Giant Hogweed

Japanese Knotweed Plus Ltd in the news

Please see this article in the Metro for more information.

Introduction to Giant Hogweed.

Giant hogweed (Heracleum mantegazzianum), is part of the carrot family. It was widely spread throughout the UK, Europe, and the world. Attitudes towards the plant have become highly negative, supported by numerous stories and myths in the press and on the web. Hogweed can be very poisonous for humans & animals. A lot of varieties of well-established native species in the UK are poisonous too.

It was introduced to the UK in 1893 by the Victorians as an ornamental plant from the Caucasus Region and Central Asia. Now, it is one of the most successful and dangerous plants growing in the UK. The plant is found along river banks, footpaths, in parks and other public areas. The widespread of giant hogweed was facilitated by ignorance in following strict recommendations on how to deal with the plant, this has contributed to the problem.

The hogweed family (Heracleum) accounts for around 70 varieties around the world, with an attractive appearance, giant hogweed plants can reach up to 15 feet high. The hogweeds flowers are an upturned umbrella in shape and can reach up to 3 feet in diameter, producing lots of pollen and nectar for honeybees and holding up to 80000 seeds. The leaves can grow to 6 feet across giving validation to the Latin name Heracleum.

After spreading throughout Russia, the leaves of the plant were added to soup or borsch in early spring. The shoots can be marinated and the leaves salted for further use. The leaves are dried after soaking in water or alternatively boiled to remove etheric oil. The roots, rich in sugar can be used to produce sugar. This plant is mainly found the in Caucasus region.

There is no legal obligation in the UK to remove or control the plant when it is growing in your garden. The plant is listed in the Schedule 9 Part 1 of the Wildlife and Countryside Act 1981 (as amended) beware, as spreading it in the wild is an offence and may be a subject to a penalty of up to £5000 or imprisonment. The sap contains a photoactive toxic glucoside called furocoumarin and can be found in the leaves, stems & seeds. Contact with the sap on human skin followed by exposure to the UV light of the sun can cause serious burning and can even be lethal to children if the exposed area is sufficiently large enough. Interestingly, furocoumarins from other natural products such as celery, lime, coriander, carrots and parsley can make the skin sensitive to the UV fraction of sunlight.

Need help with managing Giant Hogweed on your land? Call for FREE for advice today;

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Giant Hogweed in the News.

In the Late Sixties

After starting to spread noticeably in the 1960’s, the issues after contact with the plant were recorded. The British Medical Journal reported on erythematous patches on arms, neck and legs of a seven-year-old boy (13 July 1968, Correspondence from Janet H. Smellie from Liverpool).

In the Present Day

BBC News (10/07/2015) reports of two boys in Bolton were hospitalised after touching giant hogweed. The NHS recommended anyone who comes into contact with the plant should wash the exposed areas with water and soap then cover the area, preventing the skin from coming into contact with direct sunlight.

***Warning: photographs*** The Sunday Express (24/07/2015) tells a story about the first court case after a seven-year-old boy was severely affected by giant hogweed in a holiday park that was extensively infested with the plants.

Daily Mail
***Warning: photographs*** In the Daily Mail, leading experts explain how dangerous giant hogweed is, it warns that the plants now fall under the ASBO legislation.

Removal Options for Giant Hogweed.

Giant hogweed is now often referred to as the most dangerous plant in the UK. Therefore, strict safety measures must be implemented when dealing with the plant. We strongly recommend contacting dedicated contractors for the removal of giant hogweed. Similar to Japanese knotweed, giant hogweed can be eradicated employing physical removal or by applying chemicals. As a company that specialises in the eradication of the range of invasive weeds, Japanese Knotweed Plus Ltd will eradicate giant hogweed by physically removing or by applying chemicals, this is dependent on your particular case, circumstances and the time of the season.

Cutting the upturned umbrella-shaped flower before they go to seed

This is the most effective way to eradicate hogweed in small areas. However, this is also one of the most dangerous methods due to the possibility of splashing sap onto the unprotected skin. If the correct time for trimming buds or flowers has been missed, special attention should be given to prevent the growth of new side-shoot umbrellas from the main rosette. Otherwise, once the plant has produced new umbrellas with flowers in their ovaries there will be a new generation of seeds, enough to restore the thickets of the plant.


Incineration is an effective way to destroy the maturing seeds and should be undertaken before the ripening process in the central largest umbrella is completed. The method requires care and accuracy, as, during burning, the umbrellas become flammable due to the oils in the seeds. The use of this method may not be permitted in residential areas.

Treatment with herbicide

Be aware, the use of different types of approved herbicides is now only allowed by accredited specialists.

Since 26 November 2015, operation under the Grandfathers Rights exemption is no longer allowed.

Operators applying professional herbicide must possess UK recognised certification. This certificate is also required to purchase these herbicide products.

Our professional operatives are obliged to contact the Environment Agency if treatments are to be carried out near to waterways.

Japanese Knotweed Plus Ltd is accredited by City & Guilds to apply pesticides in land and aquatic areas using both spraying and injection techniques.

Have a problem with giant hogweed? Call us on 0161 883 0666


This is an effective way to destroy hogweed but only before flowering. This must be repeated no later than 3-4 weeks after the first mowing. This technique is necessary to destroy all the generative shoots bearing inflorescences and the flowers accordingly. It is important to prevent hogweed from blooming and from forming new seeds. If hogweed was mowed only once in the middle of flowering it will only contribute to further proliferation of plants.

Precautions when Destroying Giant Hogweed.

Don’t Mow hogweed between the end of flowering and early seeds set. This will not have the desired effect unless you are planning on destroying the crop immediately after mowing it. Any hogweed that has been cut down must be removed immediately in a heap and burned. This is one of the most efficient ways to destroy the seeds.

Don’t Leave the cut-down hogweed in situ. Even after it has been cut down, the main umbrella stem of the hogweed stores large supplies of nutrients enough to provide the seeds to germinate, ripen and give life to new plants.

Don’t Mow hogweed which is shedding seeds. This will just lead to a greater dispersion of hogweed. If the umbrellas with ripe seeds are cut, especially in windy conditions it will help spread the seeds to new areas.

Don’t Deal with hogweed without protective clothing. Waterproof clothing is strongly recommended, as a plant sap may penetrate through ordinary clothes and touch the skin. If the sap comes into contact with human skin and is not washed off within 24 hours it will result in burns.

If you are accidentally exposed to the sap of Giant Hogweed, YOU MUST contact your doctor or nearest A & E department immediately.

Rinse the affected skin as soon as possible with cold running water and gently cover the area from the UV light of the sun (UV light will not pass through ordinary window glass).

Use liquids containing alcohol for rinsing the affected areas (DO NOT RUB).

Don’t use any fixed bandage. You MUST carry out all the measures traditionally prescribed for skin burns.

Japanese Knotweed Plus Ltd will help you get rid of giant hogweed through our safe and hassle-free treatment procedure

Call us on 0161 883 0666