Geographically, it stretches from the Rocky Mountains in the west to the prairies and boreal forests in the east, making it one of Canada’s most diverse regions in terms of landscape.

In terms of climate, this province experiences a continental climate, characterized by warm to hot summers and cold winters. These climatic factors encourage the growth of a wide range of garden weeds.

Additionally, as the sunniest province in Canada with fluctuating moisture levels, Alberta is an ideal environment for persistent and invasive weed species.

This article covers 20 common weeds you’ll find in your outdoor space along with their distinct physical attributes for easy identification. We’ll also recommend the best removal methods to help maintain a healthy, weed‑free garden. 

1. White Clover (Trifolium repens)

• Local Name: White Clover
• Family: Fabaceae
• Annual or Perennial: Perennial

White clover is a perennial creeping plant that generally grows 10-15 cm tall. You can identify it by its three-parted leaflets and white clustered flowers that fade to pink with age. 

It is native to Europe and Asia, and since it was introduced in Canada, it can be found throughout Alberta in a variety of habitats, including residential gardens and lawns.

T. repens aggressively roots at stem nodes, forming large patches in areas around the garden where other plants will not grow.

There are several ways to eliminate white clover. You can manually remove the young plants, grow a vigorous lawn that outcompetes the weed through increased nitrogen fertilization, or increase mowing height, preferably over 3 inches.  

2. Black Medic (Medicago lupulina)

• Local Name: Hop Clover, Black Clover, or Yellow Trefoil
• Family: Fabaceae
• Annual or Perennial: Annual or Short-lived Perennial

Black Medic is a common broadleaf weed in the legume family. It is native to Europe and temperate Asia, but now can be found in many regions across Alberta. You can identify it by its trifoliate leaves and small yellow flowers. 

Like White Clover, Black Medic is a strong indicator of low nitrogen levels in your outdoor landscape. It is a prolific seed producer and grows a deep tap root, quickly becoming invasive. 

Hand-pulling is a viable option for small infestations. Correct compaction, aerate, seed, or fertilize your soil to prevent Black Medic growth.

3. Dandelion (Taraxacum officinale)

• Local Name: Dandelion
• Family: Asteraceae
• Annual or Perennial: Perennial 

Few weeds can scream spring in Alberta like dandelions. Their vigorous growth and bright yellow heads usher in warmer weather after long, cold winters. However, they can also take over gardens, and like other prolific seed-producing weeds, they stick out like a sore thumb. 

You can pull them out by hand and make sure to remove the entire taproot to prevent regrowth. Cutting the weeds before they seed using handy tools can also efficiently remove the weeds. 

4. Quackgrass (Elymus repens)

• Local Name: Quackgrass or Couch Grass
• Family: Poaceae
• Annual or Perennial: Perennial 

Quackgrass is one of the most troublesome weeds in Alberta. The perennial grass can be identified by its linear, light-green leaves and wheat-like spikelets. 

As an aggressive weed, it spreads by seeds and rhizomes and establishes deep roots, taking over gardens quickly. It not only competes with other desirable plants but also diminishes the aesthetic appeal of the outdoor spaces. 

Remove the clumps of grass by hand or through repeated cultivation. Ensure that you remove the rhizome fragments and dispose of them to prevent regrowth. 

5. Purslane (Portulaca oleracea)

• Local Name: Purslane
• Family: Portulacaceae 
• Annual or Perennial: Annual 

Purslane is a native of Northern Africa and Southern Europe, but has been widely naturalized in Alberta. It is a low-growing succulent weed with reddish stems and flat, rubbery leaves that form dense mats in gardens. 

While P. oleracea is adapted to growing in poor soils, you’ll mostly find it in poorly maintained gardens or newly established turf. 

Hand-pulling is generally sufficient to remove purslane weeds, as solitary plants tend to cover large areas. Ensure that all leaves and stems are disposed of correctly. 

6. Canada Thistle (Cirsium arvense)

• Local Name: Canadian Thistle
• Family: Asteraceae
• Annual or Perennial: Perennial

Canada thistle is an aggressive colony-forming weed that grows up to 1.5 m tall. It is easily identified by its lance-shaped, dark green leaves with spiny margins and clusters of pink to purple flowers. 

This noxious weed spreads by seed and creeping roots, quickly overtaking desirable plants and turf in gardens. 

Pull or dig deeply to remove roots or mow before seed set to starve the weed of nutrients.

7. Leafy Spurge (Euphorbia esula)

• Local Name: Leafy Spurge
• Family: Euphorbiaceae
• Annual or Perennial: Perennial 

A native of Europe and Asia, Leafy Spurge was introduced as an ornamental in Alberta and has since been classified as a noxious weed. 

It has clumpy stems, waxy, bluish-green leaves, and small yellowish-green flowers supported by bracts. It forms deep roots (up to 9m) and spreads 4-5m laterally. 

For these reasons, eradicating leafy spurge requires patience (as complete eradication may take time) and a multifaceted approach. Consider hand pulling or mowing for small, young plants and continuous, intensive cultivation for larger plants until complete eradication is achieved.

8. Common Mallow (Malva neglecta)

• Local Name: Garden Mallow
• Family: Malvaceae
• Annual or Perennial: Perennial 

Common Mallow is a herbaceous perennial, erect or prostrate, about 90 cm tall. It has branched and hairy stems, long-stalked, green to purple leaves, and five-petaled white to pinkish flowers. 

While it may provide beautiful blooms for the garden, it can also spread if left unchecked. Digging out the seedlings before they develop woody taproots is the best option. This is achievable before the plant develops four leaves.

9. Creeping Bellflower (Campanula rapunculoides)

• Local Name: Creeping Bellflower
• Family: Campanulaceae
• Annual or Perennial: Perennial 

A common summer garden weed in Alberta, Creeping Bellflower can steal the heart with its bright, bell-shaped, purple flowers. However, it’s an aggressive and invasive plant that tends to take over the entire garden, making it a weed to watch. 

