Colorado weeds – 15 most common

Once upon a time, in Colorado, there lived a group of wild and rebellious garden weeds. No matter how many times they were plucked or poisoned, they always came back with a vengeance. Gardeners despised them, yet the weeds always found a way to survive and thrive.

These pesky plants were not only the bane of gardeners’ existence, but they also wreaked havoc on hiking trails, roadsides, and just about anywhere they could find a spare patch of soil. Despite their unwelcome presence, these Colorado weeds proved to be resilient and tenacious, much to the frustration of all those who sought to get rid of them.

Let’s explore the 15 most common weeds found in Colorado and what you can do to get rid of them:

Colorado weeds snippet

Table of Contents

Colorado weeds

Name of Weed Family
Bindweed Convolvulaceae
Canada Thistle Asteraceae
Curly Dock Polygonaceae
Dandelions Asteraceae
Giant reed Poaceae
Hairy willow-herb Onagraceae
Japanese Knotweed Polygonaceae
Kochia Asteraceae
Lamb’s Quarters Amaranthaceae
Mediterranean sage Lamiaceae
Orange hawkweed Asteraceae
Purple loosestrife Lythraceae
Purslane Portulacaceae
Quackgrass Poaceae

Bindweed

With its pretty, trumpet-shaped flowers in a shade of lilac, bindweed can be mistaken for the morning glory, but it is actually a climbing vine that can grow wildly out of control. 

Once it wraps around any structure, it can quickly engulf any other plant in its path, suffocating them by depriving them of sunlight. It is known to completely cover other plants and eventually choke them, making it a troublesome weed to deal with. Bindweed seems to thrive better in drier soils, further adding to its aggressive growth.

Type

Perennial

Family

Convolvulaceae

Control

To control the growth of bindweed-infested areas, it is crucial to ensure that the flower beds and garden are watered regularly since bindweed thrives in dry soil. For extensive bindweed infestations, begin by irrigating the area. When bindweed weeds develop, use glyphosate application to treat the area before planting desirable plants. Subsequently, restrict the regrowth of bindweed by utilizing pre-emergent herbicide or mulch.

garden beds Bindweed

Canada Thistle

Canada thistle is a type of weed that is classified as a perennial and is prevalent across regions throughout Canada and the United States. What distinguishes this weed from other types of perennial weeds is its thick, erect stems that feature sharp spines along the edges. Clusters of small, purple-hued flowers grow at the top of each stem on spikes. This weed also has deep, underground roots that spread via rhizomes.

Type

Perennial weed

Family

Asteraceae

Control

Preventing the spread of Canada thistle is the most effective way to control it. Early removal of the plants by pulling or digging can reduce their numbers. In cases of large infestations, herbicides containing 2,4-D can eliminate Canada thistle. Moreover, mowing before flowering can prevent the plant from seeding. Nevertheless, it should be noted that getting rid of Canada thistle completely is a difficult task, so repeated treatments may be required.

Thistle

Curly Dock

A type of broadleaf weed, curly dock grows up to 5 feet in height and produces long leaves with wavy margins arranged in a rosette. The thick, unbranched stem generally has a reddish tint and bears long clusters of flowers that result in dense panicles. The weed seeds are characterized by small wing-like structures and mature into a dark brown color. With taproots that can penetrate deep into the soil, curly dock is most widespread during the spring season.

Type

Perennial

Family

Polygonaceae

Control

Given its ability to tolerate fluctuations in soil moisture, Curly dock presents challenges in terms of eradication. One approach is to weaken the weed by regularly cutting it down during mowing. Digging out the taproot offers another way to control it. However, experts recommend using broadleaf herbicide applications to effectively get rid of this troublesome weed.

Curly dock

Dandelions

Although dandelions are often seen as benign yellow blooms, if they are not managed properly, they can quickly become a troublesome issue. Due to the fact that each seed head can generate thousands of seeds floating on the wind, these plants can be difficult to eliminate. Once they have taken root, they can penetrate the soil several inches deep, and without removing the whole root, their growth cannot be halted.

