Stormwater, planted basins, runoff, native plants, soil media, infiltration, pollution filtering, curb cuts, downspouts, maintenance, and green infrastructure
Rain gardens
Rain gardens are shallow planted areas that collect runoff from roofs, streets, driveways, and other hard surfaces. They slow water down, let some of it soak into the ground, and use soil and plants to filter pollutants before the water reaches drains, streams, or lakes.
What rain gardens are
A rain garden is a shallow landscaped basin designed to receive stormwater runoff. It is not simply a low spot that stays wet all the time. A well-designed rain garden fills during rain, drains within a reasonable time, and supports plants that can handle both wet and dry conditions.
How they work
Runoff flows into the garden from a downspout, curb opening, driveway, path, or other hard surface. The basin temporarily stores water, spreads it across planted soil, and lets it soak through mulch, roots, soil, and sometimes gravel or engineered media. Overflow paths handle storms that are larger than the garden can hold.
What they filter
Rain gardens can capture sediment and help reduce some nutrients, metals, oils, and other pollutants carried by runoff. Plants, soil particles, microbes, and organic matter all play a role. They do not make polluted water perfectly clean, but they can reduce the amount and speed of dirty runoff entering drainage systems.
Where they fit
Rain gardens can work in yards, schools, parks, parking-lot edges, sidewalk bump-outs, and street rights-of-way. They are most useful where runoff from hard surfaces can be directed safely into a planted area. They should be placed with care around building foundations, septic systems, utilities, steep slopes, and contaminated soils.
Plants and soil
Good plant choices depend on climate, sun, soil, salt exposure, and how long water will stand after storms. Many guides recommend regionally appropriate native plants because they can support local insects and wildlife. The soil must drain well enough to avoid long ponding while still holding moisture and filtering runoff.
Sizing and design
Designers estimate the drainage area, soil infiltration rate, garden depth, and expected storm size. A small home garden may handle roof runoff from one downspout, while a street rain garden may include curb cuts, underdrains, overflow structures, and engineered soil. The inlet needs erosion protection so fast water does not wash mulch away.
Care and limits
Rain gardens need weeding, mulch care, plant replacement, sediment removal, and checks after large storms. They are not ponds, mosquito habitats, or a cure for every flooding problem. If water remains for too long, the site may need better soil, an underdrain, a smaller drainage area, or a different stormwater practice.
Why it matters
As cities add roofs and pavement, rainfall moves faster into drains and waterways. Rain gardens help return some of that water to a slower, more natural path. They also make stormwater visible, add habitat and shade, and give neighborhoods a practical way to reduce local runoff when they are planned and maintained well.