To effectively remove it, use your hands or a small garden shovel and ensure you dig out the entire root system to avoid regrowth.

10. Common Chickweed (Stellaria media)

• Local Name: Chickweed, Nodding Chickweed
• Family: Caryophyllaceae
• Annual or Perennial: Annual or Short-lived Perennial

While it may be native to Europe, Asia, and Northern Africa, chickweed has since been introduced in Canada and can now be found throughout Alberta.

You can identify the winter weed by its egg-shaped to elliptic leaves, small, white, star-shaped flowers, and delicate, prostrate stems that form mats on the ground. 

Remove the weed by hand-pulling or using a digging tool when the ground is moist, as it has shallow roots, and ensure all seeds and stems are well disposed of to prevent regrowth. Mulching the affected area may also control the weed growth.

11. Yellow Nutsedge (Cyperus esculentus)

• Local Name: Yellow Nutgrass, Chufa Sedge, Tigernut, Grass Nutsedge, or Earth Almond
• Family: Cyperaceae
• Annual or Perennial: Perennial 

Yellow Nutsedge is a native weed that you’ll probably find in poorly drained areas in your vegetable or flower garden. The grass-like sedge has yellow-greenish leaf blades and yellow or purple flower heads. 

To get rid of the sedge, repeatedly remove the small plants before they develop tubers. Eliminate the wet conditions in your garden by applying a fabric mulch.

12. Tall Buttercup (Ranunculus acris)

• Local Name: Meadow Buttercup, Field Buttercup, or Giant Buttercup
• Family: Ranunculaceae
• Annual or Perennial: Perennial

Tall Buttercup is a perennial plant that grows up to 1 meter tall. The weed has branched stems, deeply lobed leaves, and bright yellow flowers. 

It is typically found in meadows and pastures but can also grow in gardens, displacing desirable plants through its efficient seed and rhizome propagation. 

Hand-pulling and digging are viable control strategies for small infestations. Mowing and eliminating wet conditions around the garden can also reduce infestations.

13. Annual Bluegrass (Poa annua)

• Local Name: Annual Bluegrass
• Family: Poaceae
• Annual or Perennial: Annual

As the name implies, Bluegrass is an annual grass that is a common and persistent weed in gardens. It is a short-growing grass that competes for resources and also forms dense clumps, overtaking other garden plants. 

Pull or dig out the small grass infestations before seed production. Repeat as many times as possible to achieve complete eradication. 

14. Common Tansy (Tanacetum vulgare)

• Local Name: Garden Tansy or Golden Buttons
• Family: Asteraceae
• Annual or Perennial: Perennial 

Garden Tansy is an Eurasian native that grows 30-150 cm tall. It is easily identified by its clustered stems, alternate fern-like leaves, and golden-yellow button flowers. 

The aromatic perennial spreads by seeds and short underground rhizomes, competing for resources and forming dense patches that can reduce aesthetic appeal. 

The best removal methods are hand-pulling and mowing before seed set.

15. Purple Loosestrife (Lythrum salicaria)

• Local Name: Purple Loosestrife
• Family: Lythraceae
• Annual or Perennial: Perennial 

Purple Loosestrife was once a beloved garden staple for its stunning pink to purple flowers. However, due to its highly invasive nature, it has since been classified as a noxious weed in Alberta and other provinces in Canada. 

It forms numerous brushlike stands that compete for resources and can outcompete other vegetation. Look out for wet areas around your garden because once it establishes, it can cause waterlogging by blocking drainage.

Repeated cutting and mowing of the young plants before they set seed will provide effective control. 

16. Yellow Toadflax (Linaria vulgaris)

• Local Name: Common Toadflax
• Family: Plantaginaceae
• Annual or Perennial: Perennial 

Like many other Eurasian natives, Yellow Toadflax was introduced in Canadian provinces like Alberta as an ornamental and for other economic uses. 

While it can provide stunning lance-shaped leaves and showy yellow blooms to brighten your garden, it can easily escape and aggressively take over. 

Remove by pulling where applicable or incorporate heavy cultivation to ensure you dig out all the root stalks.  

17. Buckhorn Plantain (Plantago lanceolata)

• Local Name: Narrow-leaved Plantain, English Plantain, or Rib Grass
• Family: Plantaginaceae
• Annual or Perennial: Perennial 

Buckhorn Plantain is a common garden weed that grows 30- 60 cm tall. It can be identified by its mature, elongated leaves with whitish midveins that form a basal rosette and a dense cluster of inconspicuous flowers on a cylindrical, upright flowerhead. 

This weed forms dense patches, quickly overtaking other desirable vegetation. It may also be a strong indicator of areas with low fertility. 

Quick removal intervention is vital for this plantain weed. Repeated hand-pulling and digging of the young plants to remove the root system is the best way to eradicate it. Monitor consistently and repeat the control measures as required to prevent regrowth. 

Laying a landscape fabric and organic mulch on seedlings can also limit weed growth and spread. 

18. Lamb’s Quarter (Chenopodium berlandieri) 

• Local Name: Lamb’s Quarter or Pigweed
• Family: Amaranthaceae
• Annual or Perennial: Annual 

Lamb’s Quarter is an annual weed native to Europe and Asia that grows 1-2m tall. It has since spread to many parts of North America, including Alberta, CA. 

The common garden weed tends to produce many seeds, compete for important resources, and grow faster than other vegetation. Its dense growth can also shade out other low-growing plants, leading to their death.

Remove young plants by hand-pulling or apply organic mulch to suppress their growth.

