Gardeners can help protect and restore the Chesapeake Bay watershed region while also creating beautiful rain gardens.

The Chesapeake Bay is one of Maryland’s most valuable natural resources. It provides countless benefits to humans, animals, plants and the region’s economy. But adverse influences such as population growth, pollution and sediment runoff have all conspired to endanger the health of the bay.

Fortunately, gardeners can be part of the solution. By avoiding overuse and misuse of fertilizers and pesticides, and through utilizing sustainable garden practices, Marylanders — most of whom live within a half-mile of a drainage ditch, storm drain, stream or river — can improve water quality and conserve our natural resources for future generations. One way to be a “Bay-Wise” gardener is by installing a rain garden.

Here’s what you need to know:

What are rain gardens?

When it rains, water runs off impermeable surfaces such as roofs, driveways and lawns. That water contains pollutants such as motor oil, sediments and fertilizers, which can then enter and pollute local waterways. Rain gardens provide a safer place for contaminated water to go.

How do rain gardens work?

Constructed by digging a bowl-like depression about 3 to 4 inches below the lawn’s surface, a rain garden should be located strategically on a down-sloping area of your property, where it can collect as much rainwater runoff as possible.

Once collected, polluted water is gradually absorbed into the soil where it is naturally filtered and cleaned by vegetation and soil and can support the growth of plants and flowers. According to the nonprofit Groundwater Foundation, “Rain gardens are effective in removing up to 90 percent of nutrients and chemicals and up to 80 percent of sediments from the rainwater runoff. Compared to a conventional lawn, rain gardens allow for 30 percent more water to soak into the ground.”

How should I prepare my garden?

The dimensions of your rain garden will be based on the space available and the amount of polluted rainwater that is likely to drain from impervious surfaces into your garden. When digging your garden, be sure to excavate the existing sod, to minimize weed seeds. If the soil has a great deal of clay, you will need to add compost, sand and gravel to aid with water infiltration.

As with a traditional garden, decisions about plant and flower choices will be a function of your soil type and pH, light conditions, sun to shade levels and border design.

What should I plant?

Rain gardens should always contain native plants. Plants that are indigenous to the Chesapeake Bay watershed region can typically thrive without chemical fertilization or pesticides. Generally, they require minimal maintenance and can absorb large amounts of water.

Black Eyed Susan
The Black Eyed Susan is not only the state flower, but a native plant. (File photo)

Some suggestions for native and pollinator-friendly perennials, shrubs and trees likely to thrive in a rain garden include Switchgrass (Panicum virgatum); Butterfly milk weed (Asclepias tuberosa); Black-eyed Susan (Rudbeckia hirta); Cardinal flower (Lobelia cardinalis); Rose mallow (Hibiscus moschetos); Bergamot (Monarda bradburiana); Blue flag iris (Iris versicolor); Blueberry (Vaccinium corymbosum); Inkberry (Ilex glabra); and Eastern redbud (Cercis canadensis). These species are readily available at many nurseries in our area.

Don’t forget to weed, mulch and water during dry periods!

For information on rain gardens and the University of Maryland “Bay-Wise” program, visit extension.umd.edu/ baywise.

Rebecca Brown began her career as a horticulturist more than 25 years ago and studied at the New York Botanical Gardens. She has been a University of Maryland, Baltimore County master gardener for five years and is a backyard beekeeper.

Norman Cohen is a retired chemist. He has been gardening for 38 years and has been a University of Maryland, Baltimore County master gardener for 10 years. Cohen also provides gardening education to the public at local farmers markets.