Property Care Association

08000 546 436

Giant Hogweed plants

JBB Knotweed News

What is Giant Hogweed and when is the best time to treat it?

Giant Hogweed, though not native to the UK, has made itself quite at home since its introduction in the early 19th century, spreading far and wide across the country. You’ll often spot it lining riverbanks, edging roadsides, and surprisingly, even creeping into urban areas like public walkways and backyard gardens.

But don’t be fooled by its seemingly harmless appearance; this plant is a force to be reckoned with. With no natural predators to keep it in check, Giant Hogweed has become a serious invader, posing a threat to native flora and fauna. In fact, it’s considered such a menace that it’s covered by invasive species legislation, making it illegal to let it run rampant beyond your property lines. And if the environmental damage isn’t enough to make you wary, there’s also the health hazard to consider. Its sap is toxic, capable of causing painful blisters, burns, and even long-term sensitivity to sunlight upon contact with the skin.

What does Giant Hogweed look like?

We have broken the plant down into 4 key parts to aid with identification however an experienced surveyor should always be consulted:

1. Stems

Giant Hogweed stems are green with purple spots, covered in bristly white hairs, and are thick, hollow, and rigid.

Giant hogweed stem

2. Leaves

Giant Hogweed leaves are broad spanning up to 1.5m wide when fully grown.  Its leaves are deeply incised, with sharply serrated edges and a rough texture.   

Giant hogweed leaves

3. Flowers

Giant Hogweed flowers form large, umbrella-shaped clusters (known as umbels) composed of numerous small white flowers.  Giant Hogweed typically flowers from late spring to mid-summer with flower heads that span up to 60cm.  These impressive floral structures can tower above, reaching considerable heights.

Giant Hogweed flower

4. Seeds

Giant Hogweed seeds are small, flat and oval shaped.  They are brown colour and encased within ribbed seed pods which split open when mature to disperse the seeds.  Each seed is lightweight, facilitating easy dispersal by wind or water.  An average Giant Hogweed plant produces between 20,000 and 50,000 seeds which can remain viable for up to 5 years in soils.  

Giant Hogweed seeds

When is the best time to treat Giant Hogweed?

Since the dispersal of Giant Hogweed is almost entirely by seeds it is VERY important to prevent the plant from setting seed.  This makes the optimal treatment window between April and June.  There are a number of options to control Giant Hogweed with herbicide application and excavation being the most common.  Due to the hazards associated with exposure to Giant Hogweed it is strongly recommended that a professional contractor deals with it safely.

National coverage with local service

Our invasive weed surveyors have a wealth of experience in safely removing Giant Hogweed and can advise you on cost-efficient solutions for your site.  We have national contracts across Scotland in areas including Glasgow, Edinburgh, Inverness, Aberdeen and Dumfries and can offer a prompt response to all enquiries.

Our process is simple and hassle free.  For more information click here

Book a Japanese Knotweed Survey

We can tell you if you definitely have Japanese

Knotweed on your property and recommend the

best course of action.

We can tell you if you definitely have Japanese Knotweed on your property and recommend the best course of action.