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North Kingstown Town Hall, May 2005. Visit our page
on the Demonstration Rain Garden at
the North Kingstown Town Hall. View our brochure about
the garden (click here for print version.)
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, and Lisa Gould, Rhode
Island Natural History Survey, College of the Environment and Life Sciences
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. 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 with creative landscaping designs.
• Reduce storm drain overload and flooding if adopted on a
community or neighborhood scale.
Designing and Installing a Rain Garden
There are different methods for designing and sizing your rain garden. See these
information
sources for details and instruction on rain garden creation:
Rain
Gardens in Connecticut: A Design Guide for Homeowners
UConn
Cooperative Extension System, links to website where .pdf manual
can be downloaded
Rain
Gardens: A How-to Manual for Homeowners. Roger Bannerman
and Ellen Considine. Click
here for a .pdf of this manual.
Landscapes
for Maine: Adding a Rain Garden to Your Landscape.
Community
Watersheds: Educating Watershed Constituents. Center for
Watershed Protection. http://www.cwp.org/Community_Watersheds/educating_constituents.htm.
Take
time to completely read through these references as your
first step to creating a rain garden. The sources describe
two different ways of designing and installing a rain
garden
and which 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 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 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.
The information in this factsheet is adapted from the following
sources:
Rain
Gardens: A How-to Manual for Homeowners. Roger Bannerman
and Ellen Considine. Click
here for a
.pdf of this manual.
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.
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.
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 at (401) 783-5895
or www.riwps.org for more information about native plant
sources.
Information about many of these plants can also be found
in the URI Cooperative Extension Sustainable Tree and Shrub
Manual, which is available on-line at http://www.pse.uri.edu/maynard_susplants/html_spl2000/index.htm or
call 874-2900 to purchase a copy. For additional ideas
on accenting with perennial and annual flowers, consult
the URI Cooperative Extension GreenShare Program Factsheet
Website, http://www.uri.edu/ce/factsheets/indices/0annperindex.html or
call the URI Master Gardener Hotline at 1 (800) 448-1011.
It is important to select plants that are native or sustainable,
non-invasive, and require little inputs of fertilizer,
pesticides and water.
* 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
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.
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