Be aware of poison hemlock this spring

poison hemlock flower
Poison hemlock is one of the most toxic plants in the area. Infestations of this plant and wild parsnip are flourishing in southern Ohio. (Photo by Joe Boggs, OSU Extension)

Late frosts are hard on emerging annual plants, such as corn, soybeans and vegetable crops, but it hasn’t slowed the growth of hearty weeds, such as poison hemlock.

Poison hemlock is a biennial weed that is toxic to livestock and people if ingested, making it dangerous in the edges of pasture fields and hay fields throughout the U.S. Poison hemlock is commonly confused with Queen Anne’s lace or wild carrot by people who see it when passing by, due to the white clusters of flowers it produces.

Hemlock has a more rigid stem with purple spots, and leaves that are “fern-like,” according to Weeds of the Northeast, by Richard H. Uva, et al.


According to the U.S. Department Agriculture’s Agricultural Research Service, poison hemlock toxicity in livestock, equine and domesticated animals presents with respiratory distress that may lead to seizure-like activity and death. Some research even suggests birth defects occurring in offspring of mothers that ingested poison hemlock while pregnant.

The best cure for poison hemlock toxicity is prevention. Treating this problem weed is essential to keep livestock and domesticated animals safe, as well as protecting yourself and your family.


According to the 2018 Ohio State University Extension Weed Control Guide, poison hemlock is a broadleaf and is susceptible to being controlled by Crossbow and Remedy Ultra. Both herbicides generally are more effective with surfactants, which act as an agent that helps chemicals stick to the plant. Be sure to read the herbicide label for any chemicals you plan to spray for details on grazing and mowing restrictions, as well as handling and safety precautions.

Poison hemlock is a dangerous weed that, if it is allowed to get a foothold in the edges of your fields, should be dealt with swiftly and effectively. Effects of ingesting this weed include respiratory failure and death. Be mindful and ready to act on problem weeds before they become deadly.


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Jessie Radcliff is the agricultural and natural resources technician for Noble Soil and Water Conservation District. She can be reached at or 740-732-4318.


  1. Early this spring I saw a plant that looks like poison hemlock, but I’m not familiar with identifying poisonous from benign, except for the most common. Now I’m wondering if what I saw in our yard was poisonous hemlock or queen Ann’s lace, and it’s too late to know now as the plant was mowed down by my husband. Guess we will have to keep an eye out for this stuff.


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