11 Different Types of Weeds in Colorado With Pictures

Now that summer is here, most of us are planting our gardens with our favorite fruits, vegetables, and herbs. Growing a garden can be a very peaceful activity, but what if you need to pay special attention to invasive plants? What if you see plants that don’t resemble the fruits or veggies you are growing or are familiar with? Well, then maybe you are looking at a weed.

Weeds are common to be seen in gardens across the US. In addition, Colorado is known for harboring noxious plants during the year’s warmer months. Plants not native to the country but primarily from Europe or Asia are referred to as noxious weeds.

These weeds have either unintentionally or intentionally migrated from their native areas and are now growing abroad. These plants benefit from the absence of the pests, maladies, and predators that would typically control them in other countries. But this is also why these weeds spread quickly and are difficult to eradicate.

This article will concentrate on the most frequent noxious and invasive weeds in Colorado.

What are Weeds?

The word “weed” is one that every gardener has heard. However, few of them are familiar with their technical description. So here it is.

A weed is not a specific species of plant but any unwanted, wayward, or unintentionally planted plant. Botanists also claim weeds are plants whose benefits are still not recognized. In addition, weeds are aggressive, destructive, heavy spreaders and obstruct human activities like farming and gardening.

Fun Fact: Marijuana is not the real “weed.” Although the name is widely used to describe this plant, it is the hippiest slang referring to marijuana and has nothing to do with the noxious, invasive, and undesired plants we are dealing with as weeds.

Also Read: 12 Most Common Weeds in Virginia With Pictures to Spot in Your Garden

Are Weeds Really Bad?

Do you enjoy spending a hot morning or afternoon stooping to pluck weeds? Or is it more worthwhile to use herbicides than digging fresh holes to grow healthy plants? If you said a resounding NO, weeds are truly bad, but not in every case.

By its definition, weeds are undesirable plants. Gardeners may frequently experience sleepless nights due to weeds. If not contained, these are ferocious spreaders and can invade your landscape. Weeds have the power to not only suffocate good plants nearby but also to deplete the soil’s nutrients, lowering crop yield. Weeds may ruin the appearance of your garden as well.

Weeds are not inherently evil, despite their negative image. In reality, some weeds have a pleasing appearance, and most serve important ecological purposes. In addition to attracting birds and helpful predators, weeds deter insects, prevent erosion, loosen up hard soil, and have other advantages.

However, you must concentrate on stopping them from going to seed if you do not want to give weeds a special place in your garden. It is the best strategy to limit their emergence and spread. Keep in mind that every plant in nature contributes in some way to the functioning of the ecosystem. We determine how desirable they are based on how we connect with them.

11 Common Weeds to be Found in Colorado with Pictures

These are the most common weeds in Colorado. Additionally, we have included pictures of each weed for your reference. Weeds have been ranked according to how frequently they are found in Colorado.

1. Cypress Spurge

Cypress Spurge
ToxicityYes, This plant has several irritants

One of the US states where this weed is recognized as harmful is Colorado. This weed can easily intrude on local species’ habitats and is known to harm cattle and other animals, particularly horses. However, there are no known detrimental consequences of Cypress Spurge on sheep.

One of the hardest weeds around, it can be quite challenging to eliminate totally. Cypress Spurge grows best in dry, well-drained soils in full sun but does not get deceived, as this weed also thrives well in poor soil. In addition, this weed is tough by nature, strong against pests and diseases, and a voracious spreader.

2. Knotweed

EdibleYes, It also has medicinal uses
Other Common NamesPersicaria, Fallopia, Japanese knotweed, Reynoutria japonica

Invasive Asian-native knotweed is classified as a Class B noxious perennial weed. Knotweeds, frequently found next to roads and riverbanks, can cover your yard in a thick carpet if left unchecked. This plant can reach a height of 16 feet, and in the late summer, it also bears clusters of tiny white to pinkish flowers.

