A rain garden is a shallow depression that is designed to capture and filter rainwater runoff from impervious surfaces like roofs, driveways, and lawns. They are planted with tough plants that thrive during brief periods of inundation as well as drought, providing attractive habitat for pollinators and other wildlife.
Rain Garden designed and installed by Master Rain Gardener Linda Prieskorn.
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Why do we need
Rain Gardens? Every time it rains, water runs off impervious surfaces (surfaces where water cannot soak in) like roofs or driveways. This runoff collects pollutants such as soil, fertilizer, chemicals, oil, garbage, and bacteria, before it enters storm drains. This untreated water flows directly into nearby waterways. The US EPA estimates that pollutants carried by rainwater runoff account for 70% of all water pollution. In the Greater Cincinnati region, the top pollutants in rivers and streams are sediment and nutrients. These are often brought in by excessive amounts of runoff, causing erosion along streambanks. Developed areas generate 20X more runoff than natural landscapes. |
How Do Rain
Gardens Work? During a rain event, runoff is directed into the rain garden via rain chains, rain barrel overflow, downspouts, curb cuts, sheet flow, and other routes.
Water collects in the basin, rather than in a storm drain, allowing it to slowly get absorbed by the soil and plants. Deep-rooted plants help break up hard soils and create channels for water to move through. Rain gardens can even be built in clay soil. Plant uptake, physical filtration, and biological processes reduce contaminants like oil, metals, and nutrients. |
What are the benefits
of a Rain Garden? With less stormwater ending up in our waterways, localized flooding and erosion decrease. Compared to a conventional lawn, rain gardens allow for 30% more water to soak into the ground.
Plants and soils help absorb and filter pollution. Rain gardens are effective in removing up to 90% of nutrients and chemicals and up to 80% of sediments from the rainwater runoff. Rain gardens can beautify your landscape throughout the year, while also providing important habitat and food sources for pollinators and other wildlife such as birds, butterflies, and bees. |
"Rain Gardens Explained in 2 Minutes"
A Video by Alberta Low Impact Development Partnership
A Video by Alberta Low Impact Development Partnership
Rain Garden FAQ's
- Is a rain garden a pond? Rain gardens are not water gardens, ponds, or wetlands. In fact, they are dry most of the time, only holding water during and immediately after a rainfall event.
- Will it attract mosquitoes? Because rain gardens drain within 12-48 hours, they prevent the breeding of mosquitoes.
- Will it cause flooding in my yard or basement? No, an appropriately sized and placed rain garden will actually reduce flooding by capturing excess water. We recommend placing rain gardens at least 10 feet from any foundation, and always ensure the slope is away from buildings.
- How big does a rain garden need to be to work? The size of your rain garden is dependent on the size of its watershed, or the area that drains into it. For small areas like rooftops and driveways, you can roughly estimate 1/4 the drainage area to be the rain garden size. You will learn to calculate your ideal size in the MRG course. If you have limited space, a rain garden of any size will still have a positive impact.
- How much does it cost? Cost can vary widely (a few hundred to a few thousand) depending on the size of your rain garden and your patience. If you are patient, you can buy fewer and smaller sized plants and wait for them to fill in. You can even source extras from friends and neighbors for free. Mulch, garden borders, and soil amendments are other things to take into consideration. Compost can sometimes be obtained for free, or made on your own.
- How much maintenance does it need? Rain gardens require some work to install due to the nature of their shape, more digging and grading is required than a typical garden. They can certainly be designed to be low maintenance once your plants are established. By choosing the right plants, planting them close together, and mulching annually, it could take as little as 15 minutes a month during summer.
- Do rain gardens work in the winter? Yes, water will still soak into the soil in your garden while your plants are dormant. You can even pile snow around (not in) your rain garden, so when it melts in the spring, the snowmelt runs right into your garden. Do not pile snow with a lot of salt by your garden, unless you have salt tolerant plants.
- Can a rain garden be installed in clay soils? Yes, rain gardens can be installed in almost any soil type. Soil amendments like compost (never add sand in clay soils) can be added during the digging process to improve drainage, and plants should be selected with your soil type in mind.
