By Marilyn Pribus –
“Each time it rains, pollutants such as nitrogen, phosphorus, zinc, and even lead flow directly into our sewers and waterways,” laments horticulturist Karyn Smith of Stanardsville.
Since much of the water in our area is drawn from the Rivanna River watershed which encompasses Charlottesville, all of Albemarle County and parts of Fluvanna and Greene Counties, it’s critical to protect our water sources.
Some of our local stormwater even makes its way to the Chesapeake Bay where pollution can affect wildlife from birds to fish and even oysters. Each little oyster can filter 50 gallons of water every day so it’s particularly important to protect them.
Smith observes that humans have covered all too much land with buildings, roads, parking lots, tennis courts and other impermeable surfaces. Fortunately, she continues, as more people become aware of runoff-caused pollution, they seek better ways of managing their property to protect the environment.
One good tactic is employing permeable pavers for walkways, driveways and even parking areas. This means that, instead of running off, much of the rain can soak through the pavers to the soil beneath and eventually into the groundwater.
Another step is to increase the natural areas in yards. More and more people are installing bio-retention areas on their property. That’s the technical name, but we think rain garden has a far more romantic sound.
How Rain Gardens Help
A rain garden is simply a planned depression inviting rainwater from roofs, driveways, and sidewalks to be absorbed gently into the ground. The addition of such a garden to your property will add charm and beauty while helping to reduce erosion, flooding and water pollution.
“Rain gardens capture runoff, slowing it down and allowing it to filter through the soil,” explains Smith. “This helps prevent the poisoning of our clean water by keeping the pollutants from entering our waterways.”
It’s estimated that a rain garden helps absorb as much as one-third more water than the same area of lawn. Other benefits include lessening the potential for home flooding, reducing standing water in your yard and—the distinctly positive side effect of eliminating spots for mosquitoes to breed.
In addition, it’s a way to attract birds, butterflies and beneficial insects that eliminate insect pests. And, once established, rain gardens are not only appealing, they reduce the time required for yard maintenance.
Five Easy Steps
- Choose a location at least ten feet away from building foundations, underground utilities or septic system drain fields. An ideal location might be a place that already collects water.
Contact local utilities if there is even a remote chance that you might hit service lines when you are digging. The agencies will check your property and spray paint or install little warning flags to protect your utilities.
- Determine if you have good drainage by digging a hole 6-8 inches deep and filling it with water. Measure the water’s depth, then measure again in an hour.
If it drains more slowly than one inch in an hour, you’ll need to add gravel at the bottom of your rain garden. A bed of at least six inches of gravel will ensure that you have good drainage and that your plants will not drown.
- Design your garden. It can be anything you like from a formal rectangle to freeform. Use a rope or hose to test various outlines, until it’s the size and shape you like.
- Prepare the soil. The ideal mix will include sand, topsoil and compost. Your local nursery or garden store can provide both guidance and soil amendments. Loosen up the garden area for a depth of about two feet. Grade it so the center is 6-8 inches lower than the sides, then make allowances for overflow in the event of heavy storms, possibly a dry “riverbed” of stones.
- Now the fun part! “Plants play a major role by absorbing pollutants and either holding them, or using them for nourishment and growth,” says Smith. ”There are hundreds of plants that are useful in rain gardens. Some of my favorites are Butterfly Bush, Virginia Sweetspire, and Crested Iris.”
You can employ trees, shrubs, flowers and groundcovers in any combination. Smith suggests that your best choices will be a variety of perennials native to this region because they already thrive in this climate, are generally less vulnerable to insect pests, and require less care.
Select plants that are tolerant of both wet and dry conditions. It’s a good idea to put plants that prefer drier soil at the edges and the ones that like “wet feet” at the lowest part of your garden. Especially consider varieties which attract bees, birds and butterflies.
Your new plants should receive water about every other day until they are growing steadily, then weekly until they are thriving. Once they are well established, they will probably only need watering during extended dry spells.
Virginia Cooperative Extension offers good regional guidance. Visit ext.vt.edu and search for “rain garden.” The Chesapeake Bay Foundation’s website cbf.org, also offers information on rain gardens and their value in protecting the Bay.
Marilyn Pribus and her husband live in Albemarle County near Charlottesville. They have kept a large flat area at the lowest point of their property completely natural. It serves as a natural rain garden attracting birds, butterflies and a resident box turtle.