Rain Gardens

Stormwater Runoff	Benefits	Design and Installation	Choosing the Right Plants
Costs	Maintenance	Credits and Source Materials	Plant Lists for Rhode Island

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, like driveways and walkways, around your home.
  
• 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.

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

Stormwater Runoff
In addition to adding beauty to your home landscape, rain gardens can also help protect water quality by reducing stormwater runoff from your home 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

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

• 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 and creative landscaping designs.
  
• Reduce storm drain overload and flooding if adopted on a community or neighborhood scale.
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Design and Installation
There are different methods for designing and sizing your rain garden. You can get the details of these methods on the Healthy Landscapes website.

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. Here are some guidelines to follow:

• The rain garden should be at least ten feet from the house so infiltrating water doesn’t seep into the foundation.
  
• Do not place the rain garden directly over a septic system or near wells and underground utilities.
  
• 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 the 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 your plants as well as for mosquito concerns.
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Choosing the Right Plants
It is best to use native, non-invasive species that are resistant to the stress from 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 from 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. There is a list of suggested plants on the Healthy Landscapes website.
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Costs
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 types of plants you choose, 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 plants you use.
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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. Some weeding may also be necessary the first year until the plants fill out and can compete with 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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Credits and Source Materials
The above information is from the Healthy Landscapes Factsheet which is adapted from the following sources:’

Rain Gardens : A How-to Manual for Homeowners . Roger Bannerman and Ellen Considine. http://clean-water.uwex.edu/pubs/raingarden/rgmanual.pdf

Community Watersheds: Educating Watershed Constituents. Center for Watershed Protection.
http://www.cwp.org/Community_Watersheds/educating_constituents.htm

Creating a Rain Garden in Your Yard. Town of Maplewood , Minnesota.
http://www.ci.maplewood.mn.us
Click on nature center then demonstration gardens.

Special thanks to the following people for their information and review of the Healthy Landscapes Factsheet: Dr. Brian Maynard, URI Department of Plant Sciences; Roseanne Sherry, URI Master Gardener Coordinator; and Lisa Gould, Rhode Island Natural History Survey, College of the Environment and Life Sciences.
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Plant Lists for Rhode Island
These lists include plants that can tolerate temporary pooling of rainwater as well as dry periods. Most of the plants are native species, although some may not be readily available at all garden centers. You can contact the Rhode Island Wild Plant Society (www.riwps.org or 401-783-5895) for more information about native plant sources.

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 (Adiatum 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; E. 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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