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Wetland-friendly gardening

Five helpful tips to help you keep invasive plant species out of your garden…and out of wetlands

Purple loosestrife is an aggressive invasive plant that can spread to local wetlands, reducing their biodiversity. ©Jade Raizenne
Purple loosestrife is an aggressive invasive plant that can spread to local wetlands, reducing their biodiversity. ©Jade Raizenne

The days are getting longer – and warmer. Waterfowl are settling in to nest. It’s official: spring is here.

Green thumbs across Canada are itching to dig deep into the soil and begin planting. If you’re a conservation-minded gardener, you might be considering a naturalized garden to provide food and shelter for wildlife.

But before you visit a local garden centre to make your plant purchases, do your research, says an expert at Native Plant Solutions (NPS) a business line of Ducks Unlimited Canada specializing in naturalized stormwater pond construction and native prairie installations.

You’ll be doing your local wetlands a favour.

“Most consumers assume that if they can buy it, it must be safe to plant,” says Jade Raizenne, a NPS plant ecologist and avid green thumb.

Just because a plant is for sale doesn’t mean it’s safe for your flower patch. In fact, it may be an invasive species or noxious weed. An invasive species planted in your garden can spread to ditches, fields and eventually your local wetland. It can quickly form thick monocultures, overrun wetlands and out-compete native plants that wildlife depend on to survive.

One common example is the eye-catching, yet destructive, purple loosestrife (Lythrum salicaria). Since its introduction to North America from Europe in the 1800s, the plant has made its way across Canada via waterways. Purple loosestrife is an aggressive invader with a tolerance to growing in a wide range of site conditions – from standing water to dry sites.

It spreads rapidly by seed, and by pieces of stems or roots, making it extremely hard to get rid of once it takes a foothold. “It’s likely that the majority of wild infestations of purple loosestrife are the result of garden escapes,” explains Raizenne.

So how can a conservation-minded gardener plant a wetland-friendly garden? Raizenne offers the following tips:

Start online, then take it offline

The Internet can be an invaluable resource for gardening information relevant to your geographic area. So before you lift your trowel, click and scroll online.

“A good start would be to research local invasive species councils, where information and pictures of invasive plants to avoid are listed,” suggests Raizenne.

Take your investigation offline by connecting with a local expert. “It can be difficult for the public to know which plants are actually native in their area. Find a local garden centre that specializes in selling native plants,” says Raizenne.

Scientific names matter

As you research plants, you might want to brush up on your Latin. This “dead” language is alive and well in binominal nomenclature, the formal system of naming all living species – including plants.

“When buying plants or seeds, make sure the genus and species name of the plant is advertised, and it’s not just the common name,” says Raizenne. This is important because a plant can have many common names but only one scientific name.

If you know a plant’s scientific handle, you can avoid purchasing invasive species that may out-compete native plants for resources. One example of a genus that has native and invasive species in the family tree is Iris.

“Yellow flag iris, yellow iris and water-flag are common names of Iris pseudacorus, an invasive species. However, blue flag iris, northern blue-flag iris and wild iris are common names of Iris versicolor, which is native to Canada,” says Raizenne.

Think twice about “great” deals

“Lower prices and exotic options may attract some gardeners to shop online and in garden catalogues,” says Raizenne.

If the deal seems too good to be true, proceed with caution.

“Some seeds are sold online and in garden catalogues as a wildflower or a wildlife habitat seed mix. These seed mixes will often include both native species and non-native species, some of which are invasive,” says Raizenne.

Invasive species that are often included in these mixes include oxe-eye (Shasta) daisy (Leucanthemum vulgare), bird vetch (Vicia cracca), baby’s breath (Gypsophila paniculata), dame’s rocket (Hesperis matronalis), common tansy (Tanacetum vulgare), and many others.

“Consult with your local garden centre to verify the seed you purchase is native and grown from seed collected locally,” says Raizenne.

Get the look without the fallout

Growing a wetland-friendly garden doesn’t mean you have to make sacrifices to get the look you want.

“If you like the look of a plant like purple loosestrife, a good alternative could be meadow blazing star (Liatris ligulistylis), or spiked blazing star (Liatris spicata),” says Raizenne. Unlike purple loosestrife, meadow and spiked blazing star are native to Canada and attract monarch butterflies, bumblebees and hummingbirds to your yard.

Have fun!

The final step is to have fun with your gardening. Once you’ve done the research, it’s time to get outside and get planting.

By following these tips you’ll support your local ecosystem with a sustainable garden that is adapted to local conditions. Bonus: you’ll protect wetlands from invasive plants at the same time.

Growing local: Native plant species to include in your wetland-friendly garden

Common name: softstem bulrush, great bulrush Scientific name: Schoenoplectus tabernaemontani Why we love it: This beautiful wetland plant would make a good addition around pond margins and in water gardens. ©NPS
Common name: blue flag iris, northern blueflag, wild iris Scientific name: Iris versicolor Why we love it: As Quebec’s provincial flower, it should come as little surprise that this striking native plant is most commonly found in wetlands and gardens in Eastern Canada.
Common names: meadow blazing star, spiked blazing star Scientific names: Liatris ligulistylis, Liatris spicata Why we love them: Commonly referred to as butterfly magnets, these plants are also popular with bumblebees and occasionally attract hummingbirds and goldfinches. ©Gord MacKay
Common names: swamp milkweed, Joe Pye Scientific names: Asclepias incarnata, Eutrochium purpureum Why we love them: Showy pink flower clusters on both of these plants would beautify a moist to wet garden. Swamp milkweed is a host species for caterpillars of the monarch butterfly. Joe Pye is an excellent nectar plant for butterflies. ©NPS


Julielee Stitt

Julielee Stitt

Julielee Stitt is a communications coordinator for Ducks Unlimited Canada.

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