Knotweed is a prolific spreader and has deep roots and rhizomes. In fact, knotweed can grow through the foundations of buildings. Despite being invasive, knotweed is employed to produce medicine. This plant has effectively treated conditions including bronchitis, cough, sore throat, and other similar conditions.

3. Myrtle Spurge

Myrtle Spurge
Other Common NamesBlue spurge, Broad-leaved glaucous-spurge

Originally from Southeast Asia and Europe, myrtle spurge is an evergreen perennial. It is a succulent plant that blooms from March to May with yellow-green flowers. This weed is classified as noxious, which means that it was brought to Colorado knowingly or unknowingly and is not indigenous to the area.

Myrtle Spurge is a rapidly spreading weed since it has no natural enemies that can stop it from growing. However, this weed has lovely, trailing fleshy stalks that resemble succulents. The plant may shoot seeds up to 15 feet and develops from a taproot.

Myrtle Spurge prefers open spaces, including fields, grasslands, gardens, and roadside locations. Despite the fact that they are lovely plants, you won’t want this weed to spread and flourish in your home if you have a yard with vegetation.

4. Lambs Quarters

Lambs Quarters

Despite being considered a weed, some regions of the world unexpectedly grow Lamb’s Quarter, such as Northern India, where it is known as bathua (an edible green leafy). This weed is also called goosefoot, wild spinach, melde, and fat-hen.

It is edible, although it is regarded as a weed in Colorado. Lamb’s Quarter will start showing up in your yard in the early spring. If this weed doesn’t annoy you, you can grow Lamb’s Quarter as wild spinach.

But keep in mind that if you leave this plant alone, it will spread throughout your garden and shadow your vegetables as it grows up to 150 cm tall. Therefore, we advise pulling out the entire plant when you are finished harvesting Lamb’s Quarter as an edible green leafy.

Doing so would restrict this weed from taking over your garden. Before this weed matures and develops a strong root that is challenging to dislodge, make sure you hand weed it repeatedly.

You May Also Read: Weeds in NJ: Identify the 12 Commons Weeds in New Jersey With Pictures

5. Purslane

Purslane grass weed
EdibleYes, But it should not be consumed by those with kidney issues or uric acid problems

Purslane is another edible weed on our list. This weed has a lemony flavor and is succulent and high in Omega 3 fatty acids. This tropical perennial can yield over 200,000 seeds and thrives best in USDA Zones 10 and 11.

Purslane is a weed that can be eaten raw or lightly tossed and is typically regarded as an alien plant brought to North America during the pre-Columbian time. Repeated hand weeding is one of the best techniques to control the spread of the Purslane.

6. Mediterranean Sage

Mediterranean Sage

In the US, Mediterranean Sage is classified as a “List A” noxious weed and was brought in by infected alfalfa seed. Despite being a native of Eurasia, Mediterranean Sage is a biennial or short-lived perennial weed in Colorado, growing up to 3 feet tall and wide.

A mature Mediterranean Sage plant may yield a staggering 100,000 seeds, and from June to August, you can discover clusters of yellowish-white flowers on these bushes.

In grasslands, dry pastures, woods, along roadsides, and on riverbanks, this weed is regarded as problematic. One of the finest natural methods for removing Mediterranean Sage plants is through hand weeding. Make sure to remove all of the roots or at least 2-3 inches of the rhizome while hand-weeding.

7. Purple Loosestrife

Purple Loosestrife
EdibleIt is considered edible

Isn’t it lovely to see a big field of purple flowers swaying to the breeze’s beat? We’re sure that it looks satisfying. But what if those plants with purple blooms quickly invade your entire yard, displacing other plants? Does that sound awful? But Purple Loosestrife, an invasive weed in Colorado, accomplishes this.

This weed was brought to the US as an ornamental plant that escaped into the wild, where it can quickly engulf the entire growing area. To our amazement, a mature Purple Loosestrife may also produce a staggering three million seeds annually.

