There’s nothing quite like a freshly planted garden or a healthy green lawn—until the weeds show up. Whether it’s dandelions poking through your mulch or creeping charlie taking over your flower beds, garden weeds are a frustrating but fixable part of landscaping in Ontario.

• How to identify common garden weeds in Ontario
• What weeds tell you about your soil and lawn
• How to get rid of weeds in the garden naturally or with products
• The best ways to prevent and reduce weeds long-term

Let’s dig in 🌱

What Are Garden Weeds and Why Do They Matter?

What Counts as a “Weed” in the Garden?

A weed is simply any plant growing where you don’t want it. Some are invasive, some are fast-growing, and others just outcompete your grass or veggies. But all of them have one thing in common: they disrupt your hard work.

What Weeds Tell You About Your Soil

Here’s a fun fact: weeds are often indicators of soil health.

• Dandelions, for example, thrive in compacted soil.
• Clover might mean your lawn has low nitrogen.
• Creeping charlie prefers shady, moist areas.

Identifying the weed can help you improve your landscape from the ground up—literally.

Are All Weeds Bad?

Not always. Some weeds, like milkweed, are important for pollinators. Others, like Queen Anne’s Lace, attract beneficial insects. But left unchecked, even helpful weeds can spread aggressively and smother your favorite plants

Common Garden Weeds Found in Ontario

Here are some of the typical garden weeds you’re likely to find across Southern Ontario:

Dandelions

Everyone knows these bright yellow blooms. Their deep taproots make them hard to pull, and they spread fast through wind-blown seeds.

Tip: Pull after rain or use a weed tool to remove the entire root.

Canada Fleabane

A small, upright plant with white fluffy seeds, this weed is glyphosate-resistant in many areas. It spreads by wind and thrives in low-maintenance lawns.

Creeping Charlie

This vine-like weed loves shade and moist soil. It spreads fast and can choke out groundcovers.

Control method: Pull or use a selective herbicide in spring or fall.

Crabgrass

It appears in hot, sunny areas with bare or compacted soil. Prevent it with thick turf and early spring pre-emergent weed control.

Quackgrass

This tough perennial spreads by underground rhizomes and can be hard to eliminate. It looks like regular grass but grows aggressively.

Broadleaf Plantain

Wide, rubbery leaves that grow in compacted lawns and paths. Tells you the soil might need aeration.

Ragweed and Thistle

Both are allergenic and invasive. Thistles are painful to handle, while ragweed spreads easily and wreaks havoc during allergy season.

👉 For full ID guides and photos, check the Ontario Government’s Weed Identification Guide.

How Weeds Spread and Take Over Your Garden

Weeds are persistent little opportunists. Even when you think you’ve cleared your beds, they find clever ways to sneak back in. Understanding how weeds spread is the first step in stopping them before they take over.

Here are the top ways weeds make themselves at home in your garden:

1. Seeds Carried by Wind, Water, and Wildlife

Many weeds produce tiny seeds equipped with fluff or parachute-like structures that let them drift effortlessly through the air—dandelions and Canada fleabane are classic examples.

Others float on water, or get carried by birds, squirrels, and insects. Even your boots, gloves, and clothing can accidentally bring weed seeds in from other areas of your yard, or from a trip to the park or trail.

2. Underground Roots, Rhizomes, and Runners

Not all weeds rely on seeds—some spread beneath the surface. Perennial weeds like quackgrass, creeping charlie, and Canada thistle send out underground stems or roots called rhizomes and stolons. These can travel several feet away from the main plant, silently establishing new growth wherever there’s space and moisture.

That’s why simply pulling the top of a weed may not be enough—if you leave part of the root behind, it often comes right back stronger.

3. Dormant Seeds Waiting for Sunlight

Weed seeds can lie dormant in your soil for years, just waiting for the right moment—often when you till, dig, or disturb the soil. Once these “sleeping” seeds are exposed to light, air, and warmth, they spring to life.

