Northern Colorado! Summer is right around the corner, and the weeds have already started emerging to bask in the hot summer sun! You may have noticed the thistles, knapweed and other unsightly plants starting to pop up all around. This blog post will explain why its important to manage those weeds, and how you could get into trouble for letting them grow!
Summertime: A Weed's Favorite Season
The Back 40 Team
Kill The Weeds, Improve Your Land
There are so many reasons why weed control and vegetation management are so important. Weed control is essential for maintaining healthy ecosystems and protecting the value of land—especially for property owners with livestock or agricultural operations. Weeds often outcompete native vegetation by aggressively consuming water, sunlight, and nutrients, which leads to a loss of biodiversity and can severely degrade habitat for wildlife. For landowners with animals or cattle, the stakes are even higher: many invasive weeds are toxic or unpalatable to livestock, posing serious health risks and reducing the available forage. Additionally, unchecked weed growth can increase fire danger by creating dense, dry fuel beds, particularly in arid or semi-arid regions. Effective weed management helps preserve soil quality, supports native plant regeneration, protects water resources, and ensures that working lands remain productive and safe.
Here's What to Look For
Sometimes it can be difficult to differentiate between weeds and desirable vegetation. With that being said, here is a list of just a couple common broadleaf species you may see when considering Northern Colorado weed control. Keep in mind there are also many other species to look for!
All weed images credited to the Colorado Department of Agriculture website which can be found here.
Canada Thistle
A perennial weed with deep, creeping roots and spiny leaves. Canada thistle spreads aggressively by both seed and root system, making it difficult to eradicate. It can reduce forage availability and is highly competitive with native plants.
Musk Thistle
A biennial weed with spiny leaves and large, nodding purple flowers. Musk thistle thrives in disturbed soils and can grow over 5 feet tall. It spreads rapidly by seed and outcompetes native plants, reducing forage quality and biodiversity.
Diffuse Knapweed
An annual or biennial that produces numerous seeds and has a deep taproot. Diffuse knapweed is known for its allelopathic effects—releasing chemicals into the soil that inhibit the growth of surrounding plants. It reduces forage and alters soil composition.
Common mullein
A biennial plant with a tall flowering stalk and dense rosette of fuzzy, gray-green leaves. Common mullein can reach up to 6 feet in its second year and produces small yellow flowers. It invades disturbed areas and rangelands, reducing native plant cover and creating competition for moisture and sunlight.
Leafy Spurge
This perennial invader has a deep root system and produces a milky latex sap that is toxic to cattle and horses. Leafy spurge quickly dominates pastures and rangelands, outcompeting native vegetation and reducing grazing capacity.
Field Bindweed
A vining perennial with white to pink funnel-shaped flowers. It spreads rapidly through seed and root fragments, tangling around desirable plants and stealing moisture and nutrients.
Some Weeds Could Get You in Trouble!
All weeds are annoying, but noxious weeds are species that are a step up from the other species in importance. In fact, all of the species listed above are classified as noxious! In Colorado, noxious weeds are invasive, non-native plants that pose significant threats to agriculture, native ecosystems, and public lands. The Colorado Noxious Weed Act mandates that landowners are responsible for controlling these invasive species on their property. Failure to manage noxious weeds can lead to serious consequences. Under Senate Bill 24-031, effective August 7, 2024, violations of noxious weed management laws are classified as civil infractions. Landowners found in violation can face civil penalties ranging from $500 to $1,000 per offense. Moreover, each day a violation continues is considered a separate offense, potentially accruing additional fines of up to $100 per day. Unpaid penalties may result in liens against the property, and county attorneys are authorized to seek injunctions to enforce compliance. These stringent measures underscore the importance of proactive weed management to protect Colorado's natural resources and agricultural productivity.
For a full list of noxious weeds that are found in Colorado, and for more information about these species, click the button below to visit the Colorado Department of Agriculture's noxious weeds page
Key Weed Management Techniques
When it comes to managing populations of weeds, it's important to consider which methods of weed control are best for achieving desired results. There are various weed control methods which include mechanical removal, chemical application, biological control, and cultural control. For best results, it is widely recommended to develop a solid integrated pest management plan and utilize multiple methods simultaneously.
One of the most effective methods that gives a person the most direct control over weeds is chemical control. Performing post-emergent herbicide applications in the summer is a key strategy for managing established weeds that have already sprouted and begun actively growing. This method is especially effective against broadleaf weeds and invasive grasses like the species mentioned earlier. Post-emergent herbicides work by targeting the plant’s foliage and are absorbed into the vascular system, disrupting essential growth processes like photosynthesis or amino acid synthesis. When timed correctly—typically when weeds are young, green, and actively growing—these treatments can significantly reduce weed populations and prevent them from setting seed, which is critical for long-term control. Summer applications also allow landowners to spot-treat problem areas without damaging desirable native grasses or forage, helping maintain a balanced plant community and reducing the chance of re-infestation.
Despite being arguably the most effective weed control method, chemical control is also one of the most risky methods, and the hardest to master. While it can be easy to just go to Walmart, buy some Roundup, and go to town on weeds, most people have no idea if what they buy will even work on the weeds they spray! Not to mention, Roundup will most likely kill any native vegetation adjacent to your weeds. Chemical control is a science that takes time and experience to master. There are so many different chemicals and tank mixes and active ingredients for every weed situation, and figuring out the right one can be a nightmare of trial and error and dead native plants. With that being said, if you have a major weed problem that might get you into trouble, it could be worth consulting an expert for your weed control needs.
Skip the Roundup, Call Us!
At Back 40 Land Management, we have years of weed control experience under our belts. From Laramie WY, to Longmont, CO, we have serviced dozens of properties and left countless clients satisfied with control over their weeds. We have deep knowledge of all the noxious species known to reside in Northern Colorado, and sufficient means to eradicate any population on your land while preserving the natural ecosystem. Give us a call or schedule a quote today, and let us knock out your weeds this summer!