The roof at my workplace is a 1-2% slant for drainage and has the right growing medium to support drought resistant succulent plants like sedum. Stonecrop (Sedum spathulifolium) is the primary planting but we also have Butterfly weed (A. tuberosa) thriving in the full-sun space. The plants remove air particulates, produce oxygen and provide shade.
Rain water that percolates through the soil layer drains into a rain garden and into rain barrels that hold water to minimize flooding and stress on sewage systems. The “living roof” helps beat the heat, keeping the building interior cooler and returning moisture to the air through evapotranspiration thus reducing our electric bill. Green roofs also provide benefit over dark, solid surfaces that create an “urban heat island” effect that raises air conditioning demands and air and sound pollution levels.
The roof also has solar panels to support our electric needs and has at times been home to a weather station, beehives and a culinary corner with space for a few herbs.
David Alexander is author of the Buzz Into Action & Hop Into Action Science Curricula. He specializes in making nature accessible to people and wildlife. You can follow him at www.natureintoaction.com