grasses & sedges: focus on function and design 1 · ‐allan armitage. greenhouse grower,...

7/9/2015

Grasses & Sedges: Focus on Function and Design 1

Green InfrastructureHarness the Power of Grasses & Sedges

Shannon Currey, Marketing DirectorHoffman Nursery, Inc.Cultivate’15 • July 13, 2015

Photo: Stephen H. Blake, P.E., Artifex Environmental Design, Inc.

Hoffman Nursery, Inc.Specializing in ornamental & nativegrass liners for the wholesale trade

Rougemont, North Carolina

Overview

• Emerging field offers opportunities

• What kinds of plants make sense?

• Examples of projects and plants

• Areas where info is needed

• Next steps

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Mon. 7/13 1:30 PM - Ballroom 4 Perennials & Grasses for Green Infrastructure Shannon Currey

steve

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AmericanHort provides this on a “Not For Publication” basis. Publication of this information, in part or whole, is only permissible through written permission of the author(s).

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GREEN INFRASTRUCTURE

An Emerging Field for the Green Industry

• We could be growing more plants that would work

• Previously focused more on ornamental value

• Need to look at functionality, too

Horticultural economist Dr. Charlie Hall calls green infrastructure a game changer for our industry.

“We’ve got to emphasize the economic benefits, the environmental/ecosystem service benefits, and the health and well‐being benefits [of plants], not just the fact that they’re pretty.”

“What’s the Next Industry Game Changer?”Grower Talks, July 2015

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Survey: Plants in Green Infrastructure (GI)

• At 2014 NC Low Impact Development Summit, surveyed LID/GI practitioners

• Respondents indicated plants play a major role in LID/GI

• Difficulties to overcome in realizing the full potential of plants for LID/GI.

“Growing the Urban Landscape Market,” American Nurseryman, Nov. 2014

GI Features Used Most

Bioretention 88%

Vegetated swales 66%

Wetlands 57%

Wet detention 49%

Infiltration 46%

Photo: EPA


Difficulties with GI Features

Maintenance 57%

Plant survival 54%

Weeds 48%

Infiltration 35%

Plant appearance 34%

Public complaints 34%

Media/mulch 34% http://nemonet.uconn.edu/


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North CarolinaMuseum of Art

Raleigh, NCPond Project

Photo: Stephen H. Blake, P.E., Artifex Environmental Design, Inc.

2 years after planting

5 years after planting

Who Specifies Plants?

Landscape Architect 67%

Engineer 39%

Horticulturist 19%

Landscape Designer 16%

Contractor 9%


GI: An Emerging Field

• Guidelines still in development

• Recommendations and methodology inconsistent

• Plant lists are limited

• Design of features depends on water quality goals of the project and conditions at the site

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GRASSES, SEDGES, AND RUSHES

A Quick Recap

True Grasses

• In the Poaceae family

• Widest distribution of all flowering plant families

• Adapted to survive in extreme conditions

• Highly efficient, fibrous root systems

• Many maintain their habit when dormant

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Panicum virgatum

Photos: The Land Institute

Andropogon gerardii

Sedges• Mostly in the genus Carex

• Distributed throughout the world

• Many native sedges do best in organic soils with adequate moisture

• Range from shade loving to sun tolerant

7/9/2015Great Grasses for Southern Landscapes

Rushes

• In the genus Juncus

• Typically inhabit wet or moist places

• Evergreen in many climates

SELECTING PLANTS

What kinds make sense?

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What to Consider?

Soil conditions

• Improve drainage

• Prevent erosion

• Thick crowns and/or rhizomatous growth

• Continues to function during dormancy

What to Consider?

Moisture availability

• Grasses often need good drainage, especially in winter

• Sedges species have a wide range

• Minimize water use, but readily take up water when present

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What to Consider?

Sun exposure

• Most grasses do best in full sun

• Some sedges tolerate or even prefer shade

• Dependent on region

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What to Consider?

Contribution to plant community

• Pioneer species

• Form a matrix for other perennials

• Native species provide shelter, food, and nesting sites for wildlife

• Seasonality

What to Consider?

Tolerance for pollutants

• Metals, phosphorus, nitrogen

• Salt tolerance in colder climates

Phytoremediation potential

• Hydrocarbons (from fossil fuels)

• Metals

FOCUS ON FUNCTION

Examples of GI projects & plants

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Bioretention/Rain Gardens

• Typically shallow, vegetated depressions

• Provide storage, evapotranspiration, and treatment of runoff

• Store water and drain within 24‐48 hours

• Will dry out when rain is sparse

Bioretention &Rain Gardens

• Plants should be able to handle both wet and dry conditions

• Tolerate pollutants from surrounding land use

• Site often divided into zones – choose plants according to zones

Diagram Excerpt: http://www.svrdesign.com/

• Lowest: plants will experience standing water & fluctuating water levels

• Middle:mainly fluctuating water levels

• Upper: usually drier; upland species can do well

LowestMiddleUpper

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NCMA Pond Project

• Lower

– Juncus effusus

– Carex stricta

– Scirpus cyperinus

• Middle– Panicum ‘Northwind’

– Spartina bakeri

• Upper– Schizachyrium scoparium

– Panicum ‘Shenandoah’

– Sorghastrum nutans

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Juncus effususCommon Rush

Vase shape adds structure

Wide distribution – found throughout North America

Wildlife cover; nesting sites for birds; food for birds, mammals & caterpillars; pollen for pollinators.

