Green Roof Trials
In May 2015 we finished construction on our green roof trial gardens. The goal of the research is to expand current green roof plant palettes for warmer zones of the southeast, including zones 8 and 9. Most of the initial green roof plants were adapted from other areas of the country with a more established industry, such as the Midwest and Northeast. Here, plants that perform well further north might not fare as well in our heat and humidity. We aspire not only to increase the palette, but also to increase creativity in design aesthetics—we feel the best roofs are varied in texture and contrast, with natives and exotics colliding in explosive displays.
Our green roof trial structures are designed to imitate an actual green roof without unnecessary expenditure on infrastructure required of a habitable building. They are smaller scale green roof platforms elevated about 4’ off the ground. Twelve structures measuring 10’ by 15’ were constructed out of wood and comprise all typical layers of a standard green roof. Six structures have 4” of growing media while the other six have 6” of growing media (Erth-HydRocks Semi-intensive Green Roof Mix). These 2 growing media depths represent common depths found on green roofs. All structures were planted with the exact same number and species of plants to allow for replication.
Each structure is irrigated with overhead irrigation. Since we are testing plant performance we want to ensure all plants receive uniform irrigation, so four pop-up sprinklers are on the corners of each structure. During the warm season irrigation runs for 4 minutes per day on each structure.
We continuously monitor growing media temperature and moisture with soil sensors (Irrometer Co.). Both our maintenance facility green roof and green roof trial gardens are equipped with the same system. It will give us a comparison of how the green roof trial garden growing media is behaving in comparison to the actual maintenance facility green roof. We plan to mimic common industry practices for irrigation amount and frequency so that our research translates well to the industry and practical use. It is safe to say that many plants will perish during the trial but that is expected from plant trials. We plan to run the trial for at least 2 years before we make conclusions about plant performance.
For more information, photos, and video of our green roof trial gardens visit link: http://moorefarmsbg.org/green-roof-trial-garden/