Heavy rainfall runoff can be detrimental to your home, your landscape, and the environment. A creative solution to that gully washer is to channel the water into a colorful rain garden. Here’s how to do it.
Why you may need a rain garden
Water pooling against your house can cause the foundation to become structurally unsound. Pooled in the yard, the water can oversaturate the grass and harm it. Standing water anywhere can be a breeding ground for mosquitoes. And stormwater that runs off into storm sewers carries pollution from lawns and streets into streams.
Creating a colorful solution
You can harness potentially destructive excess rainfall that flows from your downspouts or other areas of your property into an attractive landscape feature whose deep-rooted plants will help the water drain quickly. Take the following steps to create a rain garden:
- First, determine the best site for the rain garden. Position it to catch runoff from downspouts, driveways, or other areas of your yard where excess rainfall pools. Your rain garden should be at least 10 feet from your house and 50 feet from a septic system. Choose a spot that gets full sun.
- Before digging the garden, make sure the area drains sufficiently quickly to clear away water before the garden becomes a mosquito breeding ground. Sandy soil will drain relatively quickly, so your garden likely needs to be only a foot or so deep. If your soil contains slow-draining clay, you’ll need to dig a deeper area.
- To determine the proper size for your rain garden, consider the size of the roof or driveway you want to drain into the garden as well as the porosity of your soil. Your local extension office may be able to advise you on size. Rain gardens are typically at least 100 square feet. Even if your garden isn’t large enough to handle all the runoff, it will still be beneficial.
- Build a small berm on the lowest edge of the garden to prevent water from spilling out. You may need to cut an overflow path through it to route water to another garden or your lawn in the event of extremely heavy rainfall.
- You can funnel runoff into the rain garden in one of two ways. One is to install a French drain where the water exits a downspout, using a buried PVC conduit exiting from the French drain to the garden’s location. The other is to route the overflow into an open, shallow trench that empties into the garden. Line the trench with a layer of landscape plastic and cover with one- to two-inch landscape pebbles the entire way.
- When you dig the garden, remove the grass with a spade or a sod cutter, then dig the area to the appropriate depth with a shovel or excavator. Leave the bottom flat, and the sides gently sloped toward the center. Line the bottom and sides with landscape fabric, then cover with one-inch landscape rocks a few inches in depth. Top the rocks with a layer of gravel, then fill the garden with soil, leaving room on top for plants and mulch. Line the garden’s runoff area with rocks to prevent erosion.
- Native plants are the best choices for your rain garden because they develop deep root systems. Plant an eye-pleasing mix of shrubs, grasses and flowers in clumps of five to seven plants. Place the plants that are most water-loving in the center and plants that need little water along the edges. Add a three-inch layer of mulch.
Your rain garden will need watering until it is well established. When the first heavy rainfall comes, monitor how well the garden handles the surge of water. Make sure the water flows unrestricted into the garden from the downspout or other area you are draining. If water fills the garden to overflowing, you may need to expand your runoff area or the size of the garden.
Related – Growing a Meadow Garden