Illinois Weeds – 26 most common

Weeds are pesky plants that can quickly take over a garden or lawn. They are often difficult to get rid of, and can damage crops or trees. There are many different types of weeds, and they can be found in almost every part of the country. Let’s find out about some of the most common Illinois weeds:

garden plants

Table of Contents

Illinios weeds

Name of Weed Family
Bedstraw Rubiaceae
Bindweed Convolvulaceae
Black Medic Legumes
Chickweed Caryophyllaceae
Clover Apiaceae
Crabgrass Poaceae
Creeping Charlie Lamiaceae
Curly Dock Polygonaceae
Dandelions Asteraceae
Field penny-cress Brassicaceae
Horseweed Asteraceae
Knotweed Polygonaceae
Kochia Amaranthaceae
Lambsquarters Violaceae
Nut grass Cyperaceae
Nutsedge Cyperaceae
Pineappleweed Asteraceae
Plantain Plantaginaceae
Purslane Portulacaceae
Ragweed Convolvulaceae
Shepherd's Purse Brassicaceae
Speedwell Plantains
Thistle Daisy
Velvetleaf Abutilonaceae
Wild Violets Violaceae
Yellow Wood Sorrel Oxalidaceae

Bedstraw

Bedstraw is a common weed found in disturbed areas throughout the state of Illinois. It has small white flowers and grows up to three feet tall. This weed is an annual plant, meaning it will die off after one season. Bedstraw prefers full sun and can be difficult to remove from lawns due to its shallow roots.

Type

Annual

Family

Rubiaceae

Control

Several postemergence herbicides are available to help manage bedstraw growth. Oxyfluorfen and glyphosate-based products have proven to be effective. Cultural control measures, such as hand weeding and mulching, can also help reduce the presence of bedstraw in a lawn or garden.

native plants bedstraw

Bindweed

Bindweed, an invasive perennial vine found in the eastern United States, is a fast-growing weed that can quickly overtake any area. Its leaves are arrowhead-shaped and have white patches on their underside. They spread by means of long rhizomes which can grow up to 4 feet in length and form thick mats underground

The flower has five petals and can range from pinkish-white to purple in color. It also produces small round seeds that are easily dispersed through water or wind currents. Bindweed is particularly difficult to control because its roots go deep into the soil and it can regrow from even small pieces of root left behind after removal.

Type

Vine

Family

Convolvulaceae

Control

The only way to get rid of bindweed for good is by using a glyphosate-based weedkiller. This chemical, when applied to the leaves of the plant, will penetrate down into the roots and kill them. However, care must be taken not to spray it onto other plants or areas where it is not wanted.

garden beds Bindweed

Black medic

This small, low-growing annual weed is easily identified by its yellow flowers and clover-like leaves. It has a shallow root system which makes it easy to pull out of the soil, but it can spread quickly if not controlled in time.

Black medic is often considered the first line of defense against larger weeds such as dandelions since its deep roots are able to draw out much-needed moisture from the soil. This makes it an ideal candidate for pre-emergent control because it will prevent other weeds from germinating in areas where black medic has been eliminated.

Type

Broadleaf Annual

Family

Legume

Control

When the soil is moist, hand removal of this weed can be highly effective because it’s much easier to pull out its roots. Therefore, undertaking this task when damp conditions exist will make for a more successful outcome. Alternatively, a herbicide application can also be used to control black medic.

disturbed soil

Chickweed

This weed species is a low-growing, prostrate annual that forms mats of foliage and has small white flowers. It thrives in moist areas with poor drainage, often invading lawns and gardens. Chickweed can be difficult to control due to its ability to spread quickly and germinate from even the smallest amount of soil disturbance.

Chickweed prefers cool weather, so it is most active during the spring and fall. It can be identified by its small white flowers and succulent leaves with a faint sheen or frosty appearance.

Type

Annual

Family

Caryophyllaceae

Control

Chickweed is most rampant in lawns that are kept moist and mowed low to the ground. If you want to prevent its growth, avoid over-watering your lawn in the fall season and raise your mower blade.

If you want to learn more about weeds you can find in Massachusetts then make sure you have read an article I have written that covers this!

low growing grassy weed

Clover

This weed species is an annual with a creeping growth habit and small white flowers. It often invades gardens, lawns, and other areas of the landscape where it can be difficult to control due to its rapid germination capabilities. Clover can be identified by its small, round leaves that have a distinctive clover-like odor when crushed.

