How to Kill Hogweed


Hogweed, notably the invasive giant hogweed (Heracleum mantegazzianum), is a plant that can pose significant challenges to both human health and biodiversity. Being able to correctly identify hogweed, especially distinguishing between the less harmful common hogweed (Heracleum sphondylium) and its giant counterpart, is crucial for effective management. The familiarisation with the correct identification methods and understanding the differences between the species can help prevent the unintended spread of these plants.

To tackle the threat of hogweed, especially the giant variety, specific safety measures and protective gear are essential due to the plant’s toxic sap. Contact with the sap, followed by exposure to sunlight, can result in severe skin reactions. Therefore, ensuring the safety of those involved in the removal is paramount. Employing effective removal techniques, such as mechanical methods or approved herbicides, must be carried out with care to ensure thorough eradication while minimising environmental impact.

Things to consider:

  • Accurate identification of hogweed species is vital for control and prevention measures.
  • Personal safety is essential due to hogweed’s harmful sap which necessitates protective clothing and equipment.
  • Strategic removal techniques aid in thorough eradication, aligning with legal and environmental guidelines.

Identifying Hogweed Varieties

Before attempting to manage hogweed, it’s crucial to identify the specific type you’re dealing with. Your safety may be at risk, particularly with the more harmful giant hogweed.

Common Hogweed Characteristics

Your common hogweed (Heracleum sphondylium) tends to be a large, native species found across the UK. It features:

  • Leaves: Deeply lobed, up to 50 cm wide, with a hairy underside.
  • Stem: Hollow, ridged, and not as robust, it can grow up to 2 metres tall.
  • Flowers: White and arranged in umbels, these flowers bloom from June to August.

Often mistaken for cow parsley, common hogweed is less imposing but can still cause skin irritation.

Giant Hogweed Features

Giant hogweed (Heracleum mantegazzianum), on the other hand, is an invasive species originating from the Caucasus Mountains. Here’s how you can spot it:

  • Leaves: Gigantic, lobed, up to 5 metres tall with a jagged appearance.
  • Stem: Thick with purple blotches and thick bristles, quite sturdy, and grows well over 3 metres high.
  • Flowers: Packed in large umbels measuring up to 60 cm across, they are white and bloom from mid-spring to mid-summer.

Unlike its native counterpart, contact with giant hogweed can result in severe photodermatitis.

Safety Measures and Protective Gear

When dealing with hogweed, your safety hinges on the use of proper protective gear and following strict handling procedures. Exposure to hogweed sap, coupled with sunlight, can result in severe photosensitivity, leading to painful blistering and potentially lasting skin damage.

Appropriate Clothing

  • Gloves: Ensure you wear gloves that are water-resistant and cover your wrists thoroughly.
  • Protective Clothing: Your clothing should be made of synthetic, water-resistant material capable of preventing any sap from soaking through. This includes:
    • Full-length trousers
    • Long-sleeved tops

Handling Hogweed Safely

  • Face and Eye Protection: Always wear a face mask and safety glasses to protect your eyes and face from sap splashes.
  • In the Event of Exposure:
    • Immediately wash the affected area with plenty of soap and water.
    • Avoid sunlight on the area to prevent the risk of severe photosensitivity, and seek medical advice if necessary.

Effective Removal Techniques

To successfully eradicate hogweed from your property, you’ll need to employ specific, targeted methods. Whether you choose chemical or mechanical means, ensuring you have the right tools and substances is crucial for both immediate removal and preventing future growth.

Chemical Control Methods

For chemical intervention, you’ll typically use a herbicide such as glyphosate or triclopyr. These are effective weed killers that, when applied properly, can penetrate the plant down to its roots, including the taproot, which is critical for the plant’s survival. Ensure you strictly follow the directions on the herbicide label.

  • Glyphosate: Apply a glyphosate-based herbicide to the foliage of hogweed, ensuring thorough coverage to facilitate absorption.
  • Triclopyr: If hogweed is near desirable vegetation, consider using a selective herbicide like triclopyr, which is less harmful to grass.

Note: Always wear protective clothing and equipment when handling weed killers to prevent skin contact and inhalation.

Mechanical Removal Strategies

Mechanical methods require manually removing the hogweed. You can use tools such as a spade or trowel to dig out the plants. It’s vital to remove the entire root to prevent the plant from returning.

