Noxious Weeds


WHEN:  Every Friday, 8 - Noon, LAST GIVEWAY IS THIS FRIDAY, SEPTEMBER 29. You must bring your own hand held or backpack sprayer (0-5 gallons).  We cannot fill any other kind of container.

WHERE:  469 E Topaz Av, Granby, CO (4th & Topaz)

Dates for Give-Aways

For information on what to do with old or leftover herbicides or other household hazardous wastes, please click HERE

WHERE'S THE CREW:  The week of September 25, Hwy 125; Hwy 40 south of Granby; county owned gravel pits throughout the county.  Schedule is always subject to change at any time due to unforeseen circumstances and/or weather.


Scentless chamomile, Canada thistle

Scentless chamomile is an annual species, each plant lives one year and comes from seed only.  Annuals germinate throughout the growing season, flowers are small white daisies with a raised yellow button center.

Canada thistle is a perennial root spreader.  The root system can be up to 20 feet deep in the soil!  Pulling generally will not work unless it is a new infestation you might have a chance, due to the extensive root system.  When you break off roots underground, it is spurred to make more.  A combination of herbicide and grazing works very well and can bring large populations under control in a few years.  Canada thistle generally starts blooming in late July through September.  

The aim of the Noxious Weed Program is to control noxious weeds, the non-native aggressive invaders that replace native vegetation, altering native ecosystems, reduce agricultural productivity, cause wind and water erosion and pose an increased threat to communities from wildfire. We do this by preventing the introduction of new invasive species; eradicating species with isolated or limited populations and containing and managing those invasive species that are well-established and widespread.  Grand County Division of Natural Resources identifies and manages State-listed Noxious weeds on all County Rights-of-Way, County properties and we partner with local offices of the USFS and BLM for invasive species control as required by State law. We do not work on private property or private roads.  

The term, "Noxious," is a legal term and the Colorado Noxious Weed Advisory Committee assists the Colorado Department of Agriculture in determining if a non-native plant is invasive enough in CO to warrant listing for control. 

Although there are over 80 species of noxious weeds on the Colorado list, Grand County has 26 species for which we manage.  Grand County Noxious Weed List

Noxious weeds are a direct and growing threat to the native environment of Grand County and the west.  They threaten the very reasons we live, work, and recreate in Colorado and all Colorado landowners are responsible for controlling noxious weeds on their property.  

Noxious weeds are non-native plant species that have been introduced into an environment with few, if any, natural biological controls, giving them a distinct competitive advantage in dominating and crowding out native plant species, altering plant diversity and ecosystem integrity. They are aggressive, spread rapidly, possess the ability to reproduce profusely, and resist control. Pollinators are pushed to pollinating more of the non-native species instead of the native species’, furthering their ability to displace native flora and negatively affect wildlife habitat and native ecosystems.  

Thistles of Colorado booklet; There are "good" thistles!  This booklet covers the most common native thistles and the most common non-native, invasive thistles.

Establishment & Control

Noxious weeds become established in soils disturbed by a variety of activities such as construction, motorized vehicles, road maintenance, recreation, improper livestock grazing, and natural disturbances such as a fire. Noxious weed seeds are transported to new sites in numerous ways such as wind, water, tires, people, as well as on or in wild and domestic animals.

Grand County Division of Natural Resources (DNR) operates under a directive from the Colorado Department of Agriculture to control and reduce the spread of noxious weeds in Grand County. This includes all county-owned property, road rights of way, and public lands. Grand County DNR is also focused on providing information and assistance to private landowners to help control the spread of noxious weeds.

Noxious Weed Guide

The Middle Park Conservation District, in partnership with Grand County Natural Resources, recently produced a Grand County Noxious Weed Guide that is specific to the Noxious weed species found in Grand County and methods for control as well as information about prevention, re-seeding, and calibrating your sprayer for proper herbicide application.

Hard copies are available at our office; NW Ranch Supply in Kremmling; the Conservation District office in Kremmling; and a few other local businesses around Grand County.


We have 5 lb bags of short mix grass seed ($55) and 1/2 lb bags of wildflower seed ($20) available for sale.

Click here for more information about these mixes.  We also can get the following mixes:  Grass Seed Available

More Information

Noxious Weed Control Partnerships

  • Bureau of Land Management
  • Colorado Department of Agriculture
  • Colorado Department of Transportation
  • Colorado Parks and Wildlife
  • Colorado State Land Board
  • Colorado Weed Management Association
  • Grand County Division of Natural Resources
  • Habitat Partnership Program
  • Middle Park Soil Conservation Service
  • Natural Resource Conservation Service
  • United States Forest Service