Weed Identification Resource Guide

Weeds are plants that are considered undesirable in that particular space. These plants compete with your desired fruit, vegetables, or flowers for nutrients, water, space, and light in your garden.  

There are hundreds of known garden weeds, some of which are invasive species. The following are the top ten weeds found in Ontario backyard gardens, as determined by your Halton Food Expert Gardeners.  

The Top Ten Weeds in Your Garden 

No 1. Dandelion – Dandelions are a perennial plant with jagged, rosette leaves, and bright yellow flowers. Dandelions have very deep roots, making hand-weeding often ineffective (unless done over a length of time). A hand trowel could allow for more effective removal of the entire dandelion, root included. Dandelions are an important food source for pollinators, especially early in the growing season.  

No 2. Plantain – Plantain is a common, perennial plant with large, broad, oval-shaped leaves with curved veins, and long, thin flowers. Plantain leaves often lay close to the ground and are edible. Young plantain leaves can be eaten both raw and cooked. A great way to prepare and consume plantain leaves is blanching the leaves in boiling water before adding them to a salad or freezing for later use. Blanching the leaves makes the previously bitter, fibrous leaves more tender. Plantain leaves also make great additions to teas. 

No 3. Red Root Pigweed – Red root pigweed is an annual plant with red colouration at the roots. Red root pigweed seeds require light for germination, which means that mulching garden beds are an effective way of managing red root pigweed.  

No 4. Lamb’s Quarters – Lamb’s quarters is an edible, fast-growing, annual plant that can be identified by its triangular to diamond-shaped leaves, with its inner leaves covered with a white, powdery coating. Lamb’s quarters should be removed quickly from the garden as it removes moisture from the garden soil quickly. Lamb’s quarters is one of the most common weeds in North America.  

No 5. Purslane – Purslane is an edible, annual plant with small, green paddle-shaped leaves and a red stem. Purslane grows close to the ground and can produce hundreds of thousands of seeds per plant. It thrives in warm weather and moist soil. If purslane is a weed in your garden, the most effective way to manage it is by hand-weeding as often as possible. Mulching garden beds are also an effective way to control purslane weeds. Purslane has a cucumber taste and makes a delicious addition to salads. 

No 6. Bindweed – Bindweed is a tough perennial vine that can be identified by its trumpet-shaped pink and white flowers and arrowhead leaves. Bindweed can incorrectly identified as morning glory (which has a more prominent flower and thicker stem). Bindweed is known to spread quickly and difficult to control. The most effective way to control bindweed is to remove it as early as possible. It is best to remove bindweed about 3 to 4 weeks after germination before it begins to flower. After removal, tarp the affected soil with black garbage bags to heat up past 60°C for several days. This will kill any of the remaining bindweed roots, rootlets, and seeds.  

No 7. Crabgrass – Crabgrass is a summer annual that grows in clumps and is characterized by its broad grass blades. To start, mowing grassy areas regularly will prevent flowering and, thereby, seed production. Crabgrass can be easily controlled in gardens by hand-weeding. Further, crabgrass requires light for germination, making mulching and hoeing useful weed management techniques.  

No 8. Thistle – Thistle is an aggressive perennial weed that can be identified by its spikey adult leaves and purple or yellow flowers. Thistle has extensive root systems, with roots reaching multiple feet in vertical length. When removing thistle, it is important to use gardening gloves due to its spikey leaves and pull the entire root system.  

No 9. Chickweed – Chickweed is a winter annual plant that can be identified by its ten petal, white flower and spade-like leaves. Chickweed grows close to the ground and in dense groupings. Chickweed thrives in moist, cool areas, which means it often appears early in the season. Chickweed can often be found near garden taps or areas where water puddles. Chickweed can be hand-weeded before flowering, and must be eradicated from gardens swiftly as it is a reservoir for pests and viruses.  

No 10. Shepherd’s Purse – Shepherd’s purse is a flowering, annual plant with white, heart-shaped seedpods and toothed, oblong leaves. Shepherd’s purse plants should be removed before flowering. Shepherd’s purse originates from the mustard family, and flowers anywhere from early spring to late fall.  

For images of each of these weeds, check out our Weed Identification downloadable.  

It’s Not All Bad 

It may come as a surprise, but some weeds can be sought after or be beneficial for the space. Weeds can stabilize the soil, add organic matter, and attract pollinators. Some weeds, such as dandelions, lamb’s quarters, and purslane, are edible and nutritious. All in all, weeds are not always bad. 

General Garden Weeding Tips 

First and foremost, it is important to remove weeds quickly and correctly before they start producing seeds. These plants can produce hundreds to thousands of seeds per plant, which will multiply weeds in your garden.  

Weed early and frequently. Check your garden for weeds daily. It is important to remove weeds early as their root system has not established, and it is easier to remove the full weed. Removing weeds young also prevents seeds from spreading. Take breaks while weeding. Do not do weed everything at once, divide your garden into sections or go bed by bed, taking breaks in between.  

Pull the entire weed root out. Take hold of the entire weed and pull the roots out gently. Most importantly, discard the weed properly. Do not leave the weed on the soil surface, instead, dispose in a yard waste bag. Avoid adding weeds to your home compost for use in your vegetable beds. Create a secondary compost with your weeds for use under trees and shrubs. Weeds are easiest to remove fully after a rainfall or watering.  

Top your gardens with mulch. Aside from many other benefits, topping garden beds with mulch will block sunlight from reaching weed seeds. 

Use high quality garden soil and mulch. Ensure you are purchasing high quality, organic, weed-free garden soil and mulch.  

Clean your gardening tools. To prevent the spread of seeds between garden spaces, clean your gardening tools when moving between garden spaces. 

Water the plant directly. Watering the individual plants directly, rather than watering the entire garden space, will prevent the watering of weeds. Conserving water is just the added benefit.    

For more information check out our recent IGTV video on Weed Identification and downloadable Weed Identification resource

Questions? Please email us at .  

Contributed by Alicja Jazwiec, Community Garden Education Assistant 


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