That is truly astounding. Worse, seeds can survive in the soil for up to 20 years before they become rotten. So, use mechanical weed control methods like hand or shovel weeding anytime you spot the first Purple Loosestrife plants. Herbicides containing glyphosate can also be used to control this weed better.

8. Curly Dock

Curly Dock
EdibleYes. However, before using young leaves in any dish, they must be carefully cooked to remove the oxalic acid. Leaves can be added directly to salads in a moderate amount also. That said, once the plant reaches maturity, it becomes too bitter to eat.
ToxicityYes, if consumed in excessive amounts.

The buckwheat family plant known as Curly Dock, also known as Curled Dock or Yellow Dock, is frequently seen throughout Colorado. This weed is edible and rich in vitamins A and C. Young leaves are palatable, but as the plant ages, the leaves turn bitter and unfit for consumption. Curly Dock has a deep and powerful taproot that allows it to thrive in various environments, including meadows, roadside ditches, and the edges of forests. Once mature, it may be challenging to completely eradicate Curly Dock by hand weeding because it will reappear from roots that were left in the ground. However, you can undoubtedly dig up the entire plant with a shovel.

9. Kochia

Family Amaranthaceae
EdiblePalatable when mixed with hay and other forages

Kochia, sometimes known as Kochia scoparia, is a weed not native to the US. If left unchecked, Kochia, abundant in all western states, can reach heights exceeding 5 feet. This weed may emerge, develop quickly, and tolerate various soil conditions, making it problematic.

This weed is frequently discovered around roadsides, ditches, etc. The good news is that because the weeds have a shallow taproot, they are simple to uproot while young. Early spring is the optimum time to pull up Kochia because that is when it first starts to emerge.

Although Kochia does not currently have any biological control agents, the growth of the weed can be regulated with pre-emergence and post-emergence herbicides.

10. Dandelion


Dandelions are a familiar sight to the majority of us. Dandelions are part of a wide genus of blooming plants, but they are regarded as weeds because of their propensity to spread aggressively. Once dandelions take hold, getting rid of them permanently becomes very difficult.

The good news is that dandelion roots, leaves, and blooms are edible. But keep in mind that dandelion pollens could trigger allergies. Therefore, use caution when handling this plant. It produces yellow flowers that develop into fluffy seed heads carried by the wind and have broad, green leaves.

To safely remove dandelion plants, use a spade or shovel to dig up as many roots as possible.

11. Canada Thistle

Canada Thistle
ToxicityProduces nitrate and can be toxic to horses

Canada Thistle is a perennial flowering plant. Despite being seen as a weed, Canada Thistle attracts pollinators. Hoverflies and other pollinators are drawn to its nectar. Canada Thistle can grow in various settings, such as pastures, woodlands, mining sites, and roadside ditches.

Due to its extensive root system, this weed can easily spread voraciously far away from its original position. If not controlled, Canada Thistle can seriously harm the health of the wildlife and crop output.

Here, you should know that this weed can harm horses as it produces nitrate. So, a systematic strategy should be strictly used to limit Canada Thistle’s growth. Hand weeding, once the first plant appears, is mostly advised. Post-emergence herbicides can also be applied in the spring and summer in addition to this.

The Takeaway

So there you have it—our opinion of the most common weeds in Colorado. Before we wrap up this essay, we’d want to emphasize that even weedy plants have a vital function to play in maintaining the environment.

Nevertheless, weeds are ruthless dispersers. If not contained, they have the potential to infiltrate any area and destroy both plants and animals.

Therefore, if you are specifically interested in growing a certain weed in your garden, we advise you to start a systematic process to get rid of these plants as soon as you spot them.

About Jennifer Igra

Growing up in Brooklyn, New York City known for it’s green gardens. Jennifer, a 30 year old gardener and green living fanatic started Igra World to share her gardening journey and increase gardening awareness among masses. Follow Igra World to improve your gardening skills.

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