19. Sow Thistle (Sonchus arvensis)

• Local Name: Mash Thistle, Field Thistle, Field Milk Thistle, or Creeping Sow Thistle
• Family: Asteraceae
• Annual or Perennial: Perennial

The perennial sow thistle is a common noxious garden weed throughout Alberta. It has long, slightly toothed leaves, yellow ray flowers, and can grow up to 1.5m tall. 

The weed spreads by seeds, which sprout in mid to late May in Alberta. What makes it a noxious weed is that it grows deep underground roots, such that even small infestations can choke out other desirable plants. 

Remove the young plants before they seed through digging and dispose of the fragments properly. 

20. Kochia (Bassia scoparia)

• Local Name: Tumbleweed
• Family: Amaranthaceae
• Annual or Perennial: Annual 

Kochia is an Eurasian native that was introduced as an ornamental in Canada but has since become a problematic weed, especially in the arid and semi-arid regions of Alberta.

The thick bushy olive green weed grows about 4-5 feet tall. It is a prolific seed producer, resilient in dry and saline conditions, and germinates early, and grows rapidly, encouraging quick spread in gardens.

The good news is that the young plant’s shallow taproots are easy to remove through pulling or hoeing. 

Sylvia Kiragu

Lead Editor for Insight Weeds.

insightweeds.com/

The post 20 Common Weeds in Alberta, CA, You’re Likely to Find in Your Garden appeared first on InsightWeeds.

These varying conditions encourage the growth of a variety of weeds, including persistent annuals and perennial grasses, that can be found in gardens, lawns, open areas, and disturbed sites. 

This post covers 20 common weeds you’ll come across in Ontario’s subregions, including their scientific names and accompanying pictures to aid in identification. We’ll also explain the best removal methods to ensure they don’t take over your outdoor spaces.

1. Lamb’s Quarter (Chenopodium berlandieri) 

• Local Name: White Goosefoot or Common Lambsquarter
• Family: Amaranthaceae
• Annual or Perennial: Annual

Lamb’s Quarter is a summer annual that grows up to 1.8 m. It is native to Europe and Asia, but it is widely spread in many parts of Ontario. The summer annual thrives in gardens and near streams and rivers. It is also a common weed in crop lands, including soybeans and sugar beets.

You can remove the weeds through hand weeding, mowing, tillage (dark tillage), or crop rotation, depending on the area of infestation.

2. White Clover (Trifolium repens)

• Local Name: White Clover
• Family: Fabaceae
• Annual or Perennial: Perennial 

White Clover is a perennial plant that lives about 2-3 years. It is native to Europe and Asia and can be identified by its trifoliate leaves and whitish florets. While it is widely grown as a forage crop in Ontario, it can also become a persistent weed in gardens and lawns. 

Hand weeding is a viable removal option in garden beds where infestations are small. When white clover grows on a lawn, it may require more strategic interventions, like increasing nitrogen fertilization to attain healthy and vigorous grass that can outcompete white clover.

3. Canada Thistle (Cirsium arvense)

• Local Name: Creeping Thistle, Cursed Thistle, Field Thistle, or California Thistle
• Family: Asteraceae
• Annual or Perennial: Perennial

Canada Thistle is a perennial weed that grows up to 1.5 m tall. You can easily identify it by its glossy green leaves with spiny edges, smooth, spineless stem, and small clusters of pink to purple flowers on the ends of the branched stems.

It is one of the most aggressive weeds in Ontario, and its rapid spread can make eradication efforts difficult. Canada thistle invades grasslands, roadsides, crop fields, and lawns. Repeated mowing or cutting them off at ground level before they seed can help limit the spread of the weed. 

4. Large Crabgrass (Digitaria sanguinalis)

• Local Name: Crabgrass, Hairy Crabgrass, or Crab Finger Grass
• Family: Poaceae
• Annual or Perennial: Annual

Large Crabgrass is a common weed in Ontario’s lawns and cultivated fields. While it is a late bloomer, it can weaken even the most manicured turf and overtake large areas through its efficient regeneration. It has also been reported to cause significant and cause yield losses in soybean and corn fields.

Grow a vigorous and well-watered lawn to discourage crabgrass growth. You can also pull out the patches of grass to get rid of the entire rhizome system. 

5. Japanese Knotweed (Fallopia japonica)

• Local Name: Japanese Knotweed
• Family: Polygonaceae
• Annual or Perennial: Perennial 

Japanese Knotweed is a perennial weed easily identified by its broad leaves and creamy white flowers. It is mostly found in the southern and central areas of the province along roadsides, in farmlands, and gardens. 

Grazing, mowing, and other natural methods can help eradicate Japanese Knotweed.

6. Creeping Charlie (Glechoma hederacea)

• Local Name: Creeping Charlie
• Family: Lamicaeae
• Annual or Perennial: Perennial 

Creeping Charlie is a perennial weed, native to Europe and Asia, but now found throughout Ontario. The weed has dark green leaves with serrated edges and small bluish flowers. Its high seed production and ability to propagate vegetatively make it a persistent weed in many subregions. 

To remove Creeping Charlie, try hand-pulling for small infestations and herbicides like Fiesta for larger areas.

7. Field Bindweed (Convolvulvus arvensis)

• Local Name: Field Bindweed
• Family: Convolvulceae
• Annual or Perennial: Perennial 

Field Bindweed is an Eurasian native that can be a creeping or climbing plant about 0.5-2 m long. It can be found throughout Ontario but is commonly associated with the southwestern region in open fields, crop farms, and waste areas. 

You can pull out small patches of the weed by hand or apply natural methods like solarization and boiling water.

8. Common Purslane (Portulaca oleracea)

• Local Name: Purslane or Little Hogweed
• Family: Portulacaceae 
• Annual or Perennial: Annual 

Purslane is a common weed noted for its reddish stems, entire leaves, and dense mats. It is a native of Southern Europe and Northern Africa. 

