How to get rid of poison hemlock for good - Farm and Dairy (2022)

How to get rid of poison hemlock for good - Farm and Dairy (1)

I thought poison hemlock awareness was increasing significantly, but then reality hit me.

While driving back from Cincinnati to Marietta, with my family, we stop to explore the Serpent Mound in Peebles, Ohio. While making our way there, we saw a farm selling hay, so I stopped to ask how much since I was running low this year due to the lack of forage production at the beginning of the growing season.

As I was pulling up to the house, I couldn’t help but notice all the 1-foot poison hemlock plants, so I jokingly asked the farmer if he was in the business of growing poison hemlock or milking cows.

He quickly replied, “Well, I guess both.”

After pointing it out and describing the effects to him, he mentioned that his cows were “acting funny” the other day and thought they got into something. He had no idea this invasive plant was on his farm and quite frankly, never gave it much thought.

It can kill

Poison hemlock is highly toxic to humans and livestock when ingested — either in its vegetative growth stage and when dried.

(Video) Poison Hemlock — The Plant We Love To Hate

Typically, grazing animals will avoid poison hemlock because of its unpalatable taste unless there is little other feed or forages available or when it’s consumed through hay.

When consumed, poisoning symptoms appear rather quickly which includes: bloody feces, vomiting, paralysis, trembling, loss of coordination, pupil dilation, coma and eventually death from respiratory failure.

How to control

Poison hemlock can be controlled quite easily. I completely eradicated it from my farm in two years using nothing but a machete, a little patience and botany.

In the summer of 2015, the county township asked if they could spread soil along my property to help build-up and stabilize the road since the road was 4-5 feet higher than my pasture.

At the time, I said yes, but I did not realize the soil source came from road ditches that the county had been clearing.

When spring of 2016 rolled around, the amount of junk weeds that appeared along my property was heartbreaking, and, of course, poison hemlock was among the junk weeds.

Since poison hemlock is a biennial (a plant that takes two years to grow from seed to fruition and die — this is where botany comes in to play), I used a little patience and waited for the plant to flower.

(Video) How to Get Rid of Poison Hemlock? 4 Options for Removal

One week after the plants flowered, I simply chopped them down at the base and discarded the plants over the hill and away from livestock. By cutting the plant down after flowering, I eliminated its potential to produce more seeds.

At this time, the plants did not have enough reserves to shoot up another flowering stalk.

In the spring of 2017, I had a few more plants bolt up (leftover 2015 seeds that germinated in 2016), so I simply repeated what I did the year before to control it.

Now in 2018, I did not have a single plant bolt up and all it took was patience, botany and a machete.

Of course, if this plant has been present on your property for a while, it may take you up to 3-5 years to completely eradicate and exhaust the soil’s seed bank. Poison hemlock seeds are viable for only 3-5 years.

What does it look like

The first step to controlling poison hemlock is being able to recognize the plant. Right now is a great time to identify the plant, because currently, poison hemlock is somewhere between 2 to 5 feet — with the potential to reach heights of 10 to 12 feet in moist conditions.How to get rid of poison hemlock for good - Farm and Dairy (2)

Leaves are dark glossy green, fern-like, triangular, and 3-4 times pinnately compound (as shown in the picture). Probably the most distinguishing feature is the plant’s smooth hairless purple-spotted stem, which is hollow between the nodes.

(Video) How to safely remove a small patch of poisonous hemlock

Once the plants start to flower, they will be small, white, and found in umbrella-shaped clusters.

Looks like wild carrot

Sometimes poison hemlock gets confused with wild carrot (a.k.a.: lace flower, Queen Anne’s lace). However, wild carrot has hairs along its slender stem and leaf bases while poison hemlock’s stem is smooth and purple-spotted.

Peak bloom for poison hemlock is in late May and early June, whereas wild carrot is just beginning to produce flowers. Wild carrot will only reach heights of 3 feet or less.

Also, poison hemlock is more branch-like than wild carrot.

Take action

Once poison hemlock is successfully recognized and confirmed, the next step is to take action to control it.

Besides using my method of mechanically controlling the plant (hand-pulling, whacking, cutting, mowing, etc.) chemical control is also a viable option. Since poison hemlock is a biennial, it is best to control first-year plants by applying herbicides in the fall, and for second-year plants, applying herbicides in the spring before the plant gets too large.

According to the Ohio State University Weed Control Guide, Crossbow and Remedy Ultra has the best rating for controlling poison hemlock (rating of 9) followed by glyphosate (Roundup), dicamba, and Cimarron Max, which all have a rating of 8.

(Video) What you need to know about poison hemlock

It is important to note that these herbicides are either broadleaf killers (including legumes) or nonselective (kills both grasses and legumes). For light infestations, spot treatment may be the preferred method.

Remember, poison hemlock is one of Ohio’s 21 noxious weeds and should be controlled.

For more information on poison hemlock or help with identifying it, contact your local Extension office.


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How to get rid of poison hemlock for good - Farm and Dairy? ›

chemical control is also a viable option. Since poison hemlock is a biennial, it is best to control first-year plants by applying herbicides in the fall, and for second-year plants, applying herbicides in the spring before the plant gets too large.

How do you get rid of hemlock? ›

An herbicide containing a 41% or higher concentration of glyphosate should be used, and it should be mixed to a 2% product spray solution. Glyphosate will kill grass and other vegetation so care should be taken if used around desired vegetation.

