Now that the spring floods have slowed to refreshing showers and garden soils are drying to workable conditions, many gardeners are repairing the damage that 6-plus inches of rain have caused. Building a rain garden may be the answer to minimizing flooding and slowing erosion in the backyard. Here is what you need to know about this new twist on an old concept and how to build your own rain garden:
Rain gardens are quickly becoming one of the most popular perennial garden designs. If constructed correctly, they catch rainwater and slowly allow it to filter into the ground. Recharging groundwater and minimizing surface water runoff, rain gardens are key to cutting down on soil erosion and keeping creeks, streams and lakes clean and pure.
But function can lead to fashion. Often planted with native wetland and prairie wildflowers and grasses, they provide a beautiful array of colors, textures and style all season long. They also can attract birds, butterflies and dragonflies, leading to hours of viewing enjoyment.
Building a rain garden is easy but requires planning. Locate the garden in full sun at least 10 feet away from your house's foundation. Places that work best naturally tend to catch rain water as it runs off the house, street or drive. Using pre-existing low depressions makes digging easier. Avoid locating rain gardens in areas that tend to stay wet or do not drain. These areas may be better suited for a bog or wetland garden. A functioning rain garden will fill when it rains and will drain out in two or three days and be dry until the next rain. Dig the garden 4 inches to 6 inches deep with a flat, level bottom. The larger the bottom, the more area the water can drain through. Work the soil and add organic matter such as compost, leaf mulch or peat moss. Do not add fertilizers or animal manure as native plants tend not to like nutrient-rich soil. Weeds may be a problem the first year, but hand-pulling and hoeing will keep them under control. Likewise, apply a 2- to 3-inch layer of coarse, shredded hardwood mulch around plants the first year until the roots are able to get established.
There are many plants that will thrive in these growing conditions. Some of the more common ones are swamp milkweed, New England aster, Missouri sedge, spike rushes, cardinal flower, great blue lobelia, winged loosestrife, switchgrass, bulrushes, giant goldenrod, blue flag iris, false dragon's head, Spotted Joe-Pye weed, sneezeweed, prairie blazing star, wild bergamot, marsh phlox, stiff goldenrod and arrowhead.
Still have questions or want to learn more about building a rain garden? The Douglas County Extension Master Gardeners, in conjunction with the city of Lawrence, will be host to a one-day workshop titled "The One-Two-Threes of Building a Rain Garden." The seminar will be at 10 a.m. Saturday at the Douglas County Extension Center on the Douglas County 4-H Fairgrounds, 2110 Harper St. Instructors will use the two rain gardens constructed on site to demonstrate the principles and how-tos of basic rain garden design. The seminar is free and open to the public.