The short succulent is a prolific seed producer and quick-spreading, making it a notorious weed of lawns, vegetable gardens, open fields, and cultivated lands.

Mulching and solarization can effectively kill the purslane and its seeds. 

9. Creeping Speedwell (Veronica filiformis)

• Local Name: Creeping Speedwell or Hairlike Speedwell
• Family: Plantaginaceae
• Annual or Perennial: Perennial 

Creeping Speedwell is a low-growing weed, native to western Asia and eastern Europe. It has rounded or kidney-shaped leaves at the base of the stem and 4-petaled blue flowers. The weed spreads by nodding on the stems and rhizomes, spreading on gardens, lawns, and sidewalk cracks.

Pull out the young plants and ensure to properly dispose of the stem and rhizome fragments to prevent regrowth. Iron-based herbicides can also provide effective control against Creeping Speedwell.

10. Dandelion (Taraxacum officinale)

• Local Name: Dandelion
• Family: Asteraceae
• Annual or Perennial: Perennial 

Dandelion is a common weed across Ontario’s cultivated fields, lawns, roadsides, and other disturbed sites. The Eurasian native is easily identified by its deeply toothed leaves and showy, yellow flowers. 

Pull solitary weeds while young and ensure to remove the taproot. Digging tools can provide better results when removing the plants and their roots as they grow in spring. 

11. Canada Fleabane (Erigeron canadensis)

• Local Name: Fleabane or Horseweed 
• Family: Asteraceae
• Annual or Perennial: Annual

Canada fleabane is an annual herbaceous plant 1.5 m tall. It has slender, long, and hairy leaves and much-branched, small, white flowers. 

Fleabane is a common weed in Ontario, especially in gardens, pastures, and roadsides. It is a noxious weed in crop fields, causing as high as 90% yield losses in soybean plantations. 

Since it has a taproot, you can remove it by pulling or hoeing. Mowing, tillage, or applying iron-based herbicides in spring or fall can also reduce seed production, dispersion, and growth.

12. Bermudagrass (Cynodon dactylon)

• Local Name: Bermudagrass
• Family: Poaceae
• Annual or Perennial: Perennial 

Bermudagrass is a warm-season grass about 30 cm tall. This resilient grass can grow in all types of soils and weather conditions, has a deep root system, and also spreads through rhizomes. The grass invades lawns, fields, roadsides, row crop farms, and other disturbed areas, mostly in the warmer southwestern Ontario.

Repeated digging of the grass and pulling out the root fragments is the most common way to remove the grass. Mulching and solarization can also work for flat areas.

13. Shepherd’s Purse (Capsella bursa-pastoris)

• Local Name: Shepherd’s Heart, Pick Purse, Poverty Weed, or Beggar’s Tick
• Family: Brassicaceae
• Annual or Perennial: Annual 

Shepherd’s Purse is an annual weed that grows 50-70 cm tall, native to Europe and Asia. You can identify it by its hairy, rounded to oval leaves and small white-petaled flowers. 

In Ontario, it is found in gardens, fields, roadsides, waste areas, and can also be found in winter cereals. 

You can remove the weeds by hand-pulling, hoeing, mulching, or crop rotation to make it difficult for the weeds to establish and spread. 

14. Quackgrass (Elymus repens)

• Local Name: Quitch Grass, Couch Grass, Twitch Grass, or Scutch Grass
• Family: Poaceae
• Annual or Perennial: Perennial 

Quackgrass is a perennial weed (30-120 cm tall) that’s native to Europe and temperate Asia. It has flat, linear leaves about 15-40 cm long and pale-greenish wheat-like spikelets. 

Scutch grass is a problematic weed in lawns, grasslands, and agricultural settings where it not only competes for important resources but also causes poor harvesting when it gets entangled in the crops. 

Whether you want to remove quackgrass from your lawn or crop field, strategies like cultivation, crop competition (planting crops at optimal depth) can prove effective. 

15. Common Ragweed (Ambrosia artemisiifolia)

• Local Name: Short Ragweed
• Family: Asteraceae
• Annual or Perennial: Annual 

Common Ragweed is a native of Central and Northern America, including Ontario, particularly in the southern part of the province. The summer annual can grow up to 1.5 m tall. Its leaves have a fernlike appearance and can produce small yellowish brown flowers.

It is a serious weed of riverbanks, grasslands, and agricultural fields, where it causes catastrophic losses by contaminating harvested produce. 

Remove annual ragweed by hand weeding, mechanical cutting, mowing, or planting red clover as a cover crop. Other removal methods include applying essential oils from clove, cinnamon, and red thyme.

16. Broadleaf Plantain (Plantago major)

• Local Name: Plantain, Common Plantain, Dooryard Plantain, or Doorweed
• Family: Plantaginaceae
• Annual or Perennial: Perennial 

Plantain is a broadleaf weed, native to Europe and Asia, but now also commonly found throughout Ontario. As the name implies, it has broad leaves that grow from a basal rosette and produces inconspicuous, small white flowers.

This resilient weed can withstand foot traffic, water-logging, and compaction, hence its prevalence in open fields, pastures, cropping systems, sports fields, lawns, and waste areas.

For smaller areas, remove the young plants before they seed and monitor to ensure there is no regrowth. 

Hand-pulling or placing a 2-4 inch deep organic mulch in ornamental plantings can prevent seedling growth. For larger infestations, apply a herbicide like Fiesta for effective control.

17. Hairy Nightshade (Solanum physalifolium)

• Local Name: Potatoweed or Brown-berried nightshade
• Family: Solanaceae
• Annual or Perennial: Annual 

Hairy nightshade is a South American native annual that can be identified by its almost sticky stems and ovoid to deltoid leaves and small clusters of star-shaped, white-petaled flowers. 

It is a weed of pastures, crop fields, orchards, vineyards, roadsides, and other disturbed sites. Hairy nightshade not only competes for resources but also hosts several pests and diseases, clogs crop field machinery, and can be toxic to humans and livestock. 