Are there any benefits to poison hemlock? ›

Despite serious safety concerns, hemlock leaves, root, and seeds are used to make medicine. It is used for breathing problems including bronchitis, whooping cough, and asthma; and for painful conditions including teething in children, swollen and painful joints, and cramps. Hemlock is also used for anxiety and mania.

How do you treat poison hemlock in cattle? ›

Ideally, growers can control poison hemlock with herbicide products, such as 2, 4-D applied during the plant's vegetative growth stage in the late winter or early spring or with a herbicide treatment in the fall.

Can you compost poison hemlock? ›

Do not attempt to compost poison hemlock as the poisons are persistent. Even the use of weed trimmers needs to be conducted using precautions so that plant material doesn't come into contact with the body. Identification and eradication of this plant wherever livestock and people could come in contact is important.

Will goats eat poison hemlock? ›

Poison hemlock is often found along roadsides, edges of cultivated fields, stream banks and pasture fencerows. Its most defining characteristics are purple spots or blotches on the plant's hairless, ridged stems. If eaten, all parts of the plant can be fatally toxic to cattle, horses, swine, sheep and goats.

Can you burn poison hemlock? ›

Do not burn the plant, as the smoke can contain deadly toxins. In fact, hemlock is so poisonous that some of poison hemlock's alkaloid compounds have the ability to pass into milk when animals feed on sublethal amounts of this plant, which can adversely alter the flavor and safety of milk used for human consumption.

Is hemlock poison traceable? ›

Its deleterious effects on the human system are well known, owing to the fact that it is found in nearly all parts of the United States. It is of general interest because poisoning directly traceable to this plant has caused many deaths among men and animals.

Can chickens eat poison hemlock? ›

Toxic components

Poison hemlock is highly toxic to all animal species, including humans.

Can pigs eat poison hemlock? ›

It is very toxic and sheep, cattle, swine, horses, and other domestic animals are poisoned by eating small amounts of green or dried plant. It is also extremely poisonous to humans. Poison-hemlock is sometimes confused with western water hemlock, a more deadly species, because the names are similar.

Will horses eat hemlock? ›

Hemlock is fatal even in small quantities and causes paralysis followed by death. Other members of the same family which can cause fatal poisoning include water dropwort and cowbane whose sappy stems can prove attractive to equines in dry weather conditions.

What plants Cannot be composted? ›

  • Tea and Coffee Bags. Coffee grounds and tea leaves definitely belong in a compost pile. ...
  • Citrus Peels and Onions. ...
  • Fish and Meat Scraps. ...
  • Glossy or Coated Paper. ...
  • Sticky Labels on Fruits and Vegetables. ...
  • Coal Fire Ash. ...
  • Sawdust From Treated Wood. ...
  • Large Branches.

Can poisonous plants be composted? ›

The quick answer is YES, you can compost all plants in a compost heap, poisonous or not as the chemical compounds that make up the toxins are effectively broken down during the composting process.

Do any animals eat poison hemlock? ›

Goats and sheep can eat as little as 3 ounces of the plant and show clinical signs; however sheep tend to be able to metabolize the toxin better than most species. The toxin also causes birth defects in goats. If an animal does not progress to respiratory distress and death, prognosis is good for recovery.

Is hemlock toxic to sheep? ›

Overview. Hemlock is a biennial weed probably best known for its poisonous properties. As such, it is not welcome in pastures, nor in urban waste areas. However, there are not many livestock losses from hemlock, as most livestock recognise it as being poisonous and leave it alone.

Can poison hemlock hurt horses? ›

While the toxin content declines as the plant dries, it can still be toxic in hay. Death can occur if a horse eats between 0.2 to 0.8 percent of its body weight in poison hemlock. This amount is equal to 2 to 8 pounds of poison hemlock per 1,000-pound horse.

What herbicide kills poison hemlock? ›

► Chemical There are two herbicides that can be used to control Poison hemlock they are both non-selective chemicals and kill nearly all types of plants. Glyphosate is a non-selective active ingredient found in a number of products (like RoundUp Pro® , with 41% glyphosate) that are effective in controlling hemlock.

What happens if you touch a poison hemlock plant? ›

Poison hemlock looks pretty—but touching it could kill you.

As Healthline explains, common symptoms of hemlock poisoning include trembling, dilated pupils, muscle paralysis, loss of speech, and eventually, respiratory failure and death.

How do you harvest poison hemlock? ›

Poison hemlock can be controlled in small areas around the home, but extreme care should be taken when removing it by hand. Wear rubber gloves and use cutters that can be washed in soap and water. Cut the plant into small portions and place in bags to set in the trash.

How do you test for hemlock? ›

Poison-hemlock stems have reddish or purple spots and streaks, are not hairy, and are hollow. Leaves are bright green, fern-like, finely divided, toothed on edges and have a strong musty odor when crushed. Flowers are tiny, white and arranged in small, umbrella-shaped clusters on ends of branched stems.

Who died of hemlock poisoning? ›

The death of Socrates in 399 BCE, as reported by Plato in the Phaedo, is usually attributed to poisoning with common hemlock.

What is the most poisonous plant in the world? ›

The oleander, also known as laurel of flower or trinitaria, is a shrub plant (of Mediterranean origin and therefore, resistant to droughts) with intensely green leaves and whose leaves, flowers, stems, branches and seeds are all highly poisonous, hence it is also known as "the most poisonous plant in the world".


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