A rain garden can capture rain that would otherwise flow down your lawn and driveway into streets and storm sewers, and use it to make your property more beautiful. It does this if it is located where rain can be directed into it, built so that it can temporarily hold the water (a rain garden is not a pond), and planted with appropriate plants to add beauty and attract birds, bees and butterflies. While a handy homeowner can
create a nice rain garden, assistance of a landscape professional with experience in rain gardens can be very helpful.
As in real estate, the first three things are location, location and location. The rain garden should be at least 10 feet from buildings. If one of your downspouts drains into your lawn, perhaps you already know where your rain garden should go. If it instead drains onto the driveway, could it be redirected toward a section of the yard?
Does the soil in that section drain readily? Dig a wide hole 6 inches deep and fill it with water. Wait 24 hours. If the water disappears within that time, the location is suitable for a rain garden.
Can you carve out a large enough space to handle the amount of rain you will get during downpours? Rain gardens range from 100-300 square feet and can usually handle rain from hard surfaces (roof, driveway) three times their size. More than one rain garden may be needed to handle rain from larger areas. Use a hose or rope to outline a curved shape for the proposed garden and move it around until you are satisfied with its placement.
Unless it is located in a depression, you will have to excavate between 4-10 inches to form the level bowl of the rain garden. If the site is not level, use some of the excavated soil to make a berm on the downslope side to further prevent overflow. You may also wish to add a border.
Next comes the fun part – planting. Rain gardens can be located in sun or part shade. They have distinct planting areas: the bowl and the upper part and a transition zone between them. The bowl area will need plants such as spiderwort and blue flag that can handle wet feet. Plants for the entire rain garden should also handle dry conditions. Native plants are often preferred for that reason. You can use perennials, shrubs or even small trees in a rain garden. Don’t forget mulch. Choose wood chips made from hardwoods that will not float away. River rock can be used for the inlet.
Mulch will help keep down weeds but you will have to weed, especially the first season. You will have to water your rain garden in dry seasons. The final result is a beautiful garden that captures rain that would otherwise overburden storm sewers and water treatment plants. Step-by-step instructions are at: http://learningstore.uwex.edu/assets/pdfs/GWQ037.pdf
The Anoka County Master Gardeners invite you to visit our web page http://anokamastergardeners.org/. Click on “hot topics” for information about the Home Landscaping and Garden Fair, April 12, 8 a.m. to 3:30 p.m. at Bunker Hills Activities Center, 550 Bunker Lake Blvd. NW, Andover. There also is information on our plant sale (hundreds of plants at reasonable prices) and the plant diagnostic clinic, which offers expert help with your landscape and garden problems.
Lynda Ellis is an Anoka County Master Gardener.