Solarization and repeated tillage are effective against the weed, depending on the area and crop affected.

18. Green Foxtail (Setaria viridis)

• Local Name: Millet, Brush Millet, Bottle Brush, or Bottle Grass
• Family: Poaceae
• Annual or Perennial: Annual

A Eurasian native, Green Foxtail is a tall weed that can reach 1- 2 meters or more. It has long, glabrous leaves and an erect or nodding 20 cm long, compact spike-like panicle. 

The weed is one of the first grasses to emerge in spring, typically after the broadleaf weeds. Green foxtail can be found in gardens, cultivated fields, and roadsides throughout Ontario.

Use a trowel to pull out the weeds from the lawn. Improving turf management through proper irrigation and fertilization can also discourage weed growth. 

19. Mouse Ear Chickweed (Cerastium fontanum)

• Local Name: Mouse Ear or Large Mouse Ear Chickweed
• Family: Caryophyllaceae
• Annual or Perennial: Annual 

Mouse Ear Chickweed is an annual weed that nodes on the stems, forming large and dense low-growing patches. You can identify the weed by its small, oval leaves with entire margins, hairy, reddish-brown stems, and white, deeply notched flowers.

This weed can be located in a range of habitats throughout Ontario, including lawns and cultivated fields.

Pull or dig them out before they flower if spreading in a garden, and ensure to remove all the fragments to avoid resprouting. 

20. Garlic Mustard ( (Alliaria petiolata)

• Local Name: Garlic Mustard
• Family: Brassicaceae
• Annual or Perennial: Biennial

Garlic Mustard is a native of Europe and Asia that was introduced in North America as an edible herb. Today, this tall plant has become one of the top forest invaders in Ontario. 

It has been reported to displace native plants like the Trout Lily (Erythronium americanum) and threaten other species like Wood Poppy (Stylophorum diphyllum) and White Wood Aster (Eurybia divaricata).

Apart from the forests, Garlic Mustard can also be found along trails and roadsides. 

Pull the weeds by hand for small or isolated infestations and dispose of them properly. Prescribed burning or a Fiesta application on actively growing foliage can control medium to large infestations. 

Sylvia Kiragu

Lead Editor for Insight Weeds.

insightweeds.com/

The post 20 Common Weeds in Ontario, CA, With Pictures and Scientific Names appeared first on InsightWeeds.

As such, Maine has many common weeds, ranging from garden weeds to invasive plants in crop fields, roadsides, and undisturbed areas.

You must first learn to identify these weeds to deploy the right control measures to fight them. 

Below is a list of common weeds in Maine, their photos, identifying features, and top ways to eradicate them. 

1. Canada Thistle (Cirsium arvense) 

• Local Name: Canadian thistle; Creeping thistle; Cursed thistle 
• Family: Asteraceae 
• Annual or Perennial: Perennial 

Canada thistle (California thistle, corn thistle, field thistle, or prickly thistle) is a rhizomatous herbaceous plant that grows to 0.3-1.5m tall. 

It has slender, grooved stems that are smooth or occasionally covered with soft hairs. 

The leaves are dark green, oblong, alternately arranged, and directly attached to the stems. The basal leaves reach 12-20cm long. 

They also have lobed or toothed margins, short white hairs on the underside, and sharp, prickly spines along the margin. 

The plant produces several attractive purple flowers that bloom at the top of branching stems. The flowers are tubular and covered with green bracts with hints of purple with weak spines. 

It is native to: 

• Europe
• Western Asia
• Northern Africa

NOTE: Despite the name, Canada thistle is not native to Canada. Instead, it is a widely distributed species in the North American region. 

Removal methods 

• Mechanical control: When the soil is moist, you can hand-pull or dig out young plants. Repeated tillage, mowing, and cutting can prevent seeding, reducing and eventually eradicating infestations. 
• Chemical control: The plant can be eradicated with selective herbicides like 2,4-D, MCPA, dicamba, Bentazon, Clopyralid, chlorsulfuron, and dichlobenil. Non-selective herbicides like glyphosate are also very effective for large infestations. 

2. Bird Vetch (Vicia cracca)

• Local Name: Cow vetch; bird vetch; tufted vetch; boreal vetch
• Family: Fabaceae
• Annual or Perennial: Perennial 

Bird vetch is a perennial climbing plant that can grow to 1m (sometimes 2m) tall. 

Its weak, hairy stems have noose-like branched tendrils that fasten around other plants for support and can easily suffocate smaller plants. 

It has gray-green, alternate, and pinnate leaves. Each leaf has 8-12 pairs of small (5-10mm long) ovate leaflets with short hairs, a smooth margin, and a rounded to abruptly pointed tip. 

The plant produces conspicuous, pea-shaped violet flowers, which grow in clusters (one-sided) along a raceme that rises out of the leaf axils in the upper stems. 

It also bears a flattened pea pod containing 2-8 round or oval-shaped seeds. 

Vicia cracca is native to Asia and Europe. However, it is widely distributed worldwide, including in North America. 

Removal methods

• Mechanical control: Hand-pulling and regular mowing when the plants are young can prevent seeding. When performed regularly, these practices can diminish small infestations. 
• Chemical control: Systemic herbicides like glyphosate and clopyralid effectively eradicate bird vetch. Other effective herbicides include 2,4-D and triclopyr. 

3. Spiny Sowthistle (Sonchus asper)   

• Local Name: Spiny sowthistle or Spiny-leaved sowthistle
• Family: Asteraceae
• Annual or Perennial: Annual

Spiny sowthistle (prickly show-thistle, rough milk thistle, or sharp-fringed sow thistle) is an erect, annual (sometimes biennial) plant that can grow 100-150cm tall. 