Throughout N. America

Adapts to a wide range of habitats & soil textures

Can spread and naturalize

Wildlife cover; nesting sites; food for birds & caterpillars.

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Carex vulpinoideaFox Sedge

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Cool season grass

Tolerates varying soil types and pH ranges

Throughout upper East Coast, Midwest, Western US & Canada

Nesting sites; food for caterpillars, birds & mammals

Deschampsia cespitosaTufted Hair Grass

Throughout Eastern North America

Thrives in wet areas

Showy seed heads

Tolerates light shade

Carex grayiGray’s Sedge

Panicum virgatum & cvs.

• Native to prairies, open woods & brackish marshes in N. America

• Heat and drought tolerant

• Hardy to Zone 4

• Adapt to a wide variety of conditions

• Food, cover & nesting sites for birds; cover for small mammals

Switchgrass

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Schizachyrium scoparium & cvs.

• Native bunchgrass of prairies and open woods in North America

• Tolerates a wide range of soil conditions

• Striking fall color and luminous inflorescences

• Food for birds, mammals & caterpillars; cover for birds & small mammals; nesting sites; pollen for pollinators

…I expect to see Little Bluestem appear far more on landscape drawings in the future.

‐Allan Armitage

Greenhouse Grower, 1/28/15

Little Bluestem

Syme Rain GardenNC State Campus, Raleigh, NC

Syme Rain GardenNC State Campus, Raleigh, NC

Artists’ BackyardNC State Campus, Raleigh, NC

Artists’ BackyardNC State Campus, Raleigh, NC

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Indianapolis Museum of Art

Green Roofs

Plants must:

• Be heat and drought tolerant

• Provide consistent coverage

• Use nutrients efficiently

• Have non‐aggressive roots

Green Roofs

• In some regions, high rainfall with extended periods of saturation and humidity

• Select plants for high water use and drought tolerance

• Expect low fertility and shallow soil conditions

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Tolerant of high pH

Cold hardy

Adaptable

Tufted habit and fine texture

Sesleria autumnalisAutumn Moor Grass

7/9/2015Great Grasses for Southern Landscapes

Bouteloua gracilisBlue Grama

Great Plains, Southwestern US, Midwest US & Canada

Appealing seed heads

Tolerates poor soil, full sun, dry conditions

Cover; nesting sites; food for birds, mammals & caterpillars

Bouteloua gracilis ‘Blonde Ambition’

PP22048

Blue Grama

Tough, adaptable

Tolerates poor soil and drought

Abundant seed heads

Long‐lasting attractiveness

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Most of US and Canada on rocky open slopes, woodlands, and forest openings

Drought tolerant

Tolerates sandy and clay soil

Intricate, hanging flowers

Bouteloua curtipendulaSide Oats Grama

Schizachyrium scoparium cvs.

• Native bunchgrass of prairies and open woods in North America

• Tolerates a wide range of soil conditions

• May flop with shade, excess fertility, or too much moisture

• Striking fall color and luminous inflorescences

Private residence in the North Carolina mountainsPrivate residence in the North Carolina mountains

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Private residence on Kiawah Island, SCPrivate residence on Kiawah Island, SC

Swarthmore College, PennsylvaniaSwarthmore College, Pennsylvania

Photo: Jared Barnes

What’s Needed?

• Evaluation of a wider range of plants

• Phytoremediation potential of specific plants

• Optimum sizes for planting

• Optimum planting density

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Rain Garden Research at NC State Univ.

• Vegetation significantly affects remediation.

• Species and cultivar selection affect the level of sequestration.

• Plant diversity allows for more remediation to occur.

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Evaluation

Charlotte Brody Discovery GardenSarah P. Duke Gardens

Durham, NC

Charlotte Brody Discovery GardenSarah P. Duke Gardens

Durham, NC

• Sustainable Sites Initiative Pilot Project

• Case Study Investigation funded by Landscape Architecture Foundation

Suggestions for Growers

• Research and identify plants you’re growing or could grow that would fit

• Expand offerings if it makes sense

• Check back in with projects to get feedback

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Suggestions for Landscape Contractors

• Get training in GI installation and maintenance

• Work closely and early with plant supplier

• Act as bridge between grower and designer

Suggestions for Design Professionals

• Use suppliers as a resource

• Communicate frequently and convey project parameters

• Work closely and early with contractors and plant suppliers

Photo: EPA

Landscape Architecture, May 2015When the market emerges, and when the products the market needs for sustainable landscaping are ready, the landscape architecture profession should be ready to go...knowing the plants better, and working more closely with growers.

‐Carol E. Becker, Landscape Designer

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EPA Green Infrastructure Roadshow

http://epa.gov/owow/ocpd/green_infrastructure_roadshow.pdf

EPA 842‐R‐15‐002

January 2015

The Encyclopedia of Grasses for Livable Landscapes, Rick Darke, 2007, Timber Press

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The Living Landscape,Rick Darke & Doug Tallamy, 2014, Timber Press

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Conclusions

• GI projects need someone who knows the plants and can match to site conditions.

• Need partnership between designers, contractors, and growers

• We have an opportunity while the field is still developing.

Thank you for your attention!

hoffmannursery.com

[email protected]

www.mapyourshow.com/MYS_Shared/cultivate15/handouts/Mon_Ballroom4_GH315_Currey.pdf

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