It prefers moist soil and grows in full sun or partial shade conditions. The best way to reduce the spread of clover is by preventing it from taking hold in the first place through proper maintenance practices such as mowing regularly and removing dead foliage

Type

Perennial Broadleaf

Family

Apiaceae

Control

Applying a pre-emergent application in the fall is the best way to control clover growth. A healthy, fertilized lawn will also help prevent clover from growing in your lawn. If clover does take hold, post-emergent herbicides can help control it. You may also consider using a mulching mower to grind the weed down and reduce its spread. Additionally, certain nematodes can be applied to lawns to help naturally manage clover infestations.

indigenous weed species

Crabgrass

This weed species is an annual grass that has a low, spreading growth habit and grows in thin blades. It can be difficult to control due to its ability to rapidly spread and germinate from even small amounts of soil disturbance. Crabgrass prefers warm weather and full sun conditions, so it is most active during the summer months. The weed gets its name from the crab-like legs protruding from the stem.

Type

Annual Grass

Family

Poaceae

Control

Crabgrass is opportunistic and will colonize any thin or bare areas in your lawn. Applying a pre-emergent herbicide in the spring is the best way to prevent it from taking hold. If crabgrass does develop, post-emergent herbicides can help control it.

Be sure to mow your lawn regularly to keep the weed in check and allow plenty of sunlight into thin areas so that it is less likely to take hold. Additionally, core aeration helps reduce soil compaction which can also inhibit the growth of crabgrass.

form dense patches

Creeping Charlie

This weed is a perennial broadleaf that spreads quickly and can be difficult to control due to its low-growing habit and vigorous root system. It grows flat along the ground, creating mats of foliage with small, scalloped leaves and pale purple flowers. Creeping Charlie prefers shady areas of the yard but will also grow in full sun conditions when the soil is moist.

Type

Perennial evergreen

Family

Lamiaceae

Control

One of the most effective ways to control Creeping Charlie is by cultivating the soil and removing any existing plants before they have a chance to spread further. A post-emergent herbicide can be used to spot-treat existing weeds, but because of its creeping habit, it is best to apply the herbicide in multiple applications for maximum effect.

turf grasses

Curly Dock

This weed is a perennial with a tall, upright growth habit and large, ruffled leaves that can reach up to 4 feet in height. It has long stems with branched seed heads and yellow-green flowers that turn into brown seedpods by summer. Curly dock thrives in moist soils, poor soil drainage areas, and even lightly shaded areas of the lawn.

Type

Perennial

Family

Polygonaceae

Control

Mowing it down regularly is one of the most effective ways to control curly dock. This will help prevent it from going to seed and spreading further. However, this method should not be used if there are other desirable plants in your lawn, as they can also be damaged by mowing.

perennial plant

Dandelions

This weed species is a perennial with a low-growing growth habit and bright yellow flowers. It is one of the most common lawn weeds, and can be difficult to control due to its aggressive root system and quick germination capabilities

Dandelions are easily identified by their deep taproots, round leaves with jagged edges, and bright yellow flower heads that turn into white puffballs of seeds when mature.

Type

Perennial Broadleaf

Family

Asteraceae

Control

They must be pulled from the taproot up to effectively be exterminated. Pre-emergent herbicides are not effective on dandelions, as they germinate quickly and can easily reestablish from seed. Post-emergent applications will help reduce their spread if applied correctly.

Dandelions

Field penny-cress

This weed species is an annual broadleaf that can quickly spread and germinate from even small amounts of soil disturbance. It has a low-lying growth habit with small, oval leaves and small white flowers that grow in clusters. Field pennycress prefers moist soils, so it is most active during wet spring and summer months.

Type

Summer Annual

Family

Brassicaceae

Control

Hoeing is the most effective way to control field pennycress, as it will help remove weeds before they have a chance to spread and reproduce. Post-emergent herbicides can also be used if the weed is already established but should be applied in multiple applications for maximum effectiveness.

desired plants

Horseweed

Horseweed is an annual weed species that grows rapidly and can reach heights of up to 6-10 feet. It has small, oval-shaped leaves with jagged edges, while its flowers are yellow and resemble daisies. In addition, it produces a large number of tiny seeds which can lead to rapid infestations in lawns and gardens.

Type

Annual Broadleaf

Family

Asteraceae

Control

Utilizing burndown herbicides, like 2,4-D, dicamba, glufosinate (Liberty), saflufenacil (Sharpen) or paraquat (Gramoxone) mixed together can be applied in the springtime or fall season to promote effective management of horseweed.

Horseweed

Knotweed

This weed species is an aggressive perennial with sprawling stems and thick, pointed leaves. It prefers moist soil conditions and can spread quickly, colonizing lawns and gardens alike. Knotweed can be identified by its bright green leaves that are heart-shaped at the base and taper to a point at the tip.

