After a cool wet spring, summer has finally arrived and many gardens are starting to showcase their blooms. Cooler conditions this spring in many areas of the province have helped invasive plants to thrive. While spring planting is likely complete, it’s still a good idea to grow plants that benefit the environment in your garden. You probably already know that certain plants are not native to your area; but some of these plants are invasive species which, in addition to not being native, also have the potential to cause economic and environmental harm. This harm comes from the fact that invasive species prey on native species and/or out-compete them for scarce resources.
Invasive plants can also decrease the amount of biodiversity in an area because the predators that would normally prey on plants in their native range do not exist in a non-native environment, allowing the population of non-native plants to grow rapidly.
So which plants are invasive, and how do you get rid of them without harming the environment?
First of all, which plants are invasive species depends on where you live, so make sure you check with a trustworthy resource to determine which plants are not native to your area. The simplest way to do this is to contact your regional invasive plant coordinator. There are a dozen regional groups across BC that are working hard to reduce the impacts of invasive plants and species in your area. To find a regional coordinator near you, access the online map through the ISC website. They are a helpful resource for information, volunteer opportunities, and ways to learn about invasive plants and responsible gardening practices.
Some examples of invasive plants of concern in BC include orange hawkweed (Hieracium aurantiacum), spotted knapweed (Centaurea biebersteinii), sulphur cinquefoil (Potentilla recta), and giant hogweed (Heracleum mantegazzianum). Giant hogweed is becoming more prominent in the Lower Mainland, Fraser Valley, Gulf Islands, and central to southern Vancouver Island due to the cool spring conditions, and is especially bad not only for the environment but because it has a toxic sap that can burn and blister the skin. Once exposed to this toxin, the area of skin affected can be uv-sensitive for several years to come, and if it contacts the eyes, it can cause blindness. This plant is so dangerous that Worksafe BC has a video for safety procedures. Giant hogweed can be confused with native cow parsnip, but giant hogweed has a very large umbrella-like umbel and can grow upwards of 5 meters! It is best NOT to touch or go near this plant if you spot it. For more information about giant hogweed and other invasive plants of provincial concern, click here.
While plants like giant hogweed should be removed carefully based on recommended practices or use of experts for removal, weeding is typically the simplest way of getting rid of invasive species, although it can be rather time-consuming. It is effective for invasive plants such as English ivy (Hedera helix), which resists pesticides and herbicides with its waxy coating. This plant can be gotten rid of by cutting any climbing vines, pulling out the roots with a garden shovel, and putting a deep layer of mulch over the area where it grows. This area should also be monitored in the spring to make sure no new shoots sprout.
There are some invasive plants that grow more aggressively with weeding or mowing, such as orange hawkweed, and that’s way it’s important to learn more about invasive plants impacting your property and the best methods of removal and disposal. It’s almost always best not to compost invasive plants. Instead, bag and incinerate them at the local landfill. It’s even better if you label the bag and put in the appropriate place so these plant fragments don’t also spread to natural areas around the landfill and beyond.
Volunteering with organizations to help stop invasive species in your area is also a good idea. You may make new friends and get some exercise at the same time! Your regional coordinator can link you to events like community weed pulls and other groups active in your area.
It is also a good idea to choose native species for your yard as much as possible. Native species require less maintenance than non-native species because they are by definition ideally adapted to the environment that they are already in. They can also attract local wildlife to your area, which increases the health of your ecosystem. Enjoy summer gardening!