How planting a 'rain garden' could help protect your home from flooding

Heavy rains and flooding hit Spain's Catalonia region last week, claiming at least two lives and submerging homes and roads. ADVERTISEMENT ADVERTISEMENT Unfortunately, it’s not the first time. And it won’t be the last: scientists predict an increase in extreme weather events globally, fed in part by human-caused climate change. When the deluge subsides, people are left to deal with the devastation, shovelling sludge from streets and pumping floodwater from their living rooms. Gardens may be the last thing people fix, but could they become fortifications against future disasters? As the threat of flooding and droughts strengthens, so too does the argument for planting a 'rain garden'. What exactly is a rain garden? Simply put, a rain garden is a depressed bed planted with native perennials and shrubs selected for their high-water tolerance. It’s strategically situated in a spot where water – from downspouts, driveways, compacted soil and other sources of runoff – flows downward toward it. That runoff waters the plants and filters pollutants as the soil absorbs it. And it means the excess water, as well as the road sediment, debris, pet waste pathogens, fertilisers and chemicals it picks up along the way, is kept out of storm drains, watersheds and wetlands. Rain gardens can also stop water from entering your basement or affecting your foundation. In dry, drought-stricken regions, too, many gardeners are turning to rain gardens and other methods of collecting rainwater. How to create a rain garden You can make a rain garden as big or small as you like, but keep it at least three metres from your house, garage or other structures. Don’t plant it over a septic tank or underground utilities, or near a well that provides drinking water. And avoid sloped areas and those that are soggy to begin with. Dig the bed in your preferred size and shape (kidney, crescent, round and teardrop are popular). You can either gradually grade the soil toward the centre so it is 15 centimetres lower than the perimeter, or dig everything but the perimeter 15 centimetres deep so a berm that high surrounds the sunken bed. Direct water toward the bed by installing a gutter extension, creating a downhill slope, digging a trench or connecting a PVC pipe to a distant gutter and running it underground to the rain garden. Slow the flow of water by lining your trench or slope with rocks or small stones. Some gardeners prefer to keep the centre free of plants and cover the soil there with stones, as well. The best plantings for a rain garden Choose native plants best suited to high-water or, if planting the centre, even swampy conditions. Natives are naturally adapted to your region’s environment, so they’ll be easier to grow, require less maintenance and will also provide a habitat for bees, birds, butterflies and other wildlife. Consider planting flowering perennials alongside sedges and grasses, and incorporating shrubs and small trees, if space allows. Including some evergreens will further help avoid erosion. FloraVeg.EU is a good resource that lets you search for native vegetation by geographical region and other parameters. Put plants with the highest water needs at and around the centre of your rain garden, where water will collect and pool for a bit before seeping into the soil. Plant those with moderate water needs along the elevated perimeter of the bed, which will be somewhat drier. How to care for a rain garden In the absence of rain, water the plants as necessary throughout their first year, as their roots grow and anchor into the ground. Keep on top of weeds, too, until the plants grow and fill in the bare spots between them. After you’ve designed, graded and planted your rain garden, there won’t be very much for you to do, except sit back and enjoy your striking natural landscape – and its hidden ecological function.