Valuable landscape amenity improves our waterways and reduces flooding
“And I wonder, still I wonder, who’ll stop the rain?” wrote Creedence Clearwater Revival’s John Fogerty. The question isn’t answered in his song, but there is a way for you to stop the rain.
Granted, you can’t keep drenching storms away. But by building a rain garden, you can stop rainwater from rushing directly into storm drains. A rain garden is a bowl-shaped area filled with porous soil and plants that tolerate wet and dry conditions. Rain gardens in private and public landscapes help to slow down the excess rainwater that runs off parking lots, roads, driveways, lawns and roofs. By giving water time to seep into the soil, rain gardens help to filter out pollutants and replenish the aquifer.
“Rain gardens are a fairly new concept in this region,” says Chris LaChance, WaterSmart Landscaping Program Coordinator with the Texas A&M AgriLife Extension Service and Texas Sea Grant. “They are a pretty standard practice in other parts of the country, including the Pacific Northwest, Michigan and the Northeast. Rain gardens are part of managing rainwater, or storm water, as we call it. The whole idea is that municipalities and individuals can play a role in the effort to manage the quality of the water released into our waterways.”
Clearer lakes, bayous and bay
Water from our watershed—including Clear Creek and Armand Bayou—all ends up in Galveston Bay. The bay and the estuaries around the bay are part of the local economy and quality of life. So any effort to protect the water quality helps to maintain a healthy bay for fishing, recreation, and tourism.
“Many people have the misconception that storm water goes somewhere and gets cleaned up,” says LaChance. “In developed areas, it doesn’t. Impervious surfaces like asphalt, concrete, roofing, and compacted soil prevent storm water from soaking in. So it goes directly from the storm drains into the nearest body of water—our bayous, lakes, rivers, and the bay. “
Impervious surfaces collect pollutants, and whenever it rains, those pollutants wash into storm drains. Pollutants can include oil, trash, sediment from construction sites, and chemicals like synthetic fertilizers and pesticides from treated lawns.
Rain gardens are a way for individual homeowners or commercial and public entities to manage storm water right where it falls, says LaChance. “A rain garden can capture runoff from a roof, sidewalk, parking lot or street. That’s important, because that ‘first flush’ of storm runoff contains the most pollutants. Particles in the soil can actually bind to some of the pollutants the water contains, and plants can even take up some toxic heavy metals without harm. Rain gardens can do a really good job of cleaning up the water before it reaches the bay.”
Excavate and let it percolate
“Not every yard is conducive to a rain garden—it needs a bit of a slope,” LaChance explains. Instead of a typical raised-bed garden, a rain garden is excavated to make a shallow depression. Water is directed downhill into the rain garden where it is allowed to sit for a while and soak into the soil.
LaChance offers guidelines for rain garden construction in presentations she gives to community groups, including homeowners’ associations. She has also helped to develop rain gardens in public spaces with the help of volunteers. She encourages residents to visit these for ideas. (See sidebar, “Visit a Local Garden.”)
The soil in rain gardens should be amended with porous materials for better water absorption and compost for nourishment. The best plant choices are native trees, shrubs and perennials. For the lowest point of the garden area, LaChance recommends plants typically found in wetland areas, which can withstand being inundated periodically. For the sides, choose plants that can handle having “wet feet” some of the time. Plants that can thrive in drier conditions can be planted around the edges. “When we use native plants, rain gardens can become wildlife habitats, attracting butterflies, hummingbirds and other birds,” she says.
And what about mosquitoes when you have standing water? “When designed properly, a rain garden will not have standing water for more than 24 to 48 hours,” LaChance says. “And the native plants will attract dragonflies, which are voracious mosquito eaters.”
Beyond their functional use, rain gardens can be an esthetically beautiful and valuable landscape amenity. So go ahead. Stop the rain for a while, beautify your yard, and protect the bay, all at the same time.
How will a rain garden help?
-It slows down storm water and lets it soak into the soil
-It filters storm water and therefore protects water quality
-It recharges ground water
-It is a beautiful landscape feature
Create Your Own WaterSmart Rain Garden
Tips from Chris LaChance, WaterSmart Landscaping Program Coordinator with the Texas A&M AgriLife Extension Service
The best time to plant any garden, including a rain garden, is in late fall so plants become acclimated before our dry, hot summers begin. Early spring would be the next good time. Like any new garden, a rain garden needs regular watering during the first two years to allow root systems adequate development.
Not every yard is suited for a rain garden. Storm water needs to flow through a rain garden. In a home landscape, there should be a slope no more than 12 percent or less than 4 percent. A low spot in the yard, that has standing water after rain, is better suited to be planted as a bog garden. Another choice for a rain garden location is capturing the overflow from a cistern as in the case of the rain gardens at ABNC and UH Clear Lake. In these situations, the slope is not that critical. A location in full sun is best—it allows for the greatest selection of flowering plants and water is able to evaporate and be absorbed more quickly. A rain garden should never be located near trees as tree roots could be damaged in the excavation.
Some of my favorite rain garden plants are: Louisiana Iris, Button Bush, Giant Coneflower, Spider and Crinum Lilies, and Texas Star Hibiscus.
Visit a Local Rain Garden
Armand Bayou Nature Center (at the Visitors’ Center)
8500 Bay Area Blvd.
Pasadena, Texas 77507
Butler Longhorn Museum and Heritage Park (behind the museum)
League City, Texas 77573
University of Houston-Clear Lake (near Entrance 3, in front of the Environmental Institute of Houston)
2700 Bay Area Blvd.,
Houston, Texas 77058
Claude Burgess Center
Deer Park, TX 77536
Chris LaChance, Program Coordinator
WaterSmart Landscapes for the Upper Texas Gulf Coast
Photos by Chris LaChance