The Power of Grasses & Sedges

Green Infrastructure

Harness the Power of Grasses & Sedges™

Green infrastructure uses vegetation, soils, and natural processes to manage water and create healthier urban environments.
–U.S. Environmental Protection Agency

The way people think about plants and the way our communities manage water are changing. Green infrastructure (GI) may become the new normal. GI uses natural features to manage water while providing additional benefits, such as recreation space, support for wildlife, and increased aesthetic value.

According to Dr. Charlie Hall, a horticultural economist from Texas A&M University, “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.” Talking about what plants can do for us and treating them as a necessity rather a luxury is key for our industry.

We and our customers are seeing projects that can be classified as green infrastructure more often. We think it’s worth knowing more about them. The shift to GI presents our industry with unique opportunities. It’s time to think about how your growing program or business model fits this new market.

Grasses, sedges, and rushes play a major role in green infrastructure and low impact development. Their fibrous root systems anchor soil, slow down water flow, and increase infiltration. They help remove pollutants, and many are well-adapted to the demands of GI features.

So, you see…we’re pretty interested in water and green infrastructure these days. If you're ready to jump right to the plants, download our Green Infrastructure Guide and Plant Chart.

Bioswales like this one at Sarah P. Duke Gardens in Durham, North Carolina capture runoff, slow water flow, and increase infiltration. They also support wildlife and increase ecological diversity.

A New Take on Infrastructure

As the cost of repairing aging stormwater infrastructure becomes prohibitive, communities are choosing to manage stormwater and urban spaces differently:

by routing stormwater runoff through swales filled with grasses, sedges, and wildflowers rather than concrete culverts
by treating stormwater with rain gardens, green roofs, and green streets
by installing meadow plantings instead of turfgrass to use less water, less fertilizer, and fewer pesticides.

Many green infrastructure features depend on plants. Some treat and manage stormwater directly, such as bioretention. Others use alternatives to hardscape or turfgrass to slow runoff and let the water soak into the soil, such as prairie plantings.

In the information below, you’ll find a guide to common features that use plants in their designs.

The field is relatively new, so definitions and terminology vary depending on where you are located, who’s making the rules, or which manual you’re consulting. And as the field evolves, new features like regenerative stormwater conveyances emerge. In addition, an approach called low impact development overlaps with green infrastructure and employs many of the same features.

Green Infrastructure Features

Bioretention & Rain Gardens are vegetated, shallow depressions in the ground designed to provide storage, evapotranspiration, and treatment of stormwater runoff. They drain within 24-48 hours and dry out when rain is sparse.

Bioretention: usually large in scale. Includes engineered media, drop inlets, and under drains.
Rain gardens: typically small, excavated depressions in a residential or non-commercial setting.
Both store runoff and will drain within 24-48 hours. When rain is sparse, they will dry out.
Plants must be able to handle both wet and dry conditions and tolerate pollutants from surrounding land use.
Sites are often divided into zones. Plants for biorientation and rain gardens should be chosen to fit the appropriate zone.
- The lowest: standing water and fluctuating water levels.
- The middle zone: mainly fluctuating water levels.
- The upper zone: usually drier; upland species can do well.

Bioswales & Vegetated Swales are gently sloping channels planted heavily with a variety of species, as opposed to grassed swales, which contain only turfgrass.

Treat water from surrounding areas by slowing it down, filtering out trash and pollutants, and allowing for infiltration and evapotranspiration.
Heavily planted with a variety of species, as opposed to grassed swales, which contain only turfgrass.
Plants for the bottom of a bioswale need to be able to handle fluctuating conditions between wet and dry.
Plants for the upper slopes need to be tolerant of wet conditions but also be able to tolerate consistent dryness between rain events.
Plants need to have strong, extensive root systems and establish quickly.

Erosion Control plants keep soil in place and improve water quality by keeping sediment and pollutants out of waterways.

With their branching, fibrous root systems, grasses and sedges are good choices for stabilizing soil and reducing erosion, especially on banks and slopes.
The species listed need little maintenance, and most are quick to establish, which can be critical on steep inclines, large embankments, or uneven ground.

