Given adequate growing medium depth and irrigation, just about any plants, even trees, can be grown on green roofs. The plant list discussions below pertain to extensive green roofs.
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.
Species included on the plant lists below may not be appropriate for all projects. Suitability can vary with climate, microclimate, project goals, and maintenance budget. Many of these green roof species have not yet been tested in all of Minnesota. 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. The section on design criteria for green roofs provides guidance on factors that affect green roof plant selection.
Sedums and other succulent plants are often used on green roofs because they are tolerant of the dry conditions found on most roofs. For example, Durhman et al (2006) found some Sedum species could survive and maintain active photosynthetic metabolism even after 4 months without water. 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. Longer lists of succulents available for green roofs, are available, for example, in
Dvorak and Volder (2010) summarized North American green roof vegetation studies, including studies on growth of succulent plants on Midwestern green roofs. Other studies of succulents on Midwestern extensive green roofs that are not included in the Dvorak and Volder (2010) review include
Non-native succulent species appropriate for extensive green roofs in Minnesota. Note: Many species of sedums grow well on green roofs in Minnesota. The list below shows some of the most common species. Many other Sedum species can also perform well.
Link to this table
|Scientific name||Common name||Plant height (inches)||Approximate bloom time||Flower color||Sun exposure||Winter interest|
|Allium schoenoprasum||Chives||10||Spring||White||Full sun to partial shade||Dormant|
|Sedum album||Stonecrop||6||Summer||White||Full sun||Red|
|Sedum hybridum 'Immergrünchen'||Stonecrop||6||Summer||Yellow||Full sun||Orange/bronze|
|Sedum kamtschaticum var. floriferum'Weihenstephaner Gold'||Russian Stonecrop||5||Summer||Yellow||Full sun||Red|
|Sedum kamtschaticum||Russian Stonecrop||6||Summer||Yellow||Full sun||Red|
|Sedum reflexum 'Blue Spruce'||Stonecrop||8||Summer||Yellow||Full sun||Blue-green|
|Sedum rupestre 'Angelina'||Golden Stonecrop||5||Summer||Yellow||Full sun||Coral/orange-red|
|Sedum sexangulare||Stonecrop||4||Summer||Yellow||Full sun to shade||Red|
|Sedum spurium 'Dragon's Blood'||Two Row Stonecrop||4||Summer||Red||Sun||Red|
Many species found in Minnesota’s bedrock bluff prairies have also been found to grow well on Minnesota’s green roofs. Bedrock bluff prairies have thin soil layers over bedrock and are often found along river bluffs. 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. 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. The shallow growing medium of green roofs does not allow for such deep root growth. 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)).
Some studies have found that many native species do not survive on green roofs without irrigation (Monterusso et. al. (2005)). However, in some projects, certain native species thrive on green roofs without irrigation or with minimal irrigation. Since irrigation is needed during the plant establishment period anyway, many green roofs include an automatic irrigation system to provide water in times of drought.
Native species have been planted on at least five extensive green roofs in the Twin Cities area built between 2005 and 2009. The following table lists some of the native species that have performed well on green roofs in Minnesota (Kestrel Design Group observations). Because all of these except for one are irrigated regularly, the ability of most of these species to survive without irrigation on extensive green roofs in Minnesota is not known. Species that have been found to survive with little or no irrigation in Minnesota or elsewhere in the Midwest are noted.
Native species that have been grown successfully on extensive green roofs in Minnesota
Link to this table
|Scientific name||Common name||Plant height (feet)||Approximate bloom time||Flower color||Sun exposure||Found to require irrigation in some projects or studies||Found to survive with little or no irrigation in some studies or projects|
|Allium cernuum||Nodding Wild Onion||1 to 1.5||July-August||Pink||Full sun to part shade||X3,4|
|Allium stellatum||Prairie Wild Onion||1 to 2||July-August||Pink||Full sun to part shade|
|Andropogon gerardii||Big Bluestem||2 to 6||n/a||n/a||Full sun to part shade||X1,2,*|
|Anemone patens||Pasque flower||0.5||April-May||Purple||Full Sun to Part Shade|
|Antennaria neglecta||Field pussytoes||0.5||April-June||White||Full Sun to Part Shade|
|Antennaria plantaginafolia||Pussytoes||1||April-June||White||Full sun to part shade|
|Aquilegia canadensis||Columbine||2 to 3||May-July||Red/Yellow||Full sun to part shade|
|Asclepias verticillata||Milkweed||1 to 1.5||June-August||White||Full sun to part shade|
|Aster ericoides||Heath aster||1 to 3||July-October||White||Full sun to part shade|
|Aster laevis||Smooth aster||1 to 3||August-October||Blue-violet||Full sun to part shade||X4|
|Aster lateriflorus||Calico aster||2||August-October||White||Full sun to part shade|
|Aster macrophyllus||Large-Leaved aster||1 to 2||August-October||Lilac||Full sun to part shade|
|Aster novae-angliae||New England Aster||3 to 5||August-October||Red-violet||Full sun to part shade|
|Aster oolentangiensis||Shyblue aster||3||August-October||Blue||Full sun to part shade|
|Aster sericeus||Silky aster||1||September-October||Purple||Full sun to part shade|
|Bouteloua curtipendula||Side-Oats Grama||1 to 3||n/a||n/a||Full sun||X1,*|
|Bouteloua gracilis||Blue Grama Harebell||0.5 to 1||n/a||n/a||Full sun||X1,5,*|
|Campanula rotundifolia||Harebell||1 to 1.5||June-September||Blue||Full sun to part shade|
