Vail Valley weeds: Careful removing poison hemlock |

Vail Valley weeds: Careful removing poison hemlock

Gregg Barrie
Vail, CO Colorado
Pedro Tenorio-Lezama/Bugwood.orgVail weeds: The lacy white flowers of poison hemlock resemble Queen Anne's lace. Photo by

VAIL, Colorado –Poison hemlock, a highly poisonous plant, is found in patches throughout Colorado’s Vail Valley and is targeted by Eagle County’s municipal and county Noxious Weed Management Programs.


• A tall, airy plant with lacy white umbrella-shaped flowers from June to July

• Biennial, with shiny fern-like leaves growing from 4 feet to 10 feet tall

• Stems are characterized by purple spots

• First years foliage resembles that of a wild carrot

• Leaves have a musty odor

• Tends to grow in wet areas


• All parts of the plant are poisonous and should be handled with care. This is believed to be the plant that killed Socrates.

• Wear gloves when handling it. Don’t put it into the compost because the dead stalks can remain poisonous for two or three seasons. Don’t incinerate it (don’t inhale the smoke). It has even been recommended to discard gloves after handling this plant.

• As a biennial, this plant can be eradicated by not allowing it to go to seed.

• Plants can be pulled as soon as they are big enough to take hold of, but before they flower and produce seed. The crown must be completely removed so that the plant does not re-flower. Poison hemlock can be mowed to prevent flowering and seed production, but this will only be a short-term solution as it is sure to produce more flowers.

• A biological control agent, the poison hemlock moth, has been tested in Snowmass Village. This European bug eats only poison hemlock and has been keeping the plant in check in Europe for centuries.

• Chemical control options include gyphosate, which can be spot sprayed on basal rosettes, applied in early spring or late fall when most desirable vegetation is dormant. Other options include phenoxy herbicides, such as 2,4-D or dicamba, applied in early spring or late summer/fall.

For more information on these plants and the weed management programs in Eagle County visit or Or call the Eagle County Weed and Pest Department, 970-328-3540, the town of Vail Department of Public Works 970-479-2158, or the Eagle County Extension Office 970-328-8630.

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