Dealing with aggressive weeds and plants is one of the more frustrating and time-consuming tasks for homeowners. As an organic gardener, most of my weeding is done by hand, but there are times I turn to simple techniques like solarizing or smothering to eliminate persistent weeds like goutweed or chickweed.
Many invasives that we see in the home landscape are weeds, undesirable native or introduced plants that spread in lawns and gardens. Common weeds include Japanese knotweed, garlic mustard, bindweed, chickweed and ground ivy. Personally, I don’t consider plants like dandelions and clover to be weeds and tolerate them in my lawn (they even feed the bees!), but when ground ivy begins to choke out my grass it’s time to take action.
It’s not just weeds that can take over a garden bed. Many popular perennials, ground covers, and vines also have invasive growth habits. Plants like goutweed, mint, English ivy, ribbon grass, ajuga, and lily of the valley are all plants with a reputation for outgrowing their boundaries. Goutweed, in particular, quickly creates a large colony, choking out existing or native plants and once established is difficult to control or eradicate.
When looking for ornamental plants for your garden, take a few minutes to do some research before you head to the garden centre. Read labels thoroughly—avoiding plants described as ‘spreading’, ‘vigorous’, or ‘ground-covering’. These are buzzwords for ‘potential problem’!
Most aggressive plants, whether weeds or garden plants, spread in one of three ways: 1) by self-seeding 2) by rhizomes—horizontally growing underground stems 3) by stolons—horizontal stems that grow above on the soil surface.
Dealing with invasive plants
The best way to avoid potential problems is to not add these plants to your lawn and gardens. Of course, that’s often easier said than done, as many people inherit an invasive plant problem with the purchase of their home or others are gifted spreading plants from well-intentioned friends and relatives.
My own battle with goutweed began with a pot of daylilies from the garden of a friend. Little did I know that the pot also contained fragments of goutweed roots that would soon spread across my perennial garden and into my lawn.
In my back lawn, I’ve discouraged weeds by over-seeding the grass with white dutch clover. This low-growing perennial clover is winter hardy in much of Canada and the United States and can be mowed, is tough enough to withstand foot traffic, and supports pollinators with its pretty blooms.
3 ways to deal with invasive lawn and garden plants:
Digging - Mechanically removing weeds from a garden bed or lawn by digging or using a weeding tool is one of the most effective ways to reduce weeds. Aim to remove the entire plant, including all parts of the root system. Digging or pulling weeds just after a rain when the earth is moist can help the roots slip easier from the soil. For very aggressive plants like goutweed whose roots can shatter into many small pieces, expect that it will take multiple diggings to remove the majority of the plants. Keeping on top of invasive weeds does pay off, so be persistent.
Mulching or smothering - Covering the plants of invasive weeds like Japanese knotweed or goutweed is a technique that doesn’t require back-breaking digging, but does take time. Begin by cutting the plants back to ground level with a trimmer fitted with a brush cutting attachment. Next, cover the bed with a thick layer of cardboard, plastic, or a black tarp to prevent light from reaching the plants. Expect to leave the mulch in place for at least a year. If it’s very unsightly, top with bark mulch to disguise the cover.
Solarizing - Solarizing is a great way to prepare a weedy area for a new vegetable, herb, or flower garden by ‘cooking’ existing weed seeds in the soil to prevent future growth. You do need to prep the site first. Begin by cutting down the existing vegetation with a trimmer fitted with a brush cutting attachment, then mow the site to further reduce the height of the remaining weeds. Follow that by rototilling the soil to loosen weed roots, removing these with a hard raking or by hand. Once the site has been cleared, water the soil well and cover with a clear plastic sheet. Solarizing takes around two months and is best done in early to mid-summer when temperatures are high.
Dealing with aggressive weeds as soon as you spot them is one of the best ways to ensure a healthy lawn and garden.
When buying plants, read labels carefully and ask questions of the staff to ensure you don’t bring home a plant that will become aggressive in your garden.
I over-seeded my lawn with white Dutch clover to reduce maintenance, help outcompete weeds, and provide food for pollinators.