Type

Perennial Broadleaf

Family

Polygonaceae

Control

Knotweed needs to be treated with a systemic herbicide for best results. Digging out the root system is difficult due to its deep-rooted nature, so chemical control is often the only feasible option. Pre-emergent herbicides are not recommended as knotweed germinates quickly from seed.

Knotsweed

Kochia

Kochia is an annual weed species that has a low-growing growth habit and white or greenish-colored flowers. It can be identified by its pointed triangular leaves and long, slender stems. Kochia prefers dry soils and can quickly spread in open areas with little to no vegetation.

Type

Summer Annual

Family

Amaranthaceae

Control

If you want to stop it from germinating, you can use a variety of powerful residual herbicides. For established Kochia, post-emergent herbicides such as glyphosate and 2,4-D can be applied. Spot treatments are recommended to maximize effectiveness and reduce the risk of damage to desirable plants in the lawn.

other garden plants

Lambsquarters

This weed species is an annual with a low to medium growth habit and small, white flowers. It is often found in gardens and lawns where it can quickly spread if not controlled.

Lambsquarters has diamond-shaped leaves that are smooth on the upper surface and whitish beneath, as well as small greenish-white flowers that are grouped together in clusters.

Type

Annual Broadleaf

Family

Amaranthaceae

Control

For effective control of this weed, consider using selective broadleaf herbicides such as 2,4-D or dicamba (Weed Master). If physical removal is preferred, make sure to remove all parts of the plant, including its roots.

Lambsquarters

Nutgrass

Nutgrass is a perennial weed that has light green leaves with a distinct nutty odor when crushed. It can reproduce quickly, forming dense mats that choke out desirable plants in the lawn. Its flowers are small and yellow-white, while its seeds are contained within hard, nut-like shells.

Type

Perennial Grass

Family

Cyperaceae

Control

The best way to control nutgrass is by applying pre- and post-emergent herbicides such as glyphosate (Roundup), acetochlor (Harness Xtra), or mesotrione (Tenacity). For maximum effectiveness, it may require multiple applications throughout the growing season.

Nutgrass

Nutsedge

Nutsedge, also commonly known as Nutgrass, is a perennial weed with bright green leaves and sharp edges. It grows in clumps with yellow flowers that emerge from spikes or “nuts” located at the top of the plant. Nutsedge prefers moist soil and can spread rapidly throughout lawns.

Nutsedge might go unnoticed at first because its seeds look like out-of-season Bermuda grass and thatch.

Type

Perennial Grass

Family

Cyperaceae

Control

Regular maintenance is key when controlling Nutsedge. To achieve a healthy lawn, it is important to have proper mowing and watering schedules. Additionally, post-emergent herbicides can help target established weeds like Nutsedge. Be sure to apply the herbicide during the early stages of growth and follow up with another application as needed.

If you want to learn more about weeds that grow in the State of Georgia then make sure you give an article I wrote earlier which covers this. 

Nutsedge

Pineappleweed

Pineappleweed is an annual weed that has yellow-green leaves and small, pineapple-scented flowers. It can be found in dry, sandy soils or open fields and prefers areas with a high degree of light exposure. Pineappleweed can quickly spread if not monitored or controlled.

Type

Summer Annual

Family

Asteraceae

Control

The best way to control this weed is by using pre-emergent herbicides like trifluralin (Treflan) or pendimethalin (Pendulum). For post-emergent control, products containing glyphosate (Roundup) will do the trick.

Pineappleweed

Plantain

This low-growing weed has wide, green leaves that grow in a circular arrangement. Leafless stalks grow upright from the base, with seeds on the end. Plantain is a tough weed that can survive in almost any condition and prefers heavily trafficked areas.

Type

Perennial Broadleaf

Family

Plantaginaceae

Control

Compacted soil is an ideal condition for Plantain to grow and spread. To control this weed, it is important to core aerate your lawn every year. Additionally, applying post-emergent herbicides targeting broadleaf weeds can help with controlling this stubborn weed.

Plantain

Purslane

Tasty and succulent, purslane (or Portulaca oleracea) is a leafy green vegetable with red stems, small green leaves, and an impressive 93% water content. It can be enjoyed raw or cooked in various dishes under many of its other names such as pigweed, little hogweed, fatweed, and pusley.

It is considered a weed by many but is a healthy, nutritious plant. Purslane contains more omega-3 fatty acids than any other leafy vegetable, plus vitamins B and C, iron, magnesium, calcium and potassium.