|Carex pensylvanica||Pennsylvania sedge||0.5||n/a||n/a||Full sun to full shade|
|Carex vulpinoidea||Brown Fox Sedge||1 to 3||n/a||n/a||Full sun to part shade|
|Chamaecrista fasciculata||Partridge Pea||2 to 3||July-September||Yellow||Full sun to part shade|
|Coreopsis palmata||Bird's Foot Coreopsis||2||June-August||Yellow||Full sun to part shade|
|Dalea purpurea||Purple Prairie Clover||1 to 2||June-July||Yellow||Full sun||X4||X1|
|Fragaria vesca||Wild strawberry||0.5||May-June||White||Full sun to part shade|
|Fragaria virginiana||Wild strawberry||0.5||White||Full sun to part shade||X4||X1,*|
|Geranium maculatum||Wild geranium||1||April-June||Pink||Full sun to full shade|
|Geum triflorum||Prairie smoke||0.5||April-June||Red||Full sun to part shade||X1,*|
|Heuchera richardsonii||Alumroot||1||May-June||Greenish white||Full sun to full shade|
|Koeleria pyramidata||June grass||2||n/a||n/a||Full sun to part shade||X4||X1,2,3|
|Liatris aspera||Rough Blazing Star||1.5 to 4||August-September||Rose, lavender||Full sun to part shade||X4|
|Liatris cylindracea||Cylindric Blazing Star||1||July-October||Purple||Full sun to part shade|
|Penstemon grandiflorus||Large-Flowered Beard Tongue||2||May-June||Purple||Full sun to part shade|
|Phlox divaricata||Woodland Phlox||0.5 to 1.5||April-June||Blue||Part shade to full shade|
|Polemonium reptans||jacob's Ladder||1||April-June||Blue||Full sun to full shade|
|Ruellia humilis||Wild Petunia||1||June-August||Purple||Full sun|
|Schizachyrium scoparium||Little Bluestem||3||n/a||n/a||Full sun to part shade||X4|
|Solidago nemoralis||Gray Goldenrod||0.5 to 2||August-October||Yellow||Full sun|
|Solidago ptarmicoides||Upland White Aster||1||July-August||White||Full sun|
|Sporobolus heterolepis||Prairie Dropseed||2 to 4||n/a||n/a||Full sun to part shade||X4||X1|
|Thalictrum dioicum||Early Meadow-Rue||1 to 2||May||Greenish yellow||Full sun to part shade|
|Tradescantia bracteata||Bracted Spiderwort||1||May-July||Purple||Full sun|
|Tradescantia occidentalis||Western Spiderwort||2||May-July||Blue||Full sun|
|Tradescantia ohiensis||Ohio Spiderwort||3||May-July||Blue||Full sun to part shade||X3,4|
|Viola pedatifida||Bearded Birdfoot Violet||0.5||April-June||Purple||Full sun to part shade|
1Based on trial green roofs at Chicago Botanical Garden, Richard Hawke, Personal Communication
2Based on Kevin Carroll, personal communication, 2013.
3Based on research at Michigan State University, Rowe in Sutton et al 2012b
4Based on research at Michigan State University, Monterusso et al 2005. In this study, plants were irrigated the first growing season, and irrigation was then abruptly stopped July 10 of the second growing season, during an unusually warm and dry summer; plants were not irrigated at all during the third growing season.
5Based on observations at Phillips Eco-Enterprise green roof, The Kestrel Design Group personal communication, 2013.
*Goes dormant or turns brown with little or no irrigation in drought but rebounds when water is available again.
Many of the species listed in the above table, as well as many additional native species not listed, are also thriving on other Midwestern extensive green roofs, including, for example, Chicago City Hall (Dvorak and Carroll 2008, Carroll 2013), Chicago Botanic Gardens trial green roofs (Hawke 2013), and several other green roofs in Chicago, Toronto, and Lincoln NE. The Chicago City Hall green roof, installed in 2001, had 200 species as of 2012, most of which are natives. Its plants are grown in varying depths of soil (some extensive and some intensive), and regularly irrigated (Dvorak and Carroll, 2008). The Chicago Botanic Garden has 2 trial green roofs, installed in 2009, one of which is planted with natives. It includes planting depths of 4 inches, 6 inches and 8 inches of growing medium. Aiming to minimize green roof maintenance, the roofs have been watered only during extreme drought (beyond establishment), including once in 2011 and once in 2012 (Sutton et al 2012).
Not all the species listed in the above table are native in all parts of Minnesota. To find out in which parts of Minnesota these species are native, see Plant species range maps from the Minnesota Department of Natural Resources. For additional information on the species listed in the above table, including wildlife and other benefits, see .
While some drought tolerant non-native perennials would be expected to thrive on extensive green roofs, to our knowledge very few if any green roofs in Minnesota have attempted to grow non-native perennials on extensive green roofs.
Many vegetables and herbs also thrive on green roofs, many in growing medium as little as four inches deep, including herbs, tomatoes, peppers, and lettuce. Because they are annuals, vegetables require considerably more maintenance than other extensive green roof plants. If they are fertilized, they will likely increase nutrient content of runoff from the roof, so they may not be ideal for stormwater projects where leaching of nutrients is a concern. If all runoff from the green roof is harvested and re-used on the roof, fertilization will not affect down stream water bodies.
Aside from growing food in a built-in-place green roof, food can also be grown in containers or hydroponically on a green roof, or on a green or living wall.
The St Paul, MN, fire station is a premier local example of growing food on a green roof. Many other examples of growing food on residential and commercial green roofs can also be found in the US and Canada, including
Several on-line references provide more detail about rooftop agriculture, including, for example, Guide to Setting Up Your Own Edible Rooftop Garden, published by Alternatives and the Rooftop Garden Project (2008).
Other recent publications on rooftop agriculture include