The buzzword of the day lately must be “rain garden”. I hear this word constantly. Knowing nothing about them, and having my curiosity piqued, I decided to do some research. Typical first place to start: Google. Result: A plethora of information ranging from a definition, to how-to build one, to the benefits of having one. Allow me a moment to share this fascinating discovery with you.

A rain garden is a planted depression that is designed to take the excess rainwater run-off from a house or building and its associated landscape. The plants are a selection of wetland edge vegetation that absorb the water, and through a process of transpiration, return water vapor into the atmosphere. For those of you looking for a new vocab word, Wikipedia offers this: “Transpiration is the evaporation of water from aerial parts of plants, especially leaves, but also stems, flowers, and fruits. Transpiration is a side effect of the plant needing to open its stomata in order to obtain carbon dioxide gas from the air for photosynthesis.”

When an area becomes developed, the natural groundwater filtering process is disturbed and water run-off from roofs and roads is not absorbed into the ground properly. Think of this like a rock skipping across a pond indefinitely, only in this case, it’s water skipping over ground. Flash flooding, erosion, and stress on our municipal stormwater system can result. This also means that our lawns and gardens are not receiving the full benefit of the rain water.

A solution to this problem could be to create a rain garden or rain barrel, both typically located near a drain pipe from a roof. Whereas a rain barrel simply provides storage for water run-off that can be used at a later time for lawn and garden watering, a rain garden actually provides an area for water to be absorbed and filtered down into the ground (without causing puddles).

And, because water is absorbed fairly quickly by the vegetation, rain gardens do not provide breeding grounds for mosquitoes. Other benefits are that pollutants are filtered, drought effects are lessened, the need for irrigation is reduced, and these plantings encourage wildlife and biodiversity.

Soil in a rain garden should be permeable enough to allow water to drain and filter properly, typically containing 60% sand, 20% compost, and 20% topsoil. Before digging an area for the rain garden, you may want to calculate the size garden you will need, although any size garden will be a good start. For those of us who are technically-minded, take the roof square footage and multiply by 623, then divide the product by 1,000, then multiply the result by the average number of annual inches of rainfall at your location. Average annual rainfall in Bennington is 35.74 inches. Locate the garden at least ten feet from your house to avoid moisture problems in the basement. The garden should be about six inches lower than the surrounding ground level.

Select native plants that can tolerate both saturated and dry soil, and steer clear of invasive species. Brooklyn Botanic Garden online has a list of good rain garden plants specific to each region; including ferns, bee balm, grasses, shrubs, and wildflowers. Add three inches of hardwood mulch around plants to suppress weeds and absorb heavy metals. Maintaining the garden should be nothing more than simply weeding as the plants grow.

By Lissa Stark