WHAT ARE RAIN GARDENS?
Rain gardens are easy to install, look good year-round, require little maintenance, and help prevent water pollution. Rain gardens are shallow depressions designed to soak up water and support trees, shrubs, and flowers that tolerate both wet and dry conditions. They are meant to capture runoff so that it can infiltrate into the soil. Planted with deeply rooted native plants, rain gardens do double duty, providing habitat and floral resources for pollinators while reducing storm surge in local watersheds.
Often located near gutter downspouts or places where water puddles, rain gardens can also be landscaped into gentle slopes or run curbside along streets. They are a win-win.
WHAT RAIN GARDENS ARE NOT!
Rain gardens are not ponds, and are not mosquito breeding grounds. Rain gardens should be designed to hold water for only a brief period of time after a storm, quickly infiltrating back into the ground. Unlike a pond or wetland, rain gardens should not generally be more than a foot deep at any given point and should not use any sort of liner. The actual depth and size of your rain garden will vary depending upon how much rainfall you need to collect from your roof or other impervious surface.
WHERE TO PUT A RAIN GARDEN
The rain garden should be located in a place that can collect as much impervious area (driveway, roof, sidewalks) runoff as possible. The best areas are generally where water naturally drains but doesn’t hold water. It should also be located at least 10′ to 15’ away from your home.
Do not place the rain garden directly over a septic system. It may be tempting to put the rain garden in a part of the yard where water already ponds. Don’t!
HOW BIOSWALES DIFFER FROM RAIN GARDENS
Although they sound similar, bioswales are designed to slow down rainwater through a curving or linear path, while rain gardens are designed to capture, store, and filtrate rainwater in a bowl shape.
Managing water with rain gardens and bioswales
HOW TO CREATE A RAIN GARDEN
First test the soil for texture and drainage. A good mix for a rain garden is 30% sand, 30–40% loamy topsoil and 30% organic material from yard waste compost. This mixture must be tilled into the existing soil to ensure proper drainage conditions. Fill a foot deep hole with water to test the drainage. If it doesn’t drain within 24 hours you will need to change location or soil.
FOR MORE DIRECTIONS
Environmental Protection Agency (EPA)
New Hampshire Water Group video