Some studies have found that many native species do not survive on green roofs without irrigation (Monterusso et. However, anecdotal observations in Minnesota, Michigan, Chicago IL and Lincoln NE, suggest that deep rooted native prairie species grow their roots horizontally on green roofs (Kestrel Design Group (2013), Sutton (2011), Grese (2008)). The shallow growing medium of green roofs does not allow for such deep root growth. Use of native prairie species on green roofs is controversial because most prairie species survive droughts by sending roots very deep into the soil to access water. Plants growing in bedrock bluff prairies are adapted to growing conditions very similar to those found on many green roofs, including thin growing medium and high exposure to wind, sun and drought. Bedrock bluff prairies have thin soil layers over bedrock and are often found along river bluffs. Many species found in Minnesota’s bedrock bluff prairies have also been found to grow well on Minnesota’s green roofs. Image Courtesy of The Kestrel Design Group, Inc. Native Plants on Phillips Eco-Enterprise Green Roof. Many other Sedum species can also perform well. The list below shows some of the most common species. Note: Many species of sedums grow well on green roofs in Minnesota. Non-native succulent species appropriate for extensive green roofs in Minnesota. Salt tolerance of common green roof and green wall plants. Landscape and Urban Planning (Elsevier) 104:310-319. Effect of green roof media depth on Crassulacean plant succession over seven years. Sedum cools soil and can improve neighboring plant performance during water deficit on a green roof. Other studies of succulents on Midwestern extensive green roofs that are not included in the Dvorak and Volder (2010) review include Timber Press.ĭvorak and Volder (2010) summarized North American green roof vegetation studies, including studies on growth of succulent plants on Midwestern green roofs. Green Roof Plants: A Resource and Planting Guide. Michigan State University Extension Bulletin E-3047. Selecting Plants for Extensive Green Roofs in the United States. Longer lists of succulents available for green roofs, are available, for example, in A few of the hardiest sedum species for Minnesota are listed below, but these are only a very small portion of the huge palette of Sedums available on the market. For example, Durhman et al (2006) found some Sedum species could survive and maintain active photosynthetic metabolism even after 4 months without water. Sedums and other succulent plants are often used on green roofs because they are tolerant of the dry conditions found on most roofs. Photo of sedums on the Target Center Arena green roof in Minneapolis, MN. The section on design criteria for green roofs provides guidance on factors that affect green roof plant selection. While a considerable number of green roofs have been installed in the Twin Cities area, few green roofs have been installed to date in more northern parts of Minnesota that have a harsh climate that will be challenging for green roof vegetation. Many of these green roof species have not yet been tested in all of Minnesota. Suitability can vary with climate, microclimate, project goals, and maintenance budget. Species included on the plant lists below may not be appropriate for all projects. While most of the first extensive green roofs in the US were planted with non-native succulent species, mostly Sedum species, the plant palette for green roofs in the United States, and in Minnesota, is rapidly expanding to include many herbaceous plants and grasses. The plant list discussions below pertain to extensive green roofs. Given adequate growing medium depth and irrigation, just about any plants, even trees, can be grown on green roofs. Green roofs create green space for public benefit, energy efficiency, and stormwater retention/ detention. Green Infrastructure: Green roofs consist of a series of layers that create an environment suitable for plant growth without damaging the underlying roof system.
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