It has green to reddish, stout stems, which are hairless, hollow inside, and release a milky sap when broken. 

Sonchus asper has glossy, bluish-green leaves that are simple, alternately arranged, lanceolate in shape, and lobed with margins. 

The leaf blades can reach 10 inches long by 3.5 inches wide and are covered with spines at the margins and the undersides. 

The plant produces gold to yellow flowers that emerge from the leaf axis at the tip of the stem. Each flower head contains several yellow ray florets with no central disc. 

It is native to: 

• Europe
• North Africa
• Asia 

Removal methods

• Mechanical control: Small infestations can be pulled out by hand when the plants are young and before seeding. Repeated mowing, tillage, and cutting shoots can prevent seeding and overwhelm spiny sowthistle. 
• Chemical control: The weed can be eradicated using various chemical herbicides, such as 2,4-D, diuron, isoxaben, atrazine, glyphosate, Picloram, oxyfluorfen, paraquat, and others. 

4. Field Bindweed (Convolvulus arvensis) 

• Local Name: Morning glory 
• Family: Convolvulaceae
• Annual or Perennial: Perennial 

Field bindweed (creeping jenny or perennial morning glory) is a rhizomatous climbing or creeping plant that grows to 0.5-2 meters long. 

It has weak, intertwining stems that are usually prostate, creating a thick ground cover. 

Convolvulus arvensis has arrow-shaped, spirally arranged leaves attached to the stems by a short petiole. The leaf blades are 2-5cm long and have a lobed base, pointed tip, and an entire margin. 

It also produces showy, white (or pink) trumpet-shaped flowers that bloom in the summer. 

The flowers have two tiny bracts with a smooth surface (or fine hairs) and resemble those of true morning glory, hence the common name. 

Convolvulus arvensis is native to Europe and parts of Asia. However, it is a widely distributed species in North America. 

Removal methods

• Mechanical control: Small patches of young plants can be pulled out by hand. Repeated cutting can also control the plant and gradually diminish the infestation. 
• Natural control: Natural remedies like solarization, boiling water, and vinegar-soap solution can be effective against small patches of young plants. 
• Chemical control: Glyphosate is the most effective method of eradicating field bindweed. Other effective herbicides include dicamba, 2,4-D, Picloram, paraquat, and quinclorac. 

5. Cypress Spurge (Euphorbia cyparissias)

• Local Name: Cypress spurge; Graveyard moss; Graveyard weed; Bonaparte’s crown
• Family: Euphorbiaceae
• Annual or Perennial: Perennial 

Cypress spurge is a low-growing perennial herb with erect stems reaching 20-40cm in height. It has branching stems and can spread aggressively using a rhizomatous root system, forming a thick, bushy ground cover. 

It has narrow (4cm long by 1-2mm wide), needle-like, blue-green leaves arranged in a spiral pattern around the stem. The leaves have an entire margin and, when broken, release a milky sap toxic to the skin. 

The plant produces showy, bright yellow flowers that bloom in clusters at the stems tips. Each flower has two yellowish-green, round to heart-shaped bracts resembling petals. 

Euphorbia cyparissias is native to Europe. It was introduced to North America as an ornamental plant but is now considered a noxious invasive species in many regions. 

Removal methods

• Mechanical control: Hand-pulling or digging out is effective when dealing with small, new infestations. The soil should be moist for the best results, and protective equipment should be worn to protect against the toxic milky sap. 
• Cultural control: Cultural practices like mulching, proper fertilization, and keeping desired plants healthy can control or prevent Cypress spurge infestation.  
• Chemical control: You can eradicate the weed using chemical herbicides like 2,4-D, dicamba, and quinclorac (applied at the flowering stage) or Picloram (applied at full bloom or during the re-growth stage). 

6. Purple Loosestrife (Lythrum salicaria) 

• Local Name: Purple Loosestrife
• Family: Lythraceaea
• Annual or Perennial: Perennial 

Purple loosestrife (purple Lythrum or spiked loosestrife) is an erect-growing perennial herb that can reach 0.5-2.0m in height. It has four-angled, smooth, or hairy stems and a strongly developed taproot system. 

The plant has simple, opposite, lanceolate, dark-green leaves with an entire margin. The leaf blades are stalkless and grow to 3.8-10.2cm long. 

From mid-late summer, the plant produces attractive, deep pink, purplish flowers that form in clustered spikes at the tip of the stems. Individual flowers have about 5-7 tiny petals and 10-14 stamens. 

It is native to: 

• Europe
• Asia
• North Africa
• Australia 

It was introduced in North America as an ornamental plant and accidentally through contaminated soil used for ship ballast. 

Removal methods

7. Common Yellow Woodsorrel (Oxalis stricta) 

• Local Name: Yellow woodsorrel; common yellow oxalis; lemon clover
• Family: Oxalidaceae
• Annual or Perennial: Perennial (sometimes annual) 

Common yellow woodsorrel is perennial and grows up to 23cm tall. It has several smooth (or slightly hairy) stems that emerge from the base of the plant and can either grow upright or sprawl on the ground. 

It has light-green alternately arranged trifoliate leaves that resemble those of clover. Each leaflet is heart-shaped, about 2cm wide, and folds upward in half during the night or when stressed. 

The plant has bright yellow flowers with five petals that form an open cup shape. From mid-spring to fall, the flowers bloom individually or in small clusters of up to five. 

It also bears capsule fruits that look like tiny okra pods, which are hairy and ribbed. The pods open up explosively when mature, dispersing tiny, brown seeds. 

It is native to: 

• North America 
• Europe 
• Asia

Removal methods

• Mechanical control: Young plants can be hand-pulled or dug up before seeding. This should be done when the soil is moist to ensure complete plant removal, including the root rhizomes. 
• Chemical control: It can be eradicated using post-emergent herbicides like glyphosate, sulfentrazone, isoxaben, flumioxazin, and indaziflam. Pre-emergent herbicides can also prevent the emergence of new plants from the seeds or rhizomes. 

