Giant Hogweed

What is Giant Hogweed?

Giant Hogweed – a poisonous plant which used to be quite rare – but has now spread throughout the UK and is now found in pandemic amounts along the river banks and river side footpaths and canal towpaths in the Greater Manchester area

Giant Hogweed

Giant Hogweed – Don’t Touch It – Report It


Sap of the Giant Hogweed is an irritant which can cause severe blistering which can take up to 6 months to heal

Can be re-activated by sunlight for up to 6 years after initial exposure.

  • 4 year life cycle
  • Grows to about 3-4m high
  • Large white umbrella shaped flower head
  • Poisonous Sap from stem and from hairs on stem
  • Plants take 3 – 4 years growing before they bloom and seed
  • Each plant can produce between 10k – 80k seeds.
  • Seeds can lie dormant for up to 15 years

People can be exposed to this sap by simply brushing against the stem of the plant. By cutting the plant down without being aware of the dangers, by stroking their dog which has brushed against the plant – and also it is a very attractive/distinctive plant which can attract children – who have been known in the past to use the stems as pea shooters (this can cause blindness).


Giant Hogweed - Don't touch it - the sap can burn your skin!

Giant Hogweed – Don’t touch it – the sap can burn your skin!

Where Is It Found In Our Area ?

River Irwell, Middlebrook, Eagley Brook, River Croal, Kirklees Brook, River Irk, Moston Brook,River Tame, River Goyt, Black Brook, River Mersey, River Bollin and Manchester Ship Canal and Salford Quays.

It has also been spotted growing on the hard shoulder of the M60 between junctions 16 and 17 on both sides of the carriageway, the A57 between Eccles and Irlam, and even Junc 18 of the M6 !!

Why Has The Spread Of This Plant Increased So Rapidly In The North West?

Despite all local authorities in our area, and the Environment Agency having some form of spraying program, spraying is generally ineffective as a means of eradicating Giant Hogweed, unless the top most plant in each tributary of the catchment is killed. (its a futile exercise spraying plants only for the river banks to be re-seeded each autumn from plants upstream)

There is no multi council / agency strategy for dealing with the plant so each year the numbers of plants and the scale of the problem gets worse. A disjointed spraying program and a lack of communication between local agencies is an ineffective and poor use of resources.

There is a total absence of any sort of awareness program, or implementation of laws that are designed to protect the public from the dangers that this plant presents.

How Can Giant Hogweed Be Controlled ?

It can be killed simply and effectively by spraying the plant with a commonly used herbicide called “Round Up” also known as Glyphosate.

What Can The Public Do To Help Eradicate Giant Hogweed And Make Our River Banks Safe ?

If you see Giant Hogweed growing – report it via this website

We view the results from this website, and it helps us plan an eradication program

It only takes one plant to go to seed and then there are potentially 10,000 to 80,000 more seeds / potential plants to be dealt with in the future!!

Hogweed Burn And Blister

 What Can Our Local Authorities Do To Make Our River Banks Safe ?

Fund the Mersey Basin Rivers Trust to create an effective program of eradication.

Implement the Law – to prevent private land owners from allowing Giant Hogweed to grow on their land.

Its simple – but needs coordination, determination and adequate funding