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Property Surveying Blog
July 6, 2020

Giant Hogweed

Written by Berry Lodge Surveyors

Giant Hogweed

Unbeknown to many homeowners and members of the public, this plant is invasive and dangerous with severe effects on health. 

What is Giant Hogweed?

Giant hogweed, formally known as Heracleum mantegazzianum is a large plant originating from Eastern Europe.

Back in the 19th Century, it was introduced to the United Kingdom as an ornamental garden plant. As with Japanese Knotweed, the introduction of this plant was ill-considered.

These days, this plant often goes undiagnosed and left to grow at will throughout much of the UK at places however will commonly find its place at the waste ground, riverbanks or beside railway lines as these placed tend to be poorly maintained and infrequently at best.

Giant Hogweed is a monocarpic perennial herbaceous flowering plant, surprisingly it actually belongs to the carrot family, however, don’t expect any tasty treats from this plant!

Giant Hogweed can often be mistaken with its relative cow parsley as the two share the same type of flowers. However, unlike cow parsley, giant hogweed can reach a height of 5 metres and produce as many as 50,000 seeds which means it can spread rapidly.

Why is Giant Hogweed So Bad?

Giant hogweed is an invasive non-native species that are harmful to both the environment and incredibly human health.

Giant hogweed is phototoxic, meaning that it contains a toxic component called furocoumarins, of which in combination with bright sunlight can cause painful sores and burns on exposed skin.

This toxic component is found in the giant hogweed’s sap, leaves, seeds, flowers and roots. Even a light brush of it against the skin can cause increased sensitivity to light and irritation. In some cases, severe blistering can happen. Not only does it take these blisters a long time to heal, but they can become very painful and possibly develop into Lyme Disease that causes the skin to be hypersensitive to ultraviolet light.

As if this wasn’t enough, touching giant hogweed can even cause blindness if sap gets into a person’s eyes.

What Happens if You Touch Giant Hogweed?

If you are unlucky enough to accidentally touch giant hogweed, you will need to take prompt action. To start with, you must wash it off immediately with soap and cold water, cover up the affected area, and make sure you stay out of the sun for a minimum of 48 hours.

If are unlucky enough for a toxic reaction to begin, don’t wait, you should seek medical attention as a matter of urgency.

How Can you Control Giant Hogweed?

One conventional and widely used technique for controlling giant hogweed is chemical treatment. This means spraying or injecting the solution into or onto the stems.

The technique is effective and cost-efficient, however, needs to be done by a specialist so be sure to avoid a green-fingered DIY approach!

Another technique is regularly cutting the hogweed to ground level, this will have to be done at least 6 times annually, while you can do this yourself with protective clothing, again we’d advise leaving this for a specialist to do as the risks of injury to an inexperienced person are high.

If you think you’re unlucky enough to have this plant in your garden, we’d advise that you contact an experienced gardener at the first instance. They should be able to visit and advise you of exactly what needs doing to remove it.