Type

Perennial

Family

Asteraceae

Control

In order to remove one or two plants, manually removing them is possible, but it’s crucial to ensure that the whole plant, including the root, is being pulled out. Consistently maintaining your garden or lawn is important for preventing dandelions from spreading. If the weed has taken over your lawn, even with preventive measures, seeking assistance from a professional for an effective lawn weedkiller may be necessary.

Dandelions

Giant reed

Giant reed is a tall, perennial grass that can grow up to 6 meters in height. Its dense foliage consists of long, saw-toothed leaves and feathery panicles. It flourishes in uncultivated areas with dry soils and full sun exposure. This invasive weed species has been known to spread rapidly via runners, making it hard to control.

Type

Perennial grass

Family

Poaceae

Control

Since giant reed has an extensive root system and is able to disperse quickly, it can be difficult to manage. The most effective way to remove this weed is by digging up the entire plant, including the roots. However, in cases of large infestations, herbicides containing glyphosate can be used to inhibit its growth. Additionally, mowing and burning are other tactics that can help contain giant reed in an area.

Giant reed

Hairy willow-herb

Hairy willow-herb is an erect, perennial weed with a thin stem and small leaves growing in whorls of three or four. The triangular-shaped leaflets have edges that are hairy and serrated. This weed produces long spikes made up of numerous pink to purple flowers during its blooming period from June to September. It can be found in fields, meadows, forest edges, and wastelands.

Type

Perennial

Family

Onagraceae

Control

Given the weed’s ability to self-seed, it requires a consistent approach for eradication. One way of managing hairy willow-herb is by mowing before it has a chance to flower. In cases of large infestations, herbicides containing 2,4-D or triclopyr can be used. However, since the weed is fast-growing and long-lasting, multiple applications may be necessary for effective control. Repeated treatments may be required.

Hairy willow-herb

Japanese Knotweed

Identified by reddish-purple shoots and white flowers blooming from pink buds, the Japanese knotweed is a destructive weed species that can grow through buildings, piping, cables, and foundations, causing extensive damage to the property. It blooms entirely during late summer and early autumn, and controlling it is a significant challenge. Eliminating these plants requires specialist care as the weed is persistent and challenging to manage.

Type

Perennial

Family

Polygonaceae

Control

It is advisable to consider professional assistance to effectively manage this weed. To prevent the weed from multiplying, herbicides approved for this purpose can be sprayed or injected into its stems. However, despite the treatment administered, it typically requires a duration of three years to fully control the growth of this weed.

Japanese Knotweed washington

Kochia

Kochia, also known as fireweed, is an erect and fast-growing summer annual weed. It has hairy, light green to red stems with small leaves that have serrated edges. The plant produces tiny yellowish flowers in cylindrical clusters at the tips of its stems. These plants are generally found in dry areas such as roadsides, pastures, grain fields, and lawns.

Type

Annual weed

Family

Asteraceae

Control

Kochia can be effectively eliminated through the use of glyphosate-based herbicides. However, it is important to note that sometimes multiple applications are necessary for complete control. Another option is physical removal, which includes mowing and tilling.

For long-term control, it is also recommended to introduce competitive crop species in the area as they can outcompete the weed. In any case, consulting a professional for an effective lawn weedkiller may be necessary.

Kochia

Lamb’s Quarters

Lambsquarters is an annual weed that has a small, white flower and a low to medium-growth habit. It commonly grows in gardens and lawns and can rapidly spread if not managed. Its leaves are diamond-shaped, with a smooth upper surface and whitish underside. The weed produces small greenish-white flowers that are grouped together in clusters.

Type

Annual Broadleaf

Family

Amaranthaceae

Control

To effectively manage this weed, you may want to consider using selective broadleaf herbicides such as 2,4-D or dicamba (Weed Master). Another option is to physically remove the plant, but be sure to remove all parts of the plant, including the roots.

