5 Invasive Shrubs & Grasses We Remove and Replace

When most people think of invasive weeds, they picture fast-spreading groundcovers creeping across the lawn or vines choking out a fence line. But some of the most destructive invaders in our local Ottawa ecosystems are much larger, much taller, and often hiding in plain sight 😨

In fact, many of them were originally planted intentionally. Commonly sold in traditional garden centres as low-maintenance staples for privacy, hedging, or backyard texture, these large invasive shrubs and ornamental grasses quickly escape our yards. Once they make it into local forests and wetlands, they do massive damage, altering soil chemistry, destroying wildlife habitats, and completely pushing out the native species our local ecosystem relies on.

Through our Remove & Replace Service, the REWILD team actively targets these tall invaders to clear the way for healthy, functional, and beautiful native plant spaces.

Here are five of the biggest culprits we remove and replace for our clients:

Japanese Barberry (Berberis thunbergii)

This extremely common landscaping shrub is prized in traditional garden design for its deep purple foliage and thorny branches. Unfortunately, it escapes cultivation easily, spreading into local forest understories where it forms dense, impenetrable thickets that crowd out native wildflowers and tree saplings.

Worse yet, public health and ecological studies have well-documented that the dense, low-to-the-ground foliage of Japanese Barberry creates a highly humid microclimate. This environment is an absolute paradise for blacklegged ticks, significantly increasing tick populations in areas where this shrub is left unchecked.

European & Glossy Buckthorn (Rhamnus cathartica / Frangula alnus)

Buckthorn is one of the most aggressive woody invaders in the Ottawa area. It forms dense, dark stands that completely block essential sunlight from reaching the forest floor, effectively stopping the next generation of native trees from growing.

To make matters worse, buckthorn leaves drop early and decompose rapidly, altering the local soil chemistry to favour its own seedlings while releasing a chemical compound called emodin, which can be toxic to local amphibian populations. We actively clear these out to open the canopy back up and let the soil recover.

Garlic Mustard (Alliaria petiolata)

While it starts small in its first year, by its second year, Garlic Mustard shoots up into a tall, flowering invader that spreads thousands of tiny seeds rapidly via the wind and wildlife.

Garlic Mustard is allelopathic, meaning it releases harmful chemicals directly from its roots into the soil. These chemicals actively disrupt and prevent the growth of native plants and the vital underground fungi (mycorrhizae) that local trees need to absorb nutrients.

Miscanthus Grass (Miscanthus sinensis)

This is a massively popular ornamental grass used to add height and movement to traditional landscapes.

The problem arises in the fall, when its lightweight seeds are easily picked up by the wind and carried into natural meadows, fields, and forest edges. Once established, it creates massive, dense resource-monopolies that crowd out the diverse native meadow species and wildflowers that our local pollinators depend on for survival.

Phragmites (Phragmites australis)

If you have driven past a drainage ditch, roadside, or wetland in Ontario, you have undoubtedly seen Phragmites. This incredibly tall, aggressive reed grows up to 15 feet high, forming dense monocultures that completely take over waterways.

Phragmites completely destroys natural wetland habitats for local turtles, frogs, and birds, and it can even lower local water levels due to how aggressively it consumes resources. Because it spreads so intensely via underground running roots, it requires specialized, careful management to clear away safely.

Let’s Rebuild Your Landscape!

You don't have to let invasive shrubs and grasses control your property or threaten our local biodiversity. Managing these large invaders can feel overwhelming, but replacing them with intentional, ecological native plant communities is one of the most impactful things you can do for the environment right in your own backyard.

If you spot any of these plants spreading through your garden, it is time for an upgrade. Reach out to us today to discuss our Remove and Replace service.