One of the fastest growing areas of landscaping in America has been what we call the ‘functional’ applications of native plants. Whether it’s streambank restoration, rain gardens or habitat reconstruction, North American native flora now have a whole new purpose besides the fact that they are attractive, durable plants.
Today architects and developers are increasingly turning to planted rooftops as a viable and attractive alternative to ordinary gravel-and-tar commercial installations. There are significant practical, economic, environmental and quality-of-life benefits to a green roof:
- Stormwater retention. Green roofs assimilate large amounts of rainwater rather than channeling it into the municipal stormwater system resulting in overloads.
- Heat island effect. A green roof affects not just the building it crowns but the entire neighborhood, thanks to the evaporative (release of water by the plants) cooling it generates that counteracts the heat buildup inherent in concrete and asphalt urban environments. With most HVAC units placed on top of buildings, this cooling, as much as 20-30 degrees results in operational savings.
- Urban wildlife habitat. Green roofs are most commonly found in cities, and provide resting and feeding stops for wildlife, particularly small birds and butterflies.
- Insulation properties, both hot and cold. The soil and vegetative matter of a green roof buffers the cold of winter winds and cools the thermal load delivered by the summer sun, moderating the heating and cooling needs of the building below.
- Urban garden. An urban green roof is often the only “backyard” (or ‘topyard’) an apartment or condo dweller has. An attractive alternative to traditional roofs that help to enhance urban quality of life.
- Pollution. Green roofs absorb air pollution, water pollution, and carbon dioxide while producing oxygen.
- Noise reduction. Green roofs buffer sound reducing noise levels.
- Extended roof life. Plants and soil protect underlying roof material by eliminating UV exposure
There are two types of green roofs: intensive that utilize 6″ to 2 feet of soil mix allowing for a variety of plant material from perennials to trees; and extensive whose soil depth is 4″ to 6″ limiting the choice of plants. Many native plants are suitable for green roof use. In particular, we have found that cedar glade plants, common in middle Tennessee, are tailor-made for Green roofs. A cedar glade is wet, cold and exposed in winter and hot, dry and exposed in summer, just like a rooftop. GroWild, Inc. has designed and installed successful green roofs using natives exclusively with excellent results.