Creeping groundcovers can be invaluable allies in the garden: plant a few and they multiply and spread, filling the empty spaces in our flowerbeds without our having to intervene. Especially those that tolerate shade, as they sometimes grow even under other plants, acting as a living mulch. What more could a laidback gardener ask for?
Priority Invasive Exotic Plant Species
Those who are less lazy, on the other hand, may appreciate them less, since they tend to get out of hand. Some even go so far as to call these plants invasive. What an insult! For my part, I prefer to save this word for plants that are truly invasive, such as Japanese knotweed, garlic mustard or Norway maple: plants that come to us from abroad by accident or that have escaped cultivation and are causing real problems by disrupting our ecosystems and sometimes our economy. Here in Quebec, they are known as priority invasive exotic plant species (PIEFS).
However, there is a whole list of plants that are not named PIEPS, but which tend to spread, either by their rhizomes, stolons or seeds. Others could become problematic in the future, but in-depth research has yet to be carried out. And, to complicate matters further, exotic plants may be invasive in some areas, but not in others. A real mess for our readers!
Awareness and native planting
You’re probably wondering why I’m worrying you with all this and, more importantly, what to do about it. First of all, I think we need to be aware of the issue of invasive plants. Unfortunately, many nurseries still sell plants considered PIEPS in Quebec. If they are still selling invasive plants, they certainly won’t advise you on species whose status is uncertain. I’m not asking you to pull up your periwinkle carpet or Japanese pachysandra either, but keep an eye on them, especially if you live near woodlands or protected areas.
Fortunately, there’s a simple solution to this problem: plant native groundcovers! Here are 5 species of ground-covering perennials and shrubs you can use in the garden, without worrying about them running away from home. And they’re common enough that you may already have some in your home without knowing they’re native.
Canadian Wild Ginger (Asarum canadense)
Canadian wild ginger used to be found throughout the forests of eastern North America. It is now quite rare, having been harvested for its medicinal virtues. Although it produces small brown inflorescences, its main interest lies in its ability to spread its green leaves quite aggressively in the shade. Only 15 cm high, it will smother lower plants, including weeds, under a dense carpet of greenery, but will take time to establish. It’s also a very hardy perennial, surviving up to zone 1 USDA.
Bearberry (Arctostaphylos uva-ursi)
I’ve often used bearberry for curb appeal because of its salt resistance, but this creeping shrub can adapt to almost any condition, even deep shade. Native to Canada’s Far North and Greenland, it can be found as far away as New England, on the tundra, at the top of mountains, along coastlines and in forests. Its origins give it good resistance to the cold; it can grow in zone 1 or even zone 0!
Its main attraction remains its evergreen foliage, which turns bronze in winter, but it still produces an enormous number of small white flowers in spring, and fruits that delight birds (and bears, perhaps?). Rarely exceeding 40 cm in height, bearberry can still require a little vigilance, as it has a tendency to spread.
Virginia bluebells (Mertensia virginica)
Virginia bluebells are renowned for their brief but abundant spring flowering, as they live in large groups producing blue flowers on 60 cm stems. Pollinators love it, from native bees to butterflies and hummingbirds. Yet it’s a hardy perennial that adapts equally well to mountain tops and stream banks, resisting wind and snow, but above all shade, where it will produce large green carpets. Delicate as it may seem, it is hardy up to zone 1. It is found mainly in the central and eastern United States, but is native to Quebec and Ontario, where it is considered vulnerable.
American Wintergreen (Gaultheria procumbens)
This small shrub is often used in herbal teas or in the cosmetics industry for its balsamic scent. Yet it’s a champion of northern gardens, with exceptional hardiness, up to zone 1 USDA! Its small, shiny leaves are evergreen, and its creeping branches take root on contact with the ground. In spring, wintergreen produces small white bell-shaped flowers that bear fruit. In August, its red fruits are as impressive as its blossoms. It can be found in the wild from Newfoundland to Manitoba, and as far south as Alabama.
Heartleaf Foamflower (Tiarella cordifolia)
This tiarella, native to eastern North America, is already popular in our gardens and is readily available from nurseries. It’s an understory perennial, so shade-resistant, and spreads by runners. However, it is not invasive. Its heart-shaped flowers are downy and it produces feathery white flowers in spring. Hardy in zone 2 USDA, it will adapt to most gardens.