8. Annual Ragweed (Ambrosia artemisiifolia)

• Local Name: Common ragweed; short ragweed
• Family: Asteraceae 
• Annual or Perennial: Annual 

Annual ragweed (common ragweed, bitterweed, hay fever weed, or blackweed) is a summer annual plant that grows up to 6 feet tall. It has erect, branching, hairy, light pink to red stems. 

It has compound, fern-like, toothed, and deeply lobed leaves that measure about 4-10cm long. The leaves, oppositely arranged on the stem, are hairy when young but become smooth as they age. 

From late summer, the plant starts producing inconspicuous green flowers in slender, long spikes that turn yellowish or brown. 

The male flowers release massive amounts of tiny yellow pollen that causes hay fever. 

It is native to: 

• Canada 
• U.S.A
• Alaska
• South America (Brazil, Paraguay, Chile, Peru, Bolivia, Brazil, and Argentina)
• Cuba
• Jamaica
• Hispaniola 

Removal methods 

• Mechanical control: Hand-pulling or digging can be effective for small patches, but it is best done when the plants are young and before seeding. Repeated tillage (before seeding) can also control the spread of the weed. 
• Biological control: Ophraella communa and Zygogramma suturalis, two species of ragweed leaf beetle, have been used to control common ragweed with very positive results. 
• Chemical control: Herbicides like glyphosate, Metsulfuron, and glufosinate can eradicate the crop. However, repeated applications may be necessary when dealing with large infestations. 

9. Hairy Galinsoga (Galinsoga quadriradiata) 

• Local Name: Shaggy soldier 
• Family: Asteraceae 

Hairy galinsoga (shaggy soldier or Peruvian daisy) is an annual herb that grows 10-60cm tall. It has upright, branching stems, which are covered by dense hairs. 

Its leaves ovate, oppositely arranged along the stem and with coarsely toothed margins. The leaves, like stems, are covered with dense hairs, giving them a velvety appearance. 

The plant produces small flower heads that form at the tip of the stem from the leaf axils and can bloom in a clustered pattern. 

Each flower head has a central disc of yellow florets surrounded by 4-5 white ray florets. 

Galinsoga quadriradiata is native to Mexico. However, it is widely distributed in several other places, including: 

• North America
• South America
• Europe
• Asia 

Removal methods  

• Mechanical control: Hand pulling and digging out can be effective for small patches of young plants. However, removed parts of the plant must be disposed of carefully as Galinsoga can re-root from cut stems. 
• Cultural control: Cultural practices like crop rotation, use of cover crops, and mulching can help control the spread (or prevent encroachment) of the weed, but they cannot eradicate it. 
• Chemical control: Galinsogacan can be eradicated using post-emergence herbicides like glyphosate, glufosinate, and diquat. Pre-emergence herbicides like flumioxazin and isoxaben can also control new germinations.  

10. Shepherd’s Purse (Capsella bursa-pastoris)

• Local Name: Shepherd’s purse 
• Family: Brassicaceae
• Annual or Perennial: Annual 

Shepherd’s purse is an aggressive-growing annual plant in the mustard family that reaches 10-50 (and occasionally 70cm) in height. Its slender, green to purplish stems are covered by gray hairs. 

The basal leaves of Shepherd’s purse grow in a rosette pattern (reaching 3-15cm long by 4cm wide), while upper leaves are arranged alternately on the stem. 

The leaf blades are hairy and can be round to oval-shaped, smooth, toothed, or deeply lobed on the edges. 

The plant produces small flowers with four rounded white petals and six yellowish-green stamens at the center. 

The flowers bloom in clusters at the tip of the stems and later develop into flattened, triangular, heart-shaped seed pods containing several tiny seeds.  

Capsella bursa-pastoris is native to Europe and parts of Asia. However, it is widely distributed worldwide, including in North America, South America, Asia, Africa, the Mediterranean, and Australia. 

Removal methods 

• Mechanical control: Hand-pulling and cultivation are effective on young plants before they seed. 
• Cultural control: Mulching, crop rotation, and planting competitive beneficial crops can control the spread of Shepherd’s purse. 
• Chemical control: It can be eradicated using post-emergent herbicides like Bentazon, flumioxazin, glyphosate, diquat, and flumioxazin. Pre-emergent herbicides like oxadiazon, pendimethalin, and oxyfluorfen can control new germinations. 

11. Quackgrass (Elymus repens)    

• Local Name: Couch grass; Quickgrass; Witchgrass
• Family: Poaceae 
• Annual or Perennial: Perennial 

Quackgrass is a perennial grass with rhizomatous roots that can grow to 40-150cm tall. It can be easily identified by the claw-like auricles that clasp around the stem. 

It has alternate, ascending leaves that reach 12 inches long and 10mm wide. The leaf blades are flat, stiff, pointed at the apex, and sometimes covered with hairs on the upper surfaces. 

The grass produces clusters of flowers that form on a single, erect spike at the tip of the stems. 

Each spikelet is about 2-8 inches long and has two rows of greenish-blue flowers that turn into a tan straw color when dry. 

It is native to: 

• Europe
• Asia 
• Northwest Africa
• The Arctic

Removal methods 

• Mechanical control: When the soil is moist, young plants can be pulled from the ground (before seeding). Mature plants can also be dug out (from the rhizomes) using gardening tools, but this is very labor-intensive. 
• Cultural control: Mulching, maintaining healthy lawns or beneficial crops, re-seeding of lawns, proper fertilization, and planting of cover crops can control the spread of Quackgrass.
• Natural control:  You can kill infestations of Quackgrass by covering them with a plastic mulch or repeatedly burning them. 
• Chemical control: It can be eliminated using glyphosate, atrazine, imazapyr, and grass-selective herbicides. 

