Rain Gardens

Rain gardens reduce pollution caused by stormwater. Planted with shrubs and perennials, upkeep is simple and inexpensive. By creating a rain garden you put stormwater into the ground and keep dirty runoff from harming streams, ponds and water supplies.

Picture from EPA Green Infrastructure Website

Rain Garden picture from EPA Green Infrastructure Website

Read more to learn how to plan and build a rain garden for your yard.

First, look at your yard in the rain to see where storm runoff goes and where to build the rain garden. You can capture stormwater from roof downspouts and/or runoff from your driveway. Make sure the rain garden is 10 ft away from your house foundation, 15 ft away from septic system, and 25 ft away from a private well water supply. The overall size can vary, but is likely to require about 2 square feet of rain garden for every 10 sq ft of runoff area. For more details, download a guidebook by the University of Rhode Island (http://www.uri.edu/ce/healthylandscapes/raingarden.htm#design ).

*A Reminder: Before you dig, phone 1-800-DigSafe to learn where underground pipes and wires are located.

Second, redirect runoff from roof downspouts, the driveway or other impervious area so the water can flow into the rain garden site. If you are making a garden with a concentrated inlet (e.g. from a pipe), gravel should be used to prevent erosion where the runoff enters the site.

Overall you have a lot of options in your landscape design, as long as you take into consideration your soil types and the slope of the surrounding terrain. Rain gardens can be built on uneven terrain by the addition of low berms.

Rain Garden picture taken from the Massachusetts Watershed Coalition Rain Garden Guide

Rain Garden picture taken from the Massachusetts Watershed Coalition Rain Garden Guide

Normal rain gardens will need to be dug 12 inches deep to allow for a 6-9 inch basin in the middle and for 3 inches of mulch cover  (for sandy or loamy soils).

Slow draining or heavy clay soils need to be dug 2-3 ft. deep and refilled with a soil mix of 50% sand, 30% compost, and 20% loam. The important part of a rain garden is to make sure you have proper drainage so that the plants can help filter the runoff.

Note: If groundwater seeps into the bottom of the excavation, find another place to build your rain garden.

Third, identify plants that work best for your garden. Native species are ideal because these thrive in local soil and climate conditions, so supplementary fertilizer and water is not needed. The plants are going to need to handle extremely wet to drier conditions. The University of Connecticut has a wonderful design guide for rain gardens and a handy database to help with you selection of plants. I have linked the site here for your convenience:  http://nemo.uconn.edu/raingardens/plants.php .

Overall, the cost of construction of a rain garden will vary. Depending on materials the cost can range from $2 per square foot for do-it-yourself to $10 per square foot for hired help. A home rain garden is usually about 100 to 200 square feet and cost between $200 to $2000 depending on what you feel is needed to complete your garden.

The Massachusetts Watershed Coalition has published an easy-to-use Rain GardenGuide (www.commonwaters.org/images/stories/pdfs/raingardn_gde.pdf). It reiterates some points above, has more details on how to plan a rain garden, and has pictures to help you visualize your outcome, a beautiful rain garden.


One thought on “Rain Gardens

  1. Pingback: Grange Special Event: Creating a Rain Garden | Essex on Lake Champlain

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