By Karna Berg, Master Gardener
Gardens differ in the conditions they provide for plants. The gardens in your yard may be set in predominantly sun or shade and the soil may be clay or sand, wet or dry. Consider the soil conditions in your yard. If you have a naturally wet area, you may want to build a rain garden. A rain garden is an area of land planted with suitable (often “native”) plants that replaces existing lawn.
Why a rain garden? A rain garden can help clean the water that moves through your landscape. It soaks up stormwater from roofs and other surfaces in your yard. During a rainstorm, the rain garden fills with a few inches of water and allows the water to slowly filter into the ground instead of running off to storm drains. It allows 30 percent more water to soak into the ground than a conventional lawn. A rain garden filters pollutants that would otherwise empty into the storm drains. In this way, rain gardens benefit the environment and they also provide a beneficial wildlife habitat.
Where might you build a rain garden in your yard? You do not want to choose a spot with standing water. A rain garden is not intended to be a wetland or a water garden with permanent water. The goal is to have an area where the water can soak into the ground. Rain gardens are designed so that water soaks into the ground in approximately one day.
To build a rain garden, you will create an area that can catch water from your yard, perhaps from a down spout or just from the natural slope of you yard. It should not be too close to the foundation of your house, instead at least ten feet away from it. You will need to remove the sod and make a shallow depression. It doesn’t need to be very deep. About six inches is sufficient. You will probably want to amend the soil in the garden. A good mix for a rain garden is one-half sand, one fourth compost, and one fourth topsoil.
Then comes the fun part, selecting the plants for your garden. Like any garden, put taller plants in the center and work out from there. For sun, some good choices are coneflowers, blue flag iris, Joe Pyeweed (there are now miniatures of this plant), astilbes, daylilies and bee balm. For shade, consider turtlehead, meadow rue, wild columbine, coral bells and foam flowers. Often, gardeners will choose native plants for a rain garden but that is up to you.
Most counties and some towns offer grants to help with the cost of building a rain garden. Classes on how to build a rain garden are taught by MN extension or county employees. These classes will help you decide where to build it and the correct size needed to absorb the rain from a roof or driveway. This link explains how and where Dakota County residents can get help in designing and building a rain garden.
So, have fun with a new garden for your yard that you will enjoy along with the birds, bees and other wildlife.