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Rain gardens transform flooded backyards into green landscapes

Rain gardens help divert rainwater runoff away from a house’s basement and foundation.

Parklane Nurseries Limited

When retiree Karen Ho purchased her new build in Milton, Ont., she didn't realize the surrounding homes were on a slightly higher elevation; the first good rainfall was a real eye-opener. The compact suburban plot flooded, and when neighbours began landscaping – levelling and laying sod – it only made matters worse. The runoff from about 10 homes kept landing in her backyard, rendering it unusable.

Neither the City of Milton, nor the developer, offered solutions, so she turned to the Ontario Horticultural Association for help. They suggested she reach out to Sean James of Fern Ridge Landscaping. James, who has installed about 80 rain gardens throughout the Greater Toronto Area in the past seven years, encouraged her to turn her cookie-cutter yard into a rain garden.

That was four years ago. "Now, when it rains or when it's thawing in spring, I have a lovely pond in my front garden, full of native aquatic and marsh plants," Ho says. "The water is only there for a while – a few days – and then I don't have a pond any more, so there's no worries about mosquito eggs hatching."

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Her property now sports a footpath of crushed slate, gravel and river rocks that serve as both a walkway and a sort of dry riverbed that wicks the water down and into the temporary pond.

"In the early spring and late fall, I used to get dangerous patches of ice. … Now I can walk safely, and the path is quite beautiful. In the backyard, we didn't put in any grass, just native species of flowers, tall grasses and trees that can deal with the water that still trickles into my yard from all around," she says.

Along with runoff issues caused by development, homeowners are increasingly dealing with more climate-change caused extreme-weather events – deluges that lead to loss of life in the most extreme events, exact a financial toll as properties are submerged and a health toll as contaminants and bacteria are washed into our water supply.

In an effort to divert all of this runoff from basements and waterways, municipalities across the United States and Canada are offering incentive programs and enacting regulations to encourage homeowners to give up their putting-green lawns and go au naturel instead.

This year, for example, it will be mandatory in Toronto to disconnect downspouts. That water has to go somewhere. Earlier this month, Canada Blooms, the country's largest garden and flower show, featured rain gardens as a way to manage excess water on homeowners' property.

Most homeowners, especially gardeners, already understand the benefits of connecting their downspout to a rain barrel, but with sudden voluminous downpours, barrels can overflow within minutes. A rain garden not only has the ability to process whatever nature throws at it, it looks great doing so.

Rain gardens work by attracting and containing runoff, then drawing it down into the groundwater table. Planted with native flowers, grasses, shrubs and trees, in a somewhat sunken bed of loose, deep, absorbent soil, compost, sand and sometimes gravel, a rain garden collects, stores, utilizes and filters runoff and storm water before they can make their way into creeks, rivers and lakes, down a street sewer grate or into the nearest basement. In a typical yard, a rain garden may be situated near the source of runoff – the roof or driveway, but not too close to the foundation – or planted in a naturally low-lying spot on the property with the runoff diverted and carried through a pipe, either above or below ground.

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James has seen a shift away from manicured lawns, as customers become more interested in environmentally friendly landscaping that solves problems and creates habitat.

"We used to try hard to sell grassless landscapes and now people are coming to us requesting that specifically. Part of this seems to stem from a desire to be more eco-friendly and part of it is the slowly dawning recognition that, per square foot, gardens are lower maintenance than lawn," James says.

(Plus, he suspects the pesticide ban in Ontario has also helped guide people away from lawns since they can no longer be that perfect swath of green – "at least not without an awful lot of work.")

Stephen Spiteri also turned to James to address repeated flooding at his home that sits on a quiet cul de sac in Grimsby, Ont., in a huge natural trough between the Niagara Escarpment and Lake Ontario.

"We had two sump pumps running 24/7 just to keep water out of the basement. Once, during a rain storm, we lost power for 45 minutes and in that time, we had four inches of water in the basement," Spiteri recalls.

Since 2014, when rain gardens featuring river rock swales, berms and beds were created on about two-thirds of the property, the pumps have run only once and Spiteri has seen a substantial drop in his electricity bills.

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Spiteri's case required substantial work.

Generally, you don't need backhoes, special drainage pipes or a plumber's know-how to create a rain garden. Just a depression in the ground, some elbow grease and the right plant life.

"Because rain gardens experience alternate flooding and drought, plants need to tolerate both wet and dry conditions," says Jen Mayville, communications manager for Environmental Defence, who recently helped create a demonstration rain garden near Kew Beach, along Lake Ontario, in Toronto.

"Any combination of flowers, shrubs, grasses or ferns that meet these criteria will do well in a rain garden. Native plants are best because they are well suited to local growing conditions, and support local wildlife including birds and pollinators," she says.

Along with creating habitat in an urban setting, rain gardens can have a positive effect downstream, so to speak.

"Storm water – rain and melted snow – that runs off turf grass, roofs and pavement, carries with it contaminants and bacteria. This dirty water pollutes our waterways and beaches," says Brett Tryon, co-ordinator of Environmental Defence's Blue Flag program, an international eco-certification program for beaches and marinas.

With benefits extending from the basement to the beach, homeowners with an eye for savings and sustainability may want to incorporate this mitigation measure into their spring yardwork plan.

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