We all love a beautiful garden, but not every plant is as harmless as it looks. Some species, like Giant Hogweed, hide a dangerous secret beneath their appearance.
This towering plant isn’t just a threat to your garden—it’s a hazard to your health and the environment. Here’s what you need to know to stay safe and help stop its spread.
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What is Giant Hogweed
Giant Hogweed is a tall perennial plant that grows up to 5 meters high. Its large umbrella-like flowers, serrated leaves, and thick purple-speckled stems make it easy to recognise. The plant reproduces through seeds, with a single plant producing up to 50,000 seeds. These seeds are spread by wind, water, and even human activity, allowing them to invade riverbanks, parks, and woodlands.
The plant was introduced from Western Asia into Ireland in the 19th Century as a garden novelty. Over the following years, the plant began to spread uncontrollably, becoming one of Ireland and Britain’s most hazardous invasive species. Let’s break down what makes this plant so dangerous.
The Dangers of Giant Hogweed
The sap of this plant contains chemicals that prevent the skin from protecting itself against UV rays. As a result, exposure to the sap can cause severe burns, blisters, and scars in response to sunlight.
Blisters can form within hours, and the burns can flare up again with future sun exposure. In some cases, the effects can escalate to systemic allergic reactions.
Just recently, 8-year-old Zach Rogers from Northern Ireland was left with scars following exposure to Giant Hogweed.
Picture: Pen News
Giant Hogweed isn’t just a public health hazard—it’s also an ecological menace. Its large size shades out native plants, reducing biodiversity and destabilising ecosystems. Riverbanks invaded by this plant are prone to erosion when the plant dies in winter.
How to Control Giant Hogweed
Cutting or handling this plant can expose you to its sap, putting you at risk of serious burns. Manual removal may also cause seeds to spread, worsening the infestation. As a result, you should always leave removal efforts to trained professionals. Some professional methods of removal include:
Herbicide Injection: Trained professionals use specialised tools to inject systemic herbicides like glyphosate into the plant’s stems. This targets the root system while minimising environmental impact.
Mechanical Removal: For small infestations, deep ploughing or cutting flowering heads during mid-bloom can help control seed production. However, these methods should be handled by experts wearing protective gear.
Grazing Animals: Livestock such as cattle or sheep can help control this plant. Generally, these animals can graze the plant without being harmed. But, care must be taken as the plant can sometimes affect their health and the taste of dairy products.
Long-Term Monitoring: The plant’s seeds can remain viable for up to 15 years. As a result, consistent monitoring and follow-up treatments are essential to prevent re-establishment.
Due to its dangers, there have been extensive efforts to remove this plant from Ireland. A few years ago, Limerick county councils began a three-year project to control its spread.
WATCH: RTE Video Segment “Limerick three-year project to control spread of Giant Hogweed”.
Around 24 hours after touching the sap, the skin will become red, with an accumulation of fluid under the affected part.
— RTÉ News (@rtenews) August 8, 2019
Within three days, a strong inflammatory reaction occurs, and skin will become hyper-pigmented (unusual darkening of the skin), which can last months. pic.twitter.com/1j7C8Bf3hy
A Final Warning for Giant Hogweed
Giant Hogweed is not a plant to take lightly. Exposure can cause burns and ongoing sensitivity to sunlight. If you encounter it, or suspect it could be on your property, don’t touch it & contact professionals.
Luckily, Southern Scientific specialises in invasive species control. We can provide you with an Invasive Species Management Plan for Giant Hogweed. We can also help you control other invasive species such as Rhododendron and Japanese Knotweed.
For further information or help tackling an invasive plant in your garden, get in touch with us by:
Phone: 066 97 63588
Email: [email protected]
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