How to Build a Rain Garden for Catching Rainwater
Rain Gardens Naturally Filter Storm Water Runoff
A well designed rain garden is an organic and low-tech method for controlling the run-off from rainstorms and snow melt. Water runoff from rooftops, driveways, patios and other nonporous surfaces is channeled and directed away from buildings and towards a low-lying section of the yard. As the rainwater and snowmelt runoff travels across the lawn and hardscape, fertilizers and pollutants are washed into the rain garden's natural filtration and cleansing system.
Dug into a shallow bowl shape, the rain garden retains storm water run-off and helps to control soil erosion. The sunken planting beds capture the run-off and hydrate the landscape plants, and any excess water filters down through the soil. The organic cleansing action helps to remove salts and chemical residues before the rainwater seeps deep below the surface into the underground aquifers.
The lead photo was taken in early summer and highlights the native ferns that dominate our rain garden. Other perennials including Brown-Eyed Susan and Ajuga Bugle plants add colorful blooms, while an Inkberry shrub and a dwarf conifer provide texture and visual interest during the winter season.
Rain gardens are easy to maintain and can attract birds, butterflies, toads and other wildlife into the backyard. Here's a few tips on how to make a rain garden.
How to Make a Rain Garden
Locating the Rain Garden
Our property is situated on a hillside, and we get a lot of storm water runoff and snowmelt from the surrounding higher elevations and from the rooftop of our home. This photo shows our rain garden in late winter, after this year's snowmelt is gone and before the perennial plants have awoken from their winter slumber.
Located in the lowest section of the backyard, we dug the rain garden into the bottom of the sloping lawn and directly in front of a berm that forms one side of our little pond. We buried a plastic drain pipe under the lawn and connected the other end of the pipe to the primary downspout for delivering runoff from the roof. A gentle swale sculpted into the lawn steers more water run-off from rainstorms and snowmelt away from house and into the rain garden.
Note: the Rain Garden is separated from the pond by a berm of soil. Do not let water run-off drain into your koi pond!
We used pieces of fieldstone and rock to create a border and to define the edges around the rain garden. The fieldstone also helps to disguise and protect the plastic drain pipe. A few strategically placed rocks in front of the drain pipe opening helps to diffuse the rushing water as it travels downhill from the roof and into the sunken garden. We do not apply any mulch, which would likely wash away from the drainpipe area and into the basin of the planting bed. Instead, a ground cover of Ajuga Bugle plants helps to control weeds.
Between rainstorms, the opening to the drain pipe and its surrounding rock cave is a favorite hangout for a large toad, who is a very welcomed visitor to the rain garden. Other visitors include insects, wood frogs, chipmunks, garter snakes and an occasional box turtle.
Our rain garden fits well into our landscape, is simple to maintain, looks good and is very effective at controlling large volumes of run-off from the roof and the sloped yard. Planted primarily with native Christmas ferns and Cinnamon ferns, the plants help to control soil erosion on our hillside and act as a natural filter. The captured storm water run-off soaks the soil and provides plenty of moisture for the ferns before the excess water seeps down into the ground. The water run-off is utilized by the plants rather than washing away into a storm drain.
Even after a significant rainstorm, the planting bed and rain garden dries out within a day and does not leave any standing water .
Rain Gardens Do Not Attract Mosquitoes!
The Benefits of Creating a Rain Garden Include:
- Controlling storm water runoff and reducing soil erosion
- Reducing the amount of runoff that enters the storm drains and municipal water treatment systems
- Protecting rivers and stream from property runoff that contains fertilizers, pesticides and other chemical pollutants
- Filters storm water runoff while replenishing groundwater and aquifer reserves
- Attracts birds, butterflies and other wildlife
- Reduces lawn and gardening maintance
Tips for Creating a Rain Garden
- Select a low-lying area or natural depression as the site to create your new rain garden. Consider using an area that puddles naturally after a rainstorm or snowmelt.
- Strategically locate your rain garden near a downspout or at the bottom of a natural slope, but position the planting bed at least 10 feet away from the house foundation and other buildings.
- Do not locate your rain garden over the septic tank or leeching field.
- Avoid digging in areas near underground utilities including gas, electrical and water lines. If in doubt, check your local listings for the "Call Before You Dig" contact information.
- Use hardy native plants that are suitable for planting in both wet and dry conditions. Add a few non-native plants for seasonal variety of height, foliage, texture and blooms. Avoid planting exotic and invasive species.
- Until the rain garden plants become established, weed the planting bed often to remove the undesirable weeds. The established and matured perennials will crowd out the weeds, reducing the long-term maintenance needed to keep the rain garden looking good.
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Rain Garden at the University of Nebraska
Rain Chains & Rain Barrels
50-Gallon Rain Water Collection Barrel with Brass Spigot
Consider a Rain Barrel
Rain barrels are another option for controlling storm water runoff. Unlike a rain garden that uses the trapped water immediately to hydrate thirsty plants, a rain barrel collects and stores the rainwater for future use. Rainwater from the roof is channeled through the gutter and downspout to an inflow point at the top of the barrel. When the barrel is full, an overflow value allows the excess water to escape. A spigot at the bottom of the rain barrel connects to a garden hose, making it easy to use the rainwater when and where it is needed.
Most rain barrels are essentially large plastic containers. Manufactured kits are easy to install, and are available in a variety of styles ranging from basic utilitarian to decorator models. Size and capacity also varies; 50 to 75 gallon storage capacity rain barrels are commonly available. If more watering capacity is needed, some models can be hooked together through a simple manifold system that delivers rainwater to each of connected barrels.
The USDA Plant Hardiness Zone Map
The USDA Plant Hardiness Zone Map is now interactive: Search using your zip code or click on your state to find your exact plant hardiness zone for your area.
A common misconception about rain gardens: rain gardens are not swampy bogs. A well-designed rain garden controls and utilizes the flow of storm water, however a rain garden is not a bog and it does not stay wet all of the time (no standing water means no mosquitoes). Planted with native perennials, a typical rain garden drains well and dries out within a day or so, filtering the runoff before it enters into the groundwater system.