You can check out our quackgrass elimination guide for more methods in detail.

12. Lambsquarters (Chenopodium album) 

• Local Name: Lambsquarters; White goosefoot  
• Family: Amaranthaceae
• Annual or Perennial: Annual 

Lambsquarters is a fast-growing plant in the Amaranth family that reaches 10-150cm in height. It has upright reddish to purplish stems with streaks of green that can be covered with sparse hairs. 

It has dull green-bluish leaves that are toothed, opposite or alternately arranged, and varying in shape from triangle to diamond or lance-shaped. 

The leaf blades vary in size, reaching 2-14cm long by 1-6cm wide, with the basal leaves larger than the upper ones. 

The plant produces inconspicuous green flowers that bloom in clusters at the top of the stems. The flowers do not have petals and are covered with a powdery coat, just like the leaves. 

Chenopodium album is native to Europe and Asia. It is also widely distributed worldwide, including in North America and countries like Nepal and India, where it is cultivated as a food crop. 

Removal methods

• Mechanical control: You can hand-pull young plants before they start seeding. Repeated light tillage and cutting to the stem can also control the weed and eventually overwhelm the seed bank. 
• Cultural control: You can control (but not eradicate) weeds through cultural practices like mulching, planting cover crops, and maintaining healthy, beneficial crops. 
• Chemical control: Herbicides like 2,4-D, Aminopyralid, Chlorsulfuron, glyphosate, Hexazinone, imazapyr, paraquat, Picloram, and triclopyr are very effective at eradication. 

13. Giant Hogweed (Heracleum mantegazzianum) 

• Local Name: Giant hogweed; Giant cow parsnip 
• Family: Apiaceae
• Annual or Perennial: Perennial 

Giant hogweed is a perennial (sometimes biennial) herbaceous plant that grows 2-5m tall. Its hollow, green stems with purple specks are covered with coarse white hairs. 

Its leaves are alternately arranged, with deep, irregular lobes and sharp, toothed margins. The leaf blades are large and can reach 1-1.5m long when mature. 

The plant produces several tiny, clustered flowers at the stem’s tip, forming a compound umbel. The umbels are large, with each one reaching up to 2.5 feet wide. 

Giant hogweed produces a clear, toxic sap, which reacts with sunlight when exposed to the skin, causing painful blisters. Therefore, despite its attractive flower blooms, it is one of the most noxious weeds in Maine. 

The plant is native to some parts of Europe and Asia but widely distributed worldwide, including North America, New Zealand, and the United Kingdom. 

Removal methods

• Mechanical control: Repeated cutting and mowing can prevent new seed formation and overwhelm the plant, depleting the seed bank and stored root reserves. However, this increases the risk of contact with the toxic sap. 
• Cultural control: Sheep and cattle like grazing on the plant, and repeated intense grazing can overwhelm it, reducing infestation. 
• Chemical control: Herbicides like glyphosate and triclopyr can eradicate giant hogweed. However, repeated treatments are needed to eliminate infestations. 

14. Curly Dock (Rumex crispus) 

• Local Name: Curly dock; Curled dock; Yellow dock; Sour dock; Narrow dock
• Family: Polygonaceae
• Annual or Perennial: Perennial 

Curly dock is a perennial flowering plant that grows to 1.5 meters tall. It has upright, grooved stems with swollen nodes and hairy sheaths that form around the nodes. 

It has large, dull-green basal leaves that can grow to 14-24cm long and are lanceolate with curvy margins. Conversely, the upper leaves are smaller, alternately arranged, and attached to the stem by a long petiole. 

The plant produces clustered flowers at the tip of the stem, which tower over the foliage. The flowers, which lack petals, are greenish but turn reddish-brown when mature. 

Rumex crispus is native to Europe and Asia. However, it is widely distributed in temperate regions of the U.S.A. and Canada. 

Removal methods

• Manual control: Hand-pulling or digging out with gardening tools can effectively deal with young plants. However, the entire plant must be removed from the taproot, or it will regrow. 
• Mechanical control: Repeated tillage, mowing, and cutting down the plant to the roots can prevent new seeding and gradually reduce the infestation. 
• Cultural control: Mulching, improving draining, crop rotation, and planting cover crops can help control the spread of curly dock. 
• Chemical control: Curly dock can be eradicated using various herbicides, such as 2,4-D, Aminopyralid, clopyralid, dicamba, Picloram, triclopyr, glyphosate, chlorsulfuron, Hexazinone, and sulfometuron.  

15. Common Buttercup (Ranunculus acris) 

• Local Name: Common buttercup; Tall buttercup; Tall crowfoot
• Family: Ranunculaceae
• Annual or Perennial: Perennial 

Common buttercup is a perennial herbaceous plant that grows 30-100cm tall. Its green, hairy stems are hollow and heavily branched at the top. 

It has mid-green, hairy leaves divided into 3-5 lobes, each with a toothed margin. The leaves are large, reaching 4 inches long and 6 inches wide. 

The plant bears showy, glossy yellow flowers that form at the tip of the stem, rising from the leaf axils. Each flower has five to seven yellow petals and numerous yellow stamens at the center. 

Although common buttercup is easy to spot in Maine, it is native to: 

• Europe
• Far East Russia
• Greenland
• Aleutian Islands

Removal methods 

• Mechanical control: Hand-pulling and digging can control small patches of Ranunculus acris. Frequent mowing and cutting the stems to the roots can reduce the weed’s vigor and prevent new seeding. 
• Chemical control: It can be eradicated by spraying with herbicides like glyphosate, MCPA, Metsulfuron, dicamba, and aminopyralid. However, several treatments might be required to eradicate the weed, including its seed bank. 

Sylvia Kiragu

Lead Editor for Insight Weeds.

insightweeds.com/

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