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Introduction

The Douglas County Invasive Weeds Management Program exists to prevent, eradicate and control invasive weeds through education and public land management. Invasive weeds are non-native and aggressive plants that can replace natural vegetation and contribute to wildfire risk. Controlling their growth is key to fostering healthy ecosystems throughout Douglas County. This virtual environment is designed to help residents identify common invasive weeds, learn best practices for weed management, and connect with resources for further invasive weeds information and support.

The educational information provided in this resource is courtesy of the Colorado Department of Agriculture.

Growth Pattern

In its first year, has circular bursts of leaves stemming from a central point. In its second year, a dense bush of long stems branches out with a single flower at the end of each branch.

Leaves

Wavy and oblong shape with a fuzzy texture that gives them a gray-green appearance.

Flowers

Thin oval-shaped bulb covered in thorns with a tuft of feathery, white petals on top — similar to a thistle flower in shape.

Height

2-4 feet.

Additional Information >>

Growth Pattern

Begins as a circular burst of leaves stemming from a central point (known as a rosette). Once mature, the central stem produces smaller branches ending in multiple flowers (one to five). Leaves are denser toward the base.

Leaves

Bright green, wavy and oblong with spines and a fuzzy underside.

Flowers

1-centimeter, spineless bulbs with a tuft of feathery, purple petals on top.

Height

2-4 feet.

Additional Information >>

Growth Pattern

Starts with a circular burst of leaves stemming from a central point. In its second year, it has a thick, spined central stalk with spined branches ending in a large, drooping flower with smaller flowers below it on the branch. Leaves are denser toward the base.

Leaves

Dark green, waxy, thin shape with jagged edges and spines.

Flowers

Up to 2.5 inches in diameter with a flat bulb covered in long thorns with a disk of feathery, purple petals on top.

Height

Flat in the first year, up to 6 feet tall once mature.

Additional Information >>

Growth Pattern

Grows with a thin stem (or stems) covered in thin leaves from the base to the top — similar to a rosemary leaf structure. Once mature, it has several long stems — woody at the base and green at the top with a clump of multiple blooms at the end. The stems are covered in thin, connected leaves throughout.

Leaves

1-2 inches, light gray-green with a thin, straight, needle-like appearance.

Flowers

Bright yellow petals with a deep yellow to orange center. The petals resemble a snapdragon flower with a long tail (spur) on the bottom.

Height

1-3 feet.

Additional Information >>

Growth Pattern

Seedlings have smooth, pale green shoot(s) covered in thin, wispy leaves connected directly from the base to the top. The main stem of the mature plant ends in a cluster of blooms with additional blooms protruding below the main cluster.

Leaves

Narrow, linear, pale green leaves with a pronounced central vein.

Flowers

Yellow-green in color and resembling an upside-down bell as it opens. Fully open blooms are disks of yellow-green petals with a cluster of smaller petals in the center.

Height

1-3 feet.

Additional Information >>

If you don't see the invasive weed you are looking for, reach out to the Douglas County experts by calling 303-660-7480 or visiting douglas.co.us/public-works/report-a-problem.

Environmental Impacts
of Invasive Weeds

Invasive weeds are moving into our valued ecosystems and displacing our native plants at an alarming rate. When the plants that wildlife uses for food, shelter or nesting are gone, the wildlife will leave the area. Invasive weeds also impact our valuable agricultural lands and commodities. When resources are not available for their desired use, it takes more land to raise the same number of cattle or bushels of wheat. Because of these factors, they have been declared by the state, local and federal governments to be undesirable, and their control, containment and eradication are required by law under the Colorado Noxious Weed Management Act.

Managing Invasive Weeds

Invasive weed management requires multiple methods throughout the year to prevent, eradicate and control unwanted weeds. An effective weed management system integrates two or more of these methods into a plan of operation:

  1. 1. Cultural methods promote the growth of desirable plants through fertilization, irrigation and planting of high-quality, desirable plants. This allows plants to outcompete invasive weeds and inhibit the establishment of new weeds.
  2. 2. Mechanical measures disrupt weed growth by mowing, pulling, hoeing and burning. The timing of these efforts is critical to address weed growth before they go to seed and start new infestations.
  3. 3. Biological controls through the introduction of host-specific predators from the weed's native country and the use of animals such as sheep and goats reduce the vegetative growth of weeds.
  4. 4. Herbicides or chemical controls are most effective when used in conjunction with other management techniques to address current invasive weeds and prevent future infestations. Always read and follow label instructions when applying herbicides.

County Resources for
Private Property Owners

Douglas County's goal is to help residents learn how to identify invasive weeds and control their spread. To do this, county staff will come to your location and help you develop an invasive weed control plan with a written procedure outlining the most effective way to control invasive weeds on your property without damaging desirable vegetation.

This program is available to any property owner in unincorporated Douglas County. If we manage your snow, we're happy to help you manage your weeds. From suburban backyards to large acreages, all residents are welcome. Staff will observe the invasive weeds on the property and determine the best management methods for maximum control. The landowner/resident will be given an individual weed management plan that includes the identification of each weed, control methods available for treatment, herbicide recommendations, optimum spraying times and short/long-term goals for infestation control. To schedule a consultation, call 303-660-7480.

More Information

To learn more about invasive weeds in Douglas County, please visit douglas.co.us and search “invasive weeds.”

For information about specific weed species and identification, please visit the Colorado state website at ag.colorado.gov/conservation/noxious-weeds.

To schedule a consultation, call 303-660-7480 or visit douglas.co.us/public-works/report-a-problem.