roof at the HUB-Robeson Center. A gift from the Class of 2014 and constructed as part of the HUB addition and renovation project, the rooftop opened this summer as a space for Penn Staters to relax and enjoy nature from the center of campus.

Razryadov took on an advising role in the project, helping to select plants, create educational signage, develop watering schedules and more. For her own research project (and with the support of the class gift), she planted an experimental garden alongside the larger swath of succulents on the roof and used a digital weather station to track data about humidity, rainfall, water retention and soil temperatures.

“While green roofs have been used around the world throughout history, contemporary green roofs are still relatively new in the United States and there’s so much to learn,” said Razryadov, who is also a member of Penn State’s Student Farm. “The technology we’re using has been very helpful in collecting and tracking data about the health of the plants I’m growing.”

Green roofs — which are comprised of an as-light-as-possible layer of vegetation and a growing medium such as soil — are prized not only for their aesthetic appeal, but for the sustainability benefits they provide.

Like the green roofs atop the Millennium Science Complex, Lewis Katz Building, Forest Resources Building and the Student Health Center at Penn State University Park, the HUB’s reduces stormwater runoff to nearby waterways, acts as a natural form of insulation to reduce indoor energy use, improves air quality and enhances biodiversity by providing a habitat for birds and insects.

“To reap these environmental benefits and protect the investment of installing a green roof, plants must be low-maintenance and able to withstand shallow soil depth and harsh environmental conditions from year to year,” said Chad Spackman, a facilities project manager in OPP who oversaw the project design and construction for the recent HUB addition and renovation. “To avoid using plants that require frequent watering, we chose sedum, a variety of hardy succulent, for the largest portion of the HUB green roof because of its ability to survive in hot, cold and drought-like conditions.”

But Razryadov says she is curious about injecting more diversity and wildness into these often standardized spaces. She believes native plants, which might or might not be drought tolerant, could also survive in these rooftop gardens.

“I think within the green roof community there is a tendency to simplify and stick with plants that have proven successful in the past, in part because they align with building and stormwater runoff regulations,” Razryadov said. “I believe local climates and weather patterns should also influence how we engineer these spaces, so we can begin to use more native species that grow naturally in a particular region and are also beneficial to local birds and pollinating insects.”

To diversify her small rooftop garden patch, she eschewed sedum for mountain mint, evening primrose, bee balm, blanket flower, wild strawberries and prairie Junegrass — all plants that grow throughout the Northeast and that up until now haven’t been widely cultivated or tested on green roofs.

She turned to the HUB’s rooftop weather station — which is available as an educational tool for students and the wider Penn State community — to track the relationship between her plants’ health and longevity and rooftop environmental conditions over the course of the summer.

When designing the roof, Spackman says it was important to include a method for collecting and quantifying data about the performance of the roof to use for education and outreach, but that at the same time wouldn’t use much energy in the process.

“The weather station we developed is a renewable system that powers itself through a photovoltaic solar panel that connects to a rain gauge, soil moisture sensor, weather sensor and infrared radiometer, each of which monitor a particular piece of weather data,” Spackman said. “The instruments then transmit information to a data logger to calculate, store and send to Razryadov and the Center for Green Roof Research for analysis and sharing.”  

Razryadov says the data from the weather station was an invaluable resource in better understanding the reasons the native plants in her garden survived through the summer.

“I’ve found that below-ground interactions among plant roots have a lot more to do with above-ground growth than we give them credit for. Combining plants with different kinds of root architecture creates a more sustainable green roof system in terms of water use, habitat and also just plain survivability,” she said. “I spent a lot of time up on that roof and I learned a lot about how to continue to pursue these questions I have.”

Razryadov says her curiosity coupled with the opportunity to educate people are what motivate her.

“Alpine environments are some of the most diverse of any around the world — you can see 20 plant species in one tiny area,” she said. “If we can continue to tap into this diversity, I believe the green roof industry would benefit and the public would be able to discover and enjoy the variety of beautiful, wild plants in their own backyards. There is so much potential and room for creativity in this space and it’s really exciting to be a part of.”