Sustainable Landscaping
healthy lawn care
rain gardens

 

 


Demonstration Rain Garden. North Kingstown Town Hall, June 2005.

Visit our page on the Demonstration Rain Garden at the North Kingstown Town Hall.

View our brochure about the garden (print version)

What is a Rain Garden
How to plan, install, maintain -
additional resources
Plants
Other examples - CT

What is a Rain Garden?

Rain gardens are becoming increasingly popular in the home landscape. A rain garden is a natural or dug shallow depression designed to capture and soak up stormwater runoff from your roof or other impervious areas around your home like driveways, walkways, and even compacted lawn areas. They can be used as a buffer to shoreline areas to capture runoff from the home landscape before it enters a lake, pond, or river. The rain garden is planted with suitable trees, shrubs, flowers, and other plants allowing runoff to soak into the ground and protect water quality.

In addition to adding beauty to your home landscape, rain gardens can also help protect water quality, by reducing stormwater runoff from your house lot. Stormwater runoff is considered one of the main sources of water pollution nation-wide. As watersheds become developed, urbanization and an increase in paved surfaces such as parking lots, driveways, and rooftops increase stormwater runoff causing rainwater to run off quickly into storm drains and surface waters.

Stormwater runoff can result in:

- Overall reduction in groundwater recharge.

- Long-term lowering of groundwater tables and loss of stream flow during dry weather.

- Increased erosion.

- Increased water quality impacts caused by pollutants in stormwater runoff.

- Flooding – especially more frequent “flash” flooding.

A rain garden will allow the runoff generated on your property to infiltrate into the ground and help to reduce potential water quality problems. While your individual rain garden may seem like a small contribution, collectively, rain gardens can produce water quality benefits.

Benefits of Rain Gardens

In addition to reducing and filtering stormwater runoff and increasing groundwater recharge, rain gardens provide many other benefits including:



Provide habitat for wildlife and, with the proper plants, increase the number and diversity of birds and butterflies for those who enjoy watching them.
Provide an attractive and creative alternative to traditional lawn landscapes.
Require less maintenance than lawns because they do not need to be mowed, fertilized, or watered once established.
Increase property values with creative landscaping designs.
Reduce storm drain overload and flooding if adopted on a community or neighborhood scale.

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Designing and Installing a Rain Garden

There are different methods for designing and sizing your rain garden. Review these information sources for details and instruction on rain garden creation:

URI Cooperative Extension Resources:
Rain Gardens: A Design Guide for Homeowners in Rhode Island
Rain Garden Service Project Manual for Students

Rain Gardens in Connecticut: A Design Guide for Homeowners
UConn Cooperative Extension System

Haddom, CT research/demonstration rain garden
University of Connecticut NEMO Program

Rain Garden Information Center
Rutgers - State University of New Jersey

Landscapes for Maine: Adding a Rain Garden to Your Landscape University of Main Cooperative Extension

Rain Gardens: A How-to Manual for Homeowners. Wisconsin

Instructional Flyer - Center for Watershed Protection

Take time to completely read through these references as your first step to creating a rain garden. The sources describe various ways to design and install a rain garden and the method you choose will depend on your needs and desires.

Where you choose to locate the rain garden is important and you should take the time to assess the conditions in your yard to determine the most appropriate place.

• The rain garden should be at least 10 feet from the house so infiltrating water doesn’t seep into the foundation.
• Do not place the rain garden within 15 feet of a septic system, or 25 feet of a well or water supply.
• It is better to build the rain garden in full or partial sun, not directly under a big tree.
• It may be tempting to put the rain garden in a part of the yard where water already ponds. Don’t! The goal of a rain garden is to encourage infiltration, and your yard’s wet patches show where infiltration is slow.
• Water should only pool in your rain garden for several hours after rainfall before it is absorbed. This is important for both the plants as well as mosquito concerns.

Choosing the Right Plants

It is best to use native, non-invasive species that are resistant to the stress from both brief periods of pooling as well as dry periods between rainfall events. A variety of plants with large root structures will make your rain garden more effective and less susceptible to disease. It is also better to use plants with a developed root structure instead of starting plants by seed. Seeds will have a hard time establishing in the conditions of a rain garden and will also leave the soil exposed and prone to erosion. We have provided a list of suggested plants below.

Rain Garden Cost

The cost of a rain garden can vary greatly. If you do all of the labor yourself, the cost will depend on the number and type of plants you use, as well as any additional materials you may have to purchase such as mulch, crushed stone, roof gutter downspout extensions, or tools for digging. If you hire a landscaper or someone else to install the rain garden the cost will be more and will be a function of the size and depth of the rain garden as well as the number and type of plants used.

Rain Garden Maintenance

While the plants in your rain garden are young and becoming established they may require some supplemental water during dry periods, though this should only be the case for the first year. For more information on proper watering, view our Water Wisely factsheet. Some weeding may also be required the first year until the plants fill out and can out compete weeds.

Once the rain garden has become established maintenance is minimal and will generally only include periodic mulching, pruning and thinning, and plant replacement. Be sure to inspect your rain garden periodically during and/or immediately after rainfall events to be sure the rain garden is working as designed.

