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1. How did noxious weeds get here?

Most noxious weeds come from Europe or Asia. Seeds or plant fragments are unknowingly transported to new areas where they are spread and grow into plants. Many noxious weeds have been sold as ornamental plants that have escaped home gardens and spread into the wild.

2. What are noxious weeds?

Noxious weeds are plants growing outside their natural habitat. These non-native plants become problems because they are invasive and can spread quickly in a variety of ways.

3. What are the weed lists?

The state Noxious Weed List is divided into four categories.

• List A - weeds identified by the state as uncommon and are required to be eradicated. Eradication means the complete elimination of the plant prior to reproduction.
• List B - weeds identified as having varying populations throughout the state. Eradication zones may be established in areas where the weed is uncommon. In areas where the weed is more common, control and population containment is required.
• List C - weeds that are common throughout the state that property owners are encouraged to control.
• Watch List - weeds whose invasiveness have not yet been determined but are new to the state and have been shown to be invasive elsewhere.

4. What do I do if I have one of these weeds?

Once you discover a noxious weed on your property, it is important to act. An integrated approach, including one or more control techniques, will provide the best chance for success. Remember, weed control is a process that requires patience and repeated efforts; what works to control one weed might not work on another. Review the Noxious Weed Information page for additional assistance.

5. What does the law say about noxious weeds?

The Colorado Noxious Weed Act (CRS 35-5.5) was passed in 1990 and updated in 2003. This law requires all public and private landowners in the state of Colorado to maintain control over certain noxious weeds. The law addresses the severe threat these non-native plants pose to native plant communities, wildlife habitat, agricultural lands and property values within the state.

Landowners that have noxious weeds on their property are required to control them.

6. Whom do I contact about tall weeds?

Planning and Zoning is the department that handles tall weed complaints.

7. Why are noxious weeds a problem?

Noxious weeds are often pretty, but their effects are not. The absence of natural enemies in the new environment means weeds can spread uncontrollably, vastly reducing the number of native plants. This affects wildlife that depends on native plants for food; therefore, an increase in noxious weeds results in decreased native wildlife populations.