How To Get Rid Of Giant Hogweed

If you’ve spotted a towering, white-flowered plant that looks like giant cow parsley, you need to act carefully. Learning how to get rid of giant hogweed is essential because this invasive plant is not just a garden nuisance—it’s a serious health hazard. Its sap can cause severe burns and blisters when exposed to sunlight. This guide will walk you through safe, effective removal methods to protect your property and your family.

Complete eradication of giant hogweed requires a persistent, multi-year approach. The plant’s seeds can remain viable in the soil for over 7 years, so a single season of effort won’t be enough. Your strategy will depend on the size of the infestation, your location, and your resources. Always, always prioritize personal protective equipment (PPE) before any contact.

Why Giant Hogweed is So Dangerous

The primary risk comes from the plant’s clear, watery sap. It contains furanocoumarins, which cause phytophotodermatitis. This means if the sap gets on your skin and that skin is then exposed to ultraviolet light (sunlight), it can result in painful, blistering burns. These burns can scar and cause skin to remain sensitive to light for years. The reaction can occure within 15 minutes of exposure.

Severe Skin Burns: Blisters can be as bad as second- or third-degree burns.
Long-Term Sensitivity: Affected skin may remain sensitive to sunlight for many years.
Eye Damage: If sap gets in the eyes, it can cause temporary or even permanent blindness.

Essential Safety Gear You Must Wear

Never attempt to handle giant hogweed without full protection. Assume every part of the plant is coated in sap.

Waterproof disposable coveralls (tyvek suit).
Waterproof gloves (nitrile or rubber, not cloth).
Goggles or a full-face shield.
Waterproof boots that can be washed afterwards.

What to Do If You Get Sap on Your Skin

Act immediately. Wash the affected area thoroughly with soap and cool water. Get out of sunlight and keep the area covered with loose clothing or a bandage for at least 48 hours. If a reaction begins or if sap gets in your eyes, seek medical attention right away.

Method 1: Digging Out Small Plants (Manual Removal)

This is only recommended for very small infestations, like a few first-year seedlings. Mature plants have deep taproots and are too risky to dig.

Don full PPE on a cloudy, overcast day, preferably after rain when the soil is soft.
Using a sharp spade, dig widely around the plant to locate the entire root system.
The goal is to remove the entire crown (where the stem meets the root) and as much of the taproot as possible, at least 8-12 inches below ground.
Carefully place the entire plant into heavy-duty rubbish bags without crushing it.
Do not compost or leave any part of the plant on your property.

Method 2: Cutting the Flower Heads (To Prevent Seeding)

If you cannot fully remove large plants immediately, stopping seed production is your top priority. One plant can produce up to 50,000 seeds.

Wear full PPE. Use sharp secateurs or loppers.
Cut off the flower/seed head as soon as it appears, placing it directly into a bag.
Dispose of the seed heads securely. This must be repeated every year until the plant’s energy reserves in the root are depleted.

The Importance of Timing Your Attack

The best time to cut is late April to early May, before the plant flowers. Cutting after flowering is less effective but still crucial to stop seeds. A second cut in late summer can weaken the root further. Remember, you’ll need to monitor the site for regrowth and new seedlings for at least 7 years.

Method 3: Using Herbicides (For Large Infestations)

Chemical control is often the most effective for large stands. Always use a herbicide approved for use on giant hogweed in your country and follow the label instructions precisely.

Glyphosate-Based Herbicides: These are systemic and kill the root. Apply in late spring when plants are actively growing but before they flower. A follow-up application in late summer may be needed for regrowth.
Professional Help: For very large or dangerous infestations, hiring a licensed invasive species control company is highly recommended. They have the experience and equipment.

When applying herbicide, avoid spraying on windy days to prevent drift onto desirable plants. The plants will die slowly over several weeks. Do not cut them down until they are completely dead and dry, as the live sap remains a hazard.

Disposal: The Critical Final Step

Improper disposal can spread the problem. Never use a compost pile or a municipal green waste bin.

Place all plant parts (roots, stems, flowers, seeds) into heavy-duty black plastic bags.
Clearly label the bags as “Giant Hogweed – Hazardous Plant Material.”
Contact your local waste authority for instructions. They often require disposal in a licensed landfill site.
Thoroughly clean all tools, boots, and PPE with soapy water. Sap can remain active on surfaces.

Restoring the Area After Removal

Once the plants are gone, you need to prevent new ones from taking over. The soil bank will likely have thousands of seeds.

Cover the area with a thick, opaque tarp or landscape fabric for multiple growing seasons to smother any seedlings.
Alternatively, plant a dense, competitive ground cover like native grasses or shrubs.
Inspect the site every spring and fall for new seedlings, which are much easier to remove than mature plants.

FAQs About Giant Hogweed Removal

What does giant hogweed look like?

It grows 10-15 feet tall with thick, purple-blotched stems. Leaves are huge, deeply incised, and up to 5 feet wide. The flower head is a large, flat-topped umbrella (umbel) of white flowers, up to 2.5 feet across.

Can I burn giant hogweed?

Burning is not advised. The smoke can carry toxic sap particles, which are harmful to inhale and can irritate skin and eyes. It also doesn’t destroy the seeds in the soil.

Should I report giant hogweed?

Yes, in many regions you should. Contact your local environmental agency, department of conservation, or county extension office. They can provide specific advice and may track infestations.

How long does it take to fully eradicate it?

Due to the long-lived seed bank, you must commit to a management plan for a minimum of 5 to 7 years. Persistence is key, as new seedlings will continue to emerge.

What’s the difference from cow parsley or Queen Anne’s lace?

Giant hogweed is massively larger in all parts. Common cow parsley rarely grows over 3 feet tall, has finer leaves, and its stem is green and slightly grooved, not thick and purple-blotched. Always err on the side of caution and assume it’s hogweed if you’re unsure.

Removing giant hogweed is a serious task, but with the right knowledge and precautions, you can reclaim your land. Start by suiting up safely, choose the right method for your situation, and stay vigilant for years afterwards. By stopping the seeds and persistently attacking the roots, you will eventually win the battle against this invasive giant.