4. Cross-Contamination from Tools, Mulch, and Compost

Your own tools can turn into delivery vehicles for weeds if you’re not careful. For example:

• A garden tool used in a weedy area and then moved to your clean veggie bed can transport seeds or root fragments.
• Homemade compost that didn’t get hot enough may still contain viable weed seeds.
• Even store-bought mulch or soil, if not high quality, can carry weed seeds

Tip: Always choose trusted, treated options like GardenPro soil from Van Beek’s

How to Get Rid of Garden Weeds (Without Losing Your Mind)

Let’s talk tactics. Here’s how to get rid of weeds in your garden using the most effective and manageable methods.

Hand Pulling and Tools

Sometimes old-school is best. Pull weeds after a rain when the soil is soft. For deep-rooted weeds, a tool like the Gardena weed puller (Canada) makes life easier.

Wear gloves, bring a bucket, and kneel on foam padding for comfort.

Natural Weed Killers

• Vinegar (10–20% acetic acid) works well on young weeds. Spray directly and reapply as needed.
• Boiling water can kill weeds in cracks or small areas
• Smothering with cardboard or newspaper topped with mulch starves weeds of sunlight

Herbicides

For serious infestations, weed killer like Round Up Grass and Weed Killer can help. Use sparingly and only where needed, as it can kill desirable plants too.

Always follow Ontario’s pesticide use regulations and consider spot-treating rather than spraying large areas.

How to Prevent Weeds in the First Place

They say an ounce of prevention is worth a pound of pulling. Here’s how to avoid weeds in your garden from the start:

Use a Garden Weed Barrier

A high-quality garden weed barrier, like landscape fabric, acts like a shield between weed seeds and your soil. It blocks sunlight—so seeds can’t germinate—and keeps your garden looking clean and organized.

• Cut X-shaped holes in the fabric to plant flowers or veggies.
• Lay the fabric tightly to prevent weeds from sneaking through the gaps.
• Cover it with a layer of garden mulch to hold it in place and give your garden a finished look.

This method is especially helpful for new garden beds, raised beds, and perennial areas where you want to limit maintenance.

Apply Garden Mulch

Mulch is one of the most effective and natural weed deterrents out there. A 2–3 inch layer of garden mulch smothers weeds by:

• Blocking light, so seeds can’t sprout
• Retaining moisture, which helps your plants thrive
• Moderating soil temperatures
• Breaking down over time to improve soil health

Choose between organic mulch (like shredded bark, straw, or compost) and inorganic mulch (like stone or rubber, which lasts longer but doesn’t enrich the soil). See our full guide on mulching for more information.

Bonus tip: Keep mulch a few inches away from plant stems to avoid rot and pests.

Maintain a Healthy Lawn

A thick, thriving lawn doesn’t give weeds a chance. Grass competes with weeds for sunlight, water, and nutrients—and if your lawn is strong, it usually wins.

Here’s how to build that lawn fortress:

• Mow High: Keep your mower blade at 3" or higher. Taller grass shades weed seeds and reduces growth.
• Feed Your Soil: Use a premium soil like LawnPro soil to enrich your lawn’s root zone with nutrients and organic matter
• Overseed Bare Spots: Weeds love bare patches. Overseed in spring or early fall to fill them in before weeds move in.
• Water Deeply, Infrequently: Watering deeply (1" per week) encourages deep roots. Shallow, frequent watering only feeds surface weeds.

A lawn care routine like this not only boosts curb appeal—it also builds natural resistance to invasive weeds like clover, dandelions, and crabgrass. For a full breakdown on lawn care see this post.

How to Reduce Weeds in the Garden Long-Term

Weeds are persistent—but so are gardeners. Here’s how to stay ahead:

Maintain a Seasonal Garden Routine

• Spring: Clean up, lay mulch, apply pre-emergent
• Summer: Spot weed and water wisely
• Fall: Remove old plants, lay GardenPro soil, and prep for next season

Aerate Your Lawn

Compacted soil is a weed’s best friend. Aerating helps roots breathe and improves drainage, discouraging weeds like dandelion.

Watch Your Edges

Weeds love to sneak in along fences, sidewalks, and garden beds. Trim borders regularly or fill in edges with low-growing perennials.

Frequently Asked Questions