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The information in this factsheet is adapted from the following sources:

- Rain Gardens: A How-to Manual for Homeowners. Roger Bannerman and Ellen Considine. Wisconsin.
- Community Watersheds: Educating Watershed Constituents. Center for Watershed Protection.
- Creating a Rain Garden in Your Yard. Town of Maplewood, Minnesota.

Special thanks to the following people for their information and review of this factsheet:

- Dr. Brain Maynard, URI Department of Plant Sciences
- Roseanne Sherry, URI Master Gardener Coordinator
- Lisa Gould, Rhode Island Natural History Survey, College of the Environment and Life Sciences

The following photos are courtesy of the University of Connecticut to show additional examples of a rain garden.


Rain gardens are designed to pond for a few hours at a time. Ponding should not occur for more than six hours. Jordan Cove Urban Watershed Project, Waterford, CT.



Rain Garden installation containing a young River Birch. University of Connecticut, Michael E. Dietz, Department of Natural Resources Management and Engineering.

For more information, visit the Haddom, CT research/demonstration rain garden, University of Connecticut. Site provides data on pollutant removal.

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Suggested Rain Garden Plants

This plant list includes plants that can tolerate temporary pooling of rainwater as well as dry periods. Most of the plants are native species and those that are known for attracting butterflies or hummingbirds are noted. Some of the native plants included in this list may not be readily available at all garden centers. Call your local nurseries and garden centers to find out availability. You can also contact the Rhode Island Wild Plant Society, www.riwps.org for more information about native plant sources.

The Rhode Island Coastal Plant Guide includes plants that are suitable for rain gardens.

Information about many of these plants can also be found in the URI Cooperative Extension Sustainable Tree and Shrub Manual.

* attractive to butterflies and/or hummingbirds

Trees
Red Maple, Acer rubrum
Shadblow, Amelanchier arborea
River Birch, Betula nigra
Gray Birch, Betula populifolia
Red-Panicled Dogwood, Cornus racemosa
White Ash, Fraxinus americana
Green Ash, Fraxinus pennsylvanica
Witchhazel, Hammamelis virginiana
Red Cedar, Juniperus virginiana
American Sweetgum, Liquidambar styraciflua
Tupelo, Nyssa sylvatica
American Hop Hornbeam, Ostrya virginiana
Swamp White Oak, Quercus bicolor
Pin Oak, Quercus palustris
Red Oak, Quercus rubra

Shrubs and Vines
Red Chokeberry, Aronia arbutifolia
Black Chokeberry, Aronia melanocarpa
Wild Clematis, Clematis virginiana
Sweet Pepperbush, Clethra alnifolia
Red Twig Dogwood, Cornus sericea
Black Huckleberry, Gaylussacia baccata
Inkberry, Ilex glabra
American Holly, Ilex opaca
Winterberry Holly, Ilex verticillata
Mountain-laurel, Kalmia latifolia
*Northern Spicebush, Lindera benzoin
Trumpet Honeysuckle, Lonicera sempervirens
Northern Bayberry, Myrica pensylvanica
Virginia Creeper, Parthenocissus quinquefolia
Rosebud Azalea, Rhododendron periclymenoides
*Great Rhododendron, Rhododendron maximum
Shining Sumac, Rhus copallinum
*Small Pussy-Willow, Salix humilis
Elderberry, Sambucus canadensis
American Arborvitae, Thuja occidentalis
Late Lowbush Blueberry, Vaccinium angustifolium
Highbush Blueberry, Vaccinium corymbosum
Witherod, Viburnum cassinoides
*Northern Arrowwood, Viburnum dentatum
Nannyberry, Viburnum lentago

Perennials and Herbaceous Plants
Northern Maidenhair Fern, Adiantum pedatum
*Jack-in-the-pulpit, Arisaema triphyllum
*Wild Columbine, Aquilegia canadensis
*Bushy Aster, Aster dumosus
*Heath Aster, Aster ericoides
New England Aster, Aster novae-angliae
Dwarf Cornel, Cornus Canadensis
Glade-fern, Deparia acrostichoides
Tufted Hair Grass, Deschampsia cespitosa
Carolina Lovegrass, Eragrostis pectinacea
*Sweet Joe-Pye Weed, Eupatorium purpureum
*Grass-leaved Goldenrod, Euthamia graminifolia and Euthamia tenuifolia
Wintergreen, Gaultheria procumbens
Interrupted Fern, Osmunda claytoniana
Switchgrass, Panicum virgatum
*Torrey’s Mountain Mint, Pycnanthemum verticillatum
*Virginia Mountain Mint, Pycnanthemum virginianum
*Rough Goldenrod, Solidago rugosa
New York Fern, Thelypteris noveboracensis

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The information in this list is adapted from the following sources:

Vascular Flora of Rhode Island: A List of Native and Naturalized Plants. Lisa L. Gould, Richard W. Enser, Richard E. Champlin, and Irene H. Stuckey. Rhode Island Natural History Survey.

Sustainable Trees and Shrubs. University of Rhode Island Cooperative Extension Landscape Horticulture Program. GreenShare. Third Edition, 1999.

Planting Design Suggestions. University of Connecticut. Middlesex County Cooperative Extension Center. 2002.

Visit our demonstration rain garden at the North Kingstown Town Hall.

View our brochure about the garden.

How to plan, install, maintain - additional resources