Lambsquarters

Mediterranean sage

Mediterranean sage is a perennial weed that has grey-green foliage with small white flowers and pointed leaves. This weed has a deep taproot, making it hard to remove manually. It typically grows in dry, sunny areas and produces an abundance of small seeds that can spread easily by wind or other methods.

Type

Perennial

Family

Lamiaceae

Control

The best way to control Mediterranean sage is with a pre-emergent herbicide, as it can help prevent the weed from germinating in the first place. If you choose to use an herbicide, be sure to follow the label instructions carefully. Additionally, physical removal may be used for small, isolated patches of the weed. For larger infestations, it is recommended to consult a professional.

Mediterranean sage

Orange hawkweed

Orange hawkweed is a perennial weed that has a low to medium growth habit and produces orange flowers with yellow-tipped petals. It generally grows in sunny areas and can spread quickly, forming dense mats of foliage.

Type

Perennial

Family

Asteraceae

Control

Orange hawkweed may be managed using chemical control methods such as glyphosate-based herbicides. Additionally, physical removal may be used to get rid of small patches of the weed. For larger infestations, a professional may need to be consulted for an effective lawn weedkiller. Furthermore, introducing competitive crop species in the area may help prevent the further spread of this weed.

Orange hawkweed colorado

Purple loosestrife

Purple loosestrife is a perennial weed that has tall stems with bright purple flowers. It is often found growing in wetlands and ditches, along roadsides and riverbanks, and in other moist areas. This invasive species can quickly take over an area and form dense stands that are difficult to remove manually.

Type

Perennial

Family

Lythraceae

Control

Purple loosestrife may be managed with herbicides such as dicamba, triclopyr, or glyphosate. It is important to read the instructions carefully and follow them when applying any chemical control methods. Physical removal can also be used for small patches of this weed, but it is important to ensure that all parts of the plant are removed, including the roots. Introducing competitive plants in the area may also help reduce its spread.

colorado

Purslane

Purslane, also known as Portulaca oleracea, is a leafy green vegetable that boasts red stems, small verdant leaves, and a water content of 93%, making it both delicious and refreshing.

Despite being deemed a weed by some, this healthy and nutritious plant can be consumed in various raw or cooked dishes under other monikers, such as pigweed, fatweed, little hogweed, and pusley. In fact, it packs more omega-3 fatty acids compared to any other leafy vegetable, and is also a great source of vitamins B and C, iron, magnesium, calcium, and potassium.

Type

Annual Broadleaf

Family

Portulacaceae

Control

You can use manual extraction or chemical control methods to eliminate purslane. Conserving soil moisture through rainfall or irrigation can be helpful in reducing its spread. Using broadleaf herbicides such as Weed Master or 2,4-D is another effective method of controlling it.

Purslane

Quackgrass

Quackgrass is a type of perennial weed that grows to approximately two feet in height and has v-shaped leaves. It produces small flowers in the summer which are white in color. Its ability to spread rapidly is due to the creeping roots that can generate new shoots in other areas. Quackgrass thrives best under moist soil conditions and will typically wilt once conditions become too dry.

Type

Perennial grass

Family

Poaceae

Control

The most effective way to control quackgrass is by preventing its growth. It is important to remove any sprouting quackgrass before it spreads its seeds. Applying a pre-emergent herbicide is also an option to stop new quackgrass plants from emerging.

quackgrass

Spurge

Spurge is a prevalent weed species that grows during the warm season and is typically found in container nurseries. It features greenish-white flowers, and when its leaves or stems are damaged, they emit a milky sap.

The most common types of spurge are the ground spurge and spotted spurge, which have almost identical characteristics, such as having prostrate to ascending stems with round or oblong leaves. This weed species grows widely in grasslands, pastures, roadsides, and prairies and has the ability to survive in various types of soil.

Type

Perennial

Family

Euphorbiaceae

Control

One can effectively remove a small patch of spurge by hand-pulling it, but prevention is the primary method of dealing with spurges because controlling them is challenging once they have taken root. Post-emergent herbicides are available for controlling spurge invasions in lawns and gardens.

Spurges
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Oliver Wright
Oliver Wright

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