What are invasive plants?

Everyone loves beautiful plants. Flowers and shrubs adorn our gardens, homes, parks and public spaces. Canadians spend countless hours improving the sensory landscape around their homes, institutions and schools. And many plants attract birds, butterflies and other wildlife seeking food and shelter.

Gardeners have a long tradition of moving plants to new regions, and the popularity of gardening has increased the importation of plants into Canada from other regions of the world. British Columbia’s range of climates – from the maritime climate on southeastern Vancouver Island, to the varied continental regimes through the Interior – allow gardeners to grow a wide range of interesting trees, shrubs and flowers.

Invasive plants are alien species that have the potential to pose undesirable or detrimental impacts on humans, animals or ecosystems. Invasive plants grow rapidly, spread quickly, are tolerant of tough conditions and can form dense patches.

Four Questions to Ask About a New Plant
Before you plant new species in your garden ask yourself these questions:

1. Will the plant be invasive outside my garden?
Many plant traits that are desirable to gardeners, such as easy germination and establishment, tolerance to drought and frost, rapid growth and abundant seed production, enable a plant species to become invasive.

2. If I order a plant from outside British Columbia, could it be invasive in my environment?
It is possible, although there may be a lag phase before a plant becomes invasive.

3. What do I need to know from my local nursery or garden centre?
(a) Find out if a plant is a “fast spreader” or a “vigorous self-seeder.” These are warning signs that the species may be invasive.
(b) Investigate if the plant is known to be invasive elsewhere around the world.

4. Is there an alternate plant I can use instead of one with the potential to become invasive?
Check with garden centres for the availability of non-invasive plants suitable for your area.

Gardeners and Invasives
Invasive plants are capturing the interest and concern of many gardeners. People want to avoid planting ornamental and food species that can spread out of control to other gardens and surrounding grasslands, forests and parks. They also want to eliminate invasive species and noxious weeds from their garden.

Some of the most harmful invasive plants in British Columbia are: purple loosestrife; English ivy; Dalmatian toadflax; Scotch broom; oxeye daisy; giant hogweed; Japanese knotweed and Himalayan blackberry.

Five Things You Can Do About Invasive Plants
1. If you identify an invasive species, remove all of the plant parts and dispose of them carefully.
2. Avoid letting invasive plants fruit or set seed, as birds and animals can spread the plants to other areas.
3. Properly dispose of yard and garden waste and hanging baskets into a properly functioning compost pile or facility.
4. Avoid using wildflower seed mixes, as many consist of invasive species or species not adapted to local conditions.
5. Discourage propagation of invasive species by friends and neighbours. Talk with them about the impacts of invasive plants and the use of suitable alternatives.

Click here for more information about invasive plants.

Information courtesy of the Invasive Plant Council of British Columbia (www.invasiveplantcouncilbc.ca)