  1. Digging: Use a sharp spade to dig around the hogweed plant, making sure to extract the entire taproot.
  2. Mowing: Regular mowing can hinder hogweed’s growth if done consistently before the plant sets seeds.

Caution: Hogweed sap can cause skin irritation, so wear protective gloves and clothing, and wash any tools used to prevent sap transfer.

Disposal and Environmental Considerations

Disposing of giant hogweed requires careful attention to environmental safety and stringent methods to prevent further spread of this invasive species. Your actions directly impact the surrounding ecosystem and wildlife, and as such, need to be thoughtfully executed.

Handling Contaminated Waste

When disposing of giant hogweed, it’s crucial to label the plant material as controlled waste. Utilise protective gear to avoid skin contact and sap exposure. Transport the waste securely to licensed landfill sites that can handle such materials. Do not attempt to compost hogweed as it may lead to the dissemination of seeds or regrowth.

Preventing Re-Growth

After removal, monitor the area for several years, as giant hogweed seeds can remain viable in the soil. Implement a regular inspection and removal routine. If you have to use herbicides, follow legal guidelines carefully to mitigate environmental impact. Continuous management is fundamental to ensure that this invasive plant does not re-establish itself and pose further threats to indigenous flora and fauna.

Legal Obligations and Reporting

As someone dealing with giant hogweed, you need to be aware of the legal obligations regarding the control, disposal, and reporting of this invasive species. Non-compliance with these laws can lead to serious consequences.

Regulations and Compliance

The Wildlife and Countryside Act 1981 stipulates that it is an offence to plant or otherwise cause giant hogweed to grow in the wild. Given the highly invasive nature of this plant, especially around sensitive habitats such as riverbanks and streams, your actions to control its spread could have legal implications. In the UK, it’s crucial to ensure that any management of giant hogweed complies with this act to protect local biodiversity and prevent the further spread of the weed into areas like rivers, ravines, and adjacent roads.

Notifying Local Authorities

If you identify giant hogweed on your property or nearby, especially near critical areas like rivers and streams, it’s essential to inform your local authorities. These authorities are responsible for monitoring and managing invasive species and can provide guidance on how to safely control and dispose of the plant matter. Proper disposal is usually required due to the plant’s potential to spread via landfill sites and other means. By notifying the relevant bodies, you actively participate in safeguarding your local habitat from invasive plants.

Frequently Asked Questions

In managing hogweed, it’s crucial to know the right techniques for removal, identify the type of hogweed you’re dealing with, treat any potential skin burns, understand the costs involved, and explore both natural and medical treatments for exposure.

What are the steps for safely removing giant hogweed?

To safely remove giant hogweed, first, ensure you are wearing protective clothing to prevent the sap from contacting your skin. Begin by cutting the plant at its base, disposing of the parts securely, and regularly monitoring the area for regrowth. For a detailed approach, review How to Get Rid of Common Hogweed.

How can one differentiate between common hogweed and giant hogweed?

Common hogweed typically grows up to 2m tall, with broad, flat-topped flower clusters, whereas giant hogweed can reach towering heights of 5m and has thick, green stems with purple blotches. Understanding these differences is important for appropriate handling and control measures. More identification tips can be found here.

What methods are effective for treating skin burns caused by giant hogweed?

If you come into contact with giant hogweed sap, quickly wash the area with cold water and avoid sunlight, as UV radiation can exacerbate the burn. Seeking medical advice is also imperative. For immediate first aid suggestions, see the advice offered by Garden Dad.

What are the estimated costs associated with the professional removal of giant hogweed?

Professional removal costs can vary widely based on the extent of the infestation and location. It is best to get several quotes from local professionals to ensure you are getting a fair and competitive price for the service.

Are there any natural remedies recommended for the control of hogweed growth?

Natural remedies such as covering the soil with tarps to starve the plants of sunlight or using vinegar as a natural herbicide can be effective. However, these methods may take longer and require consistent effort.

How should one treat hogweed rashes, as advised by the NHS?

For hogweed rashes, the NHS advises covering the affected area from sunlight and seeking medical help if the skin reaction is severe. You must resist the urge to scratch the rash to prevent further irritation and potential infection. For more detailed NHS advice on skin reactions to plants, click here.

About the author 


Hey there, I am founder and editor in chief here at Good Grow. I guess I've always known I was going to be a gardener. I'm on a mission to share my UK based weed control & lawn care tips with you all. If you have any queries please post in the comments below.

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