Type

Annual Broadleaf

Family

Portulacaceae

Control

Eliminating purslane can be achieved by both manual extraction or chemical control methods. Rainfall and irrigation can help conserve soil moisture, which will reduce its spread. Additionally, broadleaf herbicides such as 2,4-D or dicamba (Weed Master) can also be used to effectively control it.

Purslane

Ragweed

Ragweed is one of the most common and unpleasant weeds in lawns. This tall, annual weed has long stems with small, yellowish-green flowers that produce lots of pollen which is a major cause for hay fever and allergies.

Ragweed grows best in warm, sunny areas such as roadsides, fields, gardens and lawns. It can spread easily from one area to another as its seeds are dispersed by wind or animals.

Type

Annual Broadleaf

Family

Asteraceae

Control

Prevention is the best way to control ragweed. Regular mowing will help keep the plant from growing too tall and going to seed. Hand-pulling can be effective if done when the plant is young but be sure to dispose of the weeds properly as ragweed can easily re-sprout.

Ragweed

Shepherd's Purse

Shepherd’s Purse is an annual weed with white flowers that resemble a flat triangular purse. It can grow up to 10 inches tall and prefers full sun or partial shade. The plant’s roots are shallow, so they can easily spread in garden beds if not removed. The leaves of the shepherd’s purse are often used as a salad green but it should be eaten in moderation as its sap contains irritating acids.

Type

Annual Broadleaf

Family

Brassicaceae

Control

Manually pulling the weeds is the most effective form of control for Shepherd’s Purse since its root system is shallow.

Shepherd's Purse

Speedwell

Have you noticed a purple-hued weed in your lawn? If so, it could very well be Speedwell. This creeping annual grows best among Ohio’s cooler and more humid soils that are also shaded from direct sunlight. With its light blue to purple flowers and brilliant round leaves with scalloped edges, identifying this pest is an easy task for even novice gardeners.

Type

Annual Broadleaf

Family

Plantaginaceae

Control

Speedwells can be successfully controlled by applying specific broadleaf weed herbicides. These herbicides are designed to target and eliminate individual plants, as well as any seeds produced so that the weed does not spread further throughout your lawn. When applying these herbicides it is important to follow the directions on the label carefully and to never apply them.

Speedwell

Thistle

Thistle is a weed that appears to have an attractive purple flower, making it difficult to realize that it’s actually considered a weed. Its leaves are deeply lobed and the edges are covered in prickly spines. Thistle grows best in dry, barren areas and its flowers can be seen from April through August.

Type

Biennial Broadleaf

Family

Asteraceae

Control

It is important to identify the thistle in its early stages and take immediate action. Applying pre-emergent herbicides is the most effective control method for this weed, as they prevent seed germination. Additionally, post-emergent herbicides that specialize in broadleaf weeds can also be applied to target and control thistle.

Thistle

Velvetleaf

Velvetleaf, also known as buttonweed, is an annual weed that grows in clumps of broad, velvety leaves. This low-growing weed can easily overtake a garden and lawn if not controlled properly. It has yellow flowers with four petals that form at the tips of long stalks which later become seedpods.

Type

Annual Broadleaf

Family

Abutilonaceae

Control

Pulling them by hand is the most effective way to control velvetleaf weed. It is important to pull them before they mature and go to seed, as the seeds can remain viable in the soil up to 25 years. Pre-emergent herbicides such as Treflan or Preen can also be used to prevent velvetleaf from germinating. Additionally, post-emergent herbicides such as 2,4-D, triclopyr, or Glyphosate may be used for existing plants.

Velvetleaf

Wild Violets

Wild Violets are a perennial weed with heart-shaped leaves and small flowers that range in color from purple, blue to white. These weeds grow low along the ground and prefer moist soil conditions.

Type

Annual or Perennial Broadleaf

Family

Violaceae

Control

Wild violets can be difficult to control due to its spreading underground roots. To prevent these weeds from growing, use a pre-emergent herbicide in early spring or fall. Additionally, regularly mowing your lawn will help keep it healthy and strong enough to outcompete invasive weeds like Wild Violets.

Wild Violets

Yellow Wood Sorrel

Yellow Wood Sorrel is a perennial weed that has light green leaves with three leaflets and yellow flowers. This weed grows in damp, shady areas, making it especially difficult to control.

Type

Perennial Broadleaf

Family

Oxalidaceae

Control

To manage yellow sorrel organically, hoe the plant before it blooms and sets seed. Afterward, either discard or leave on a sunny day to dry out naturally. Alternatively, pluck out by hand or cover with an abundance of mulch or soil for faster results.

Yellow Wood Sorrel
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Oliver Wright
Oliver Wright

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