Green Roofs help manage stormwater, reduce energy consumption, provide wildlife habitat, and increase roof lifespan. Green roof systems typically have low fertility and shallow soil conditions.

Require plants that are heat and drought tolerant, provide consistent coverage, use nutrients efficiently, and have non-aggressive root growth.
In the Southeast, roofs can receive large amounts of rainfall and have extended periods of saturation and humidity. Plants for these situations should be selected for both high water use and drought tolerance.
Low fertility and shallow soil conditions should be expected.

Lawn Alternatives create a low ground cover that does not need regular mowing or fertilizing. Compared to turfgrass, they reduce resource use and maintenance burden.

Can reduce resource use and the maintenance burden of turfgrass. Many handle dry conditions once established and do not need supplemental irrigation.
Can tolerate being mowed two-three times a season if desired, but only need cutting back once a year in late winter before new growth appears.
Are most appropriate for areas that don’t get heavy foot traffic.

Meadow & Prairie Plantings reduce stormwater runoff, add green spaces in urban areas, and support a rich variety of wildlife. Replace a stretch of turfgrass with a visually compelling meadow or prairie planting.

Plantings are usually open communities of grasses and wildflowers, with few trees.
Grasses and sedges for these plantings cover a wide variety of conditions. Most do well in low-fertility soils, thrive in full sun, and are drought tolerant.
A few do well in wet meadows. Check the individual listings for help in matching your site conditions.

Grasses, Sedges, and Rushes for Green Infrastructure

Grasses have fibrous, branching root systems that help hold soil, improve drainage, and slow water flow. They keep their habit when dormant, so they continue to perform these functions during winter. Grasses are rarely picky about soil pH and are adaptable to a range of environments. All this makes them especially useful for these kinds of projects.

We’ve selected plants that should perform well in the growing environments described above. Other grasses and sedges could also work, but for now we’re including our best suggestions.

These lists are starting points. Not every plant on a list will work for everyone. It’s still important to know the site and be familiar enough with the plants to match them to your site. Plants within each list have preferences for moisture and light. Some are native to specific regions or better adapted to particular areas of the country than others.

Many green infrastructure guidelines and manuals for stormwater best management practices (BMPs) recommend using native plants. Thus, our lists include primarily North American species and cultivars. Introduced plants can also be a good choice if conditions warrant.

You can download our Green Infrastructure Guide and Plant Chart, or get the most up-to-date lists here:

Plants suggested for:

To Learn More about Green Infrastructure & Low Impact Development

For tons of info on a range of topics, try the Environmental Protection Agency (EPA) site on green infrastructure. To join greenstream, an EPA listserv featuring updates on green infrastructure publications, training, and funding opportunities, send an email to join-greenstream@lists.epa.gov.
Green Roofs for Healthy Cities (GRHC) is the North American industry association for the green roof and wall sectors. They develop and protect the market by increasing the awareness of the economic, social and environmental benefits of green roofs, green walls, and other forms of living architecture through education, advocacy, professional development and celebrations of excellence.
To see evaluations of performance and ways to show value and make the case for sustainable landscape solutions, go to the Landscape Architecture Foundation's Landscape Performance Series.
The Low Impact Development Center's Urban Design Tools site has guidance for local governments, planners, and engineers.
The American Society of Landscape Architects addresses shows examples of sustainable landscapes across the country in Designing for Future: Sustainable Landscapes.
Down-to-earth reasons for stormwater innovations in urban areas in this article.
Read about the connection between real estate value and green infrastructure in, "Harvesting the Value of Water," from the Urban Land Institute.
Research on the connection between green spaces and human health at the University of Illinois at Champagne-Urbana Landscape and Human Health Laboratory.
North Carolina’s stormwater design manual gives technical guidance to professionals on stormwater control measures (SCM). To see which grasses, sedges, and rushes are in the NC Stormwater Design Manual and which ones we grow, download our PDFs: Grasses, Sedges, and Rushes for NC Stormwater Wetlands and Grasses, Sedges, and Rushes for NC Bioretention Cells . To see the full lists, go to the NC Stormwater Design Manual webpage.