Ralph Waldo Emerson described a weed as “a plant whose virtues have not been discovered.” For those of us less poetically inclined, a weed is any plant we don’t want in our lawn or garden. 

    Surprisingly, only 3% of the 250,000 plant varieties in the world are weeds by virtue of any danger they pose to people, animals, or crops. Far more plants are weeds just because we don’t like them.

    Denver consistently ranks at the top of the most desirable places for people to live — and likewise appeals to weeds that have migrated here from far-off places.

    Here are some of the most unwanted weeds that claim squatter’s rights in the Mile High City:

    Canada Thistle

    This immigrant wins the Ugliest Weed contest hands down because its leaves are covered with threatening and repulsive spines. It spreads quickly and can grow to an intimidating 6 feet if left untreated. The best way to get rid of it is to pull or dig it up. Caution: Use gloves — those spines will give you a nasty sting! Be careful using herbicides because those that kill Canada thistle can also kill grass and other plants.

    Lambs Quarters

    This weed, also known as pigweed, fat-hen, and dirty Dick, is one of the most common in Colorado. You can easily spot it by the powdery substance on the underside of the leaves. It shows up in early spring and spreads quickly. Pull or hoe it up before it matures. To get a head start, use a pre-emergence herbicide.  Lambs Quarters is related to spinach and some gardeners say it’s great in salads — if you’re inclined to eat your weeds.


    This species (pictured above) spreads flat against the ground from a central taproot. Its main threat to lawns is simply taking over space. A single plant can produce 200,000 seeds and those seeds can germinate for years! Pulling it up by hand is the best method, but a pre-emergent herbicide is also an option. Beware, though, purslane is like a zombie. Just when you think you killed it — it comes back! Some folks like purslane for its lemony flavor. It also has the highest content of health-enhancing Omega-3 fatty acids of all the plants in the world!

    Curly Dock

    Drive around the outskirts of Denver and this is the weed you’ll see growing in tall clumps in fields and along the roadside. Unfortunately, you may see it growing in your yard, too. It gets its name because its deep green leaves appear curled or shriveled around the edges. It grows in bushy structures that can reach four feet in height. Digging or pulling up is the most effective method of control, although herbicides work on young seedlings. Seeds left in the ground are known to wait 80 years to germinate! Curly dock is technically edible and has the reputation of feeding the hungry during the Great Depression but its leaves are poisonous to livestock. It does not get five-star ratings from epicureans. 


    This is one of the most dreaded weeds because it spreads from both seed and root as it vines along the ground. Its little white flowers look deceptively like morning glories. Like purslane, bindweed is a zombie weed. Leave just the tiniest bit of living root in the ground and — it’s b-a-a-c-k! Persistent hand-pulling is the best way to get rid of it because any herbicide effective against bindweed will kill all other plants nearby. An alternate method of control is repeatedly pouring boiling water on it until it gives up the ghost.

    There are few quick fixes in the war against weeds. Your best weapons are patience and perseverance. It’s an age-old battle between humans armed with hoes and spades and stubbornly tenacious plants determined to survive and thrive!

    Do you have questions about Denver lawn care? Please visit our Denver lawn care guide page.

    Main image credit: Texas A&M Aggieturf