Rain gardens support the environment by mimicking systems in nature

Rain gardens support the environment by mimicking systems in nature

Rain gardens support the environment by mimicking systems in nature

By Jaime Clifton-Ross, Communications and Outreach Curator, National Environmental Treasure

Rain gardens support the environment, local biodiversity and mitigate the effects of stormwater runoff by mimicking systems in nature.

After a rainfall, water is often absorbed by soil where it hydrates plants or trickles into underground aquifers. But it’s a different story in urban areas. Large parts of the planet are covered in concrete, asphalt and other impervious surfaces (aka, materials that don’t absorb liquid). With very little exposed soil, water that runs off roads, parking lots, sidewalks and roofs called stormwater, can damage city infrastructure and flood neighbourhoods.

What’s more, as water rushes towards storm drains, it picks up various urban pollutants like oil, pesticides and other contaminants, which pollute waterways and cause ecological degradation in aquatic ecosystems. Agriculture also strains the earth’s natural systems. Converting forests and grasslands to farmland causes erosion since many different crop types cannot hold topsoil in place as effectively as native vegetation. As a result, stormwater can carry away fertile and vital topsoil. But solutions inspired by nature can help mitigate the negative effects of stormwater runoff while also supporting local biodiversity.

Rain garden with plants, soil, rocks and stones
Photo by martiweil from Getty Images/Canva

What are rain gardens?

One such solution is rain gardens. Considered a nature-based solution (also called natural climate solutions), this blue-green infrastructure functions in much the same way as a forest ecosystem. As sunken spaces made up of native plants, rocks and specialized soil containing organics, sand and mulch, rain gardens are designed to mimic the systems taking place in nature. As water runs off nearby parking lots and roads, rain gardens slow and absorb water flow. With the help of plants, they even filter out pollutants. They’re essentially traps that reuse and optimize rainwater.

How do rain gardens support the environment?

Rain gardens are fantastic blue-green infrastructure that tackle many environmental issues. They can host a cornucopia of native plants that attract pollinators and provide habitat and food for insects, birds, and other wildlife. They also help recharge aquifers, which are bodies of rock or sediment that hold and filter water underground. Aquifers are an important source of drinking water and are used for many domestic, industrial and agricultural purposes. Rain gardens even help mitigate the effects of climate change by enhancing soil health, which is an important and undervalued carbon sink.

Rain garden poster
Photo via Washington State University (free download) by Good Nature Publishing, 2016 artwork by John C. Pitcher.

Rain gardens are perfect in your yard

Because rain gardens can be built on a smaller scale, they’re a perfect addition to almost any yard. Not only do they help redirect water drained from roofs, but they also help irrigate soil and plant beds while enhancing backyard beauty and biodiversity. One way provinces can encourage homeowners to build rain gardens or even install rain barrels is to offer rebate programs. A successful example is the RiverSmart Homes Program in Washington, D.C. To reduce stormwater runoff and the level of pollutants entering waterways, the state offered rebates to homeowners who installed landscaping structures that reduced and/or cleaned stormwater runoff including rain gardens and rain barrels. Homeowners received a rebate based on the surface area of rain gardens at a rate of $3.00 US per square foot and a maximum rebate of $2,200 US.

False Lily of the Valley with rain drops and insect
False Lily of the Valley. Henrik_L from Getty Images.

How do you build a rain garden?

Building a rain garden is relatively straightforward, but there are a few things to consider. Check out the Old Farmer’s Almanac, the City of Edmonton and the Capital Regional District’s resources for detailed guides on how to build rain gardens. But to get you started, here are few tips:

– Ensure your rain garden bed is 20% to 30% the size of your roof, driveway or whichever impermeable surface is your water source.

– Select a dry area that is 10 feet away from the foundation of your house. Ensure it’s not already saturated with water and that it’s slightly downhill from your drain.

– After digging a rounded basin, fill it with the Farmer’s Almanac’s soil formula of “one-half sand, one-quarter compost, and one-quarter topsoil” for optimal draining. 

– Select native plants that are suited to your region and species that can thrive in the different conditions in your rain garden. The Old Farmer’s Almanac explains how to choose the right plants for your rain garden depending on sun exposure and shading.

– Keep in mind that different species of plants do different things. For example, tall trees and shrubs deflect water and slow it down. Tall grasses absorb water, filter it and suck up pollutants. And shorter, well-rooted plants hold soil in place and direct the flow of water.

Happy rain gardening!