Ornamental Grasses for Rain Gardens
Randy S. Nelson1, Esther E. McGinnis2, and Aaron Lee M. Daigh3 1University of Minnesota, Extension Educator, Clay County. 2Associate Professor, Extension Horticulturist, Plant Sciences Department, NDSU, Fargo. 3Associate Professor of Soil Physics, Soil Science Department, NDSU, Fargo. Rain Garden
Photo: http://www3.apwa.net/Resources/Reporter/Articles/2005/9/Rain-Gardens-Strategic-puddles-for-stormwater-management
Parking Lot Downspout garden
https://stormwater.pca.state.mn.us/index.php?title=University_of_Minnesota_Arbor etum_-_runoff_model_and_rain_gardens https://emswcd.org/in-your-yard/rain-gardens/
Problem Scientific name Common name Wetland indicator status (Great Plains) • No scientific research on which to base Carex hystericina Porcupine sedge Obligate wetland recommendations Carex Palm sedge Obligate wetland muskingumensis • Recommendations based merely on Carex annectens Yellow fox sedge Facultative wetland wetland status Carex grayi Gray’s sedge Facultative wetland Carex brevior Plains oval sedge Facultative • Doesn’t acknowledge that rain garden Carex sprengelii Sprengel’s sedge Facultative Upland plants may experience drought too Carex pensylvanica Pennsylvania sedge Upland
*2-day flooding, 7-day flooding *Mild drought (15% VWC), moderate drought (10% VWC), and severe drought (5% VWC) *several cycles
1 Palm sedge 2 day flood; Plains oval sedge 2 day flood; obligate wetland plant facultative wetland plant
Control 15% VWC 10% VWC 5% VWC Control 15% VWC 10% VWC 5% VWC 1 1 1 2 1 2 3 4
Ornamental grasses Grasses used in study Wetland Common indicator Scientific name name status (Great Plains) Tufted hair Facultative Deschampsia cespitosa ‘Pixie Fountain’ Tufted hair grass grass wetland Switchgrass Little bluestem ‘Blue Photo: Randy S. Nelson Panicum virgatum ‘Northwind’ Switch grass Facultative ‘Northwind’ Heaven’ Big bluestem Facultative Andropogon gerardi ‘Red October’ Big bluestem ‘Red October’ upland Chinese Facultative Miscanthus sinensis ‘Purpurascens’ silvergrass upland Little Facultative Schizachyrium scoparium ‘Blue Heaven’ bluestem upland Blue grama Bouteloua gracilis ‘Blonde Ambition’ Upland grass Feather reed Calamagrostis x acutiflora ‘Karl Foerster’ Upland Blue grama grass grass Photos by Esther E. McGinnis Chinese silvergrass unless noted otherwise. Wetland indicator status, designation, and description are from Lichvar et al., 2016. Feather reed grass ‘Karl Foerster’ ‘Purpurascens’
Design Shoot mass – species x drought – 7 grass species – 2 flood durations; 2- and 7-day – 2 drought setpoints 14% (mild) and 7%(severe) volumetric water content (VWC) – Well-watered control – At least four cycles
FACW FAC FACU FACU FACU UPL UPL
2 Root mass – species x drought Chinese silver grass ‘Purpurascens’
14% VWC
Control 2 day 7 day FACW FAC FACU FACU FACU UPL UPL 1 1 1
Chinese silver grass ‘Purpurascens’ Visual damage rating - species
7% VWC
Control 2 day 7 day FACW FAC FACU FACU FACU UPL UPL 1 8 10
Miscanthus ‘Purpurascens’ Andropogon gerardii ‘Red October’ Purple Flame Grass Big bluestem • Red flame grass • Zone 4 • Warm season grass • 4-6’ tall • Zone 3; hardiest of the • Warm season grass Miscanthus spp. • Spectacular fall color • Reliable fall color • Clump former • Small rhizomes will • Will self seed expand the width of the plant
3 Schizachyrium scoparium ‘Blue Heaven’ Panicum virgatum ‘Northwind’ Little bluestem
*Doesn’t lodge *May not be hardy in northern areas *Fall color! Zone 3; 4-5’, PPA 2014
Calamagrostis x acutiflora Bonus plant: Bouteloua gracilis ‘Karl Foerster’ ‘Blonde Ambition’ • Clump, 4-5 feet tall • Less tolerant of cyclical flooding and drought • Cool season grass than other grasses • PPA 2002 • Great for saline soils! • Hardy to Zone 3 • Can take more flooding than we expected
Photo courtesy of Walters Gardens, Inc.
‘Blonde Ambition’ Conclusion • Highly adaptable to cyclical flooding and drought • Severe drought reduced relative plant height, shoot count, total biomass and ornamental value • May need supplemental irrigation during times of drought
• More results to come: submersion study, salt tolerance study, petroleum tolerance study
Photo courtesy of Walters Gardens, Inc.
4 Acknowledgment
• ND Specialty Crop Block Grant • Please take our survey!
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