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Hemlock advice

To help reduce the potential harm of the hemlock plant please make sure you read the advice set out below so you can keep yourselves and others safe on the allotment.

Hemlock flowers    Hemlock foliage    Hemlock stem


  • Purple/reddish splotches on central stem. These become more pronounced as the plant develops. 
  • The central stem has sets of two opposite branches with triangular featherlike leaves along these. The central stem itself is hairless and hollow. The plant has a long whitish taproot.
  • Unlike similar looking edibles, the hemlock has a distinctive unpleasant musty smell if the plant is damaged. 

Hemlock can look very similar to other plants including carrots, parsnips, chervil and cow parsley. 


Hemlock has a two-year lifecycle (growing from seed to fruition and then dying). However, the seeds can lay dormant and remain viable for 3-5 years.


Hemlock grows on damp ground, such as riverbanks, ditches, waste grounds and road verges. The flower heads (which are umbrella-like) flower in June and July. 

How to safely remove Hemlock

  • Always wear gloves, mask, and protective clothing when handling the plant.
  • Dig out all the plant(s), including the long taproot, (alternatively, glyphosate treatment can be used to eradicate the plant). 
  • Wash your hands, preferably with soap, after bagging up the plant for removal. 
  • Continue to monitor the area for seedling growth. 


Hemlock is highly toxic to livestock and humans and can be fatal. Both the growing and cut dried plant are poisonous.

Those with hemlock poisoning will display symptoms after 30 minutes to three hours depending on the amount ingested. 

When touched the plant can generate a painful rash, or painful burning on the eyes if contact is made here. 

Consuming any part of the plant can lead to poisoning which affects the nervous and respiratory systems and can lead to respiratory failure.

Symptoms include trembling, burning sensation in digestive tract, increased salivation, dilated pupils, muscle pain, weakness, rapid followed by decreased heart rate, loss of speech, convulsions and unconsciousness.

Seek medical attention immediately if you experience any symptoms or think you have come into contact with the plant.

If possible, take a sample of the plant for identification. Do not try and make the patient sick and help them to remain calm. 

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