Plant lists for green roofs

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.

Growing sedums and other succulent plants on green roofs

Photo of sedums on the Target Center Arena green roof in Minneapolis, MN. Image Courtesy of The Kestrel Design Group, Inc.

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

• Getter, K.L.; Rowe, D.B. 2008. Selecting Plants for Extensive Green Roofs in the United States. Michigan State University Extension Bulletin E-3047.
• Snodgrass, E.C. and L.L. Snodgrass. 2006. Green Roof Plants: A Resource and Planting Guide. Timber Press.

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

• Butler, C., and C.M. Orians. 2011. Sedum cools soil and can improve neighboring plant performance during water deficit on a green roof. Ecological Engineering. 37(11). 1796–1803.
• Rowe, D. Bradley, Kristin L. Getter, and Angela K. Durhman. 2012. Effect of green roof media depth on Crassulacean plant succession over seven years. Landscape and Urban Planning (Elsevier) 104:310-319.
• Whittinghill, L.J. and D.B. Rowe. 2011. Salt tolerance of common green roof and green wall plants. Urban Ecosystems. 14(4):783-794.

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

Growing native species on green roofs

Similarities between bedrock bluff prairies and green roof habitats. Image courtesy of The Kestrel Design Group, Inc.

Native plants on Minneapolis City Hall green roof, Minneapolis, MN. Image Courtesy of The Kestrel Design Group, Inc

Native Plants on Target Center Arena Green Roof, Minneapolis, MN. Image Courtesy of The Kestrel Design Group, Inc.

Native Plants on Phillips Eco-Enterprise Green Roof. Image Courtesy of The Kestrel Design Group, Inc.

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 [1].

Growing non-native perennials and grasses on green roofs

While some drought tolerant non-native perennials would be expected to thrive on extensive green roofs, to our knowledge very little if any green roofs in Minnesota have attempted to grow perennials on extensive green roofs.

Growing edible plants on green roofs

Many vegetables and herbs also thrive on green roofs, many in growing medium as little as four inches deep, such as, for example, 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

• Brooklyn Grange, a one acre (43,000 square foot) farm in Queens rooftop farming and intensive green roofing business located on two roofs in New York City, which grows over 40,000 pounds of organically-cultivated produce per year
• Eagle Street Rooftop Farm 6,000 square foot green roof organic vegetable farm located atop a warehouse rooftop owned by Broadway Stages in Greenpoint, Brooklyn

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

• Mandel, L., 2013, EAT UP; The Inside Scoop on Rooftop Agriculture. New Society Publishers: Gabriola Island, BC, Canada.
• Whittinghill, L.J. and D.B. Rowe. 2012. The role of green roof technology in urban agriculture. Renewable Agriculture and Food Systems 27(4):314-322.
• Whittinghill, L.J., D.B. Rowe, and B.M. Cregg. 2013. Evaluation of vegetable production on extensive green roofs. Agroecology and Sustainable Food Systems 37(4):465-484.
• Additionally, Green Roofs for Healthy Cities offers a half day course on Rooftop Agriculture: [(http://www.greenroofs.org/index.php/education/halfdaycourses). Introduction to Rooftop Urban Agriculture]

References

• Butler, C., & Orians, C. M. 2011. Sedum cools soil and can improve neighboring plant performance during water deficit on a green roof. Ecological Engineering,37(11): 1796–1803.
• Carroll, K. 2013. Personal Communication.
• Durhman, A.K. D. B. Rowe, and C. L. Rugh. 2007. Effect of Substrate Depth on Initial Growth, Coverage, and Survival of 25 Succulent Green Roof Plant Taxa. HORTSCIENCE 42(3):588–595. 2007.
• Durhman, A.K., D.B. Rowe, and C.L. Rugh. 2006. Effect of watering regimen on chlorophyll fluorescence and growth of selected green roof plant taxa. HortScience 41:1623–1628.
• Dvorak, B, and K. Carroll. 2008. Chicago City Hall Green Roof: Its Evolving Form and Care. Greening Rooftops for Sustainable Communities Conference Proceedings, Baltimore, MD.
• Dvorak, B., and A. Volder. 2010. Green Roof Vegetation for North American Ecoregions: A Literature Review. Landscape and Urban Planning 96: 197-213.
• Getter, K.L.; Rowe, D.B. 2008. Selecting Plants for Extensive Green Roofs in the United States. Michigan State University Extension Bulletin E-3047. Downloaded May 1, 2013 from http://www.hrt.msu.edu/greenroof/PDF/08%20GetterRoweExtensionBulletin.pdf
• Grese, R. 2008. Personal Communication.
• Hawke, R. 2013. Personal communication.
• Kestrel Design Group. 2013. Personal Communication.
• Mandel, L., 2013, EAT UP; The Inside Scoop on Rooftop Agriculture. New Society Publishers: Gabriola Island, BC, Canada.
• Monterusso, M.A., D.B. Rowe, and C.L. Rugh. 2005. Establishment and persistence of Sedum spp. and native taxa for green roof applications. HortScience 40:391–396.
• Rowe, D. Bradley, Kristin L. Getter, and Angela K. Durhman. 2012. Effect of green roof media depth on Crassulacean plant succession over seven years. Landscape and Urban Planning (Elsevier) 104: 310-319.
• Rowe, D.B., C.L. Rugh, and A.K. Durhman. 2006. Assessment of substrate depth and composition on green roof plant performance. Proc. of 4th North American Green Roof Conference: Greening Rooftops for Sustainable Communities, Boston, Mass., 10–12 May 2006. The Cardinal Group, Toronto.
• Snodgrass, E.C. and L.L. Snodgrass. 2006. Green Roof Plants: A Resource and Planting Guide. Timber Press.
• Sutton, R.K.; J.A. Harrington; L. Skabelund; P. MacDonagh; R. R. Coffman; and G. Koch. 2012. Prairie-Based Green Roofs: Literature, Templates, and Analogs. Journal of Green Building 7(1):143-172.
• Sutton, R.; B. Rowe;G. Acomb; J. Lambrinos; P. MacDonagh; R. Hawke. 2012. New Plant Performance for 21st Century Green Roof Ecosystems. Cities Alive Conference, Chicago IL.
• Sutton, R. 2011. Personal Communication.
• Torrance, S.; B. Bass, S. MacIvor and T. McGlade in conjunction with Toronto City Planning Division. No publication year given. City of Toronto Guidelines for Biodiverse Green Roofs. Downloaded May 1, 2013 from http://www.toronto.ca/greenroofs/pdf/biodiversegreenroofs_2013.pdf
• VanWoert, N.D., D.B. Rowe, J.A. Andresen, C.L. Rugh, and L. Xiao. 2005. Watering regime and green roof substrate design affect Sedum plant growth. HortScience 40:659–664.
• Whittinghill, L.J. and D.B. Rowe. 2012. The role of green roof technology in urban agriculture. Renewable Agriculture and Food Systems 27(4):314-322.
• Whittinghill, L.J., D.B. Rowe, and B.M. Cregg. 2013. Evaluation of vegetable production on extensive green roofs. Agroecology and Sustainable Food Systems 37(4):465-484.
• Whittinghill, L.J.; D.B. Rowe, 2011. Salt tolerance of common green roof and green wall plants. Urban Ecosystems 14(4):783-794.