Dangerous & Notifiable Weeds in Scotland: What to Do If You've Found One

If you've found a plant that looks like giant hogweed, Japanese knotweed, ragwort or rhododendron, the questions are narrow: will it hurt me or my animals, am I breaking the law by leaving it, and what happens if I don't act. The answer is different for each. Giant hogweed can burn skin, knotweed is a legal and financial headache with no health risk, ragwort can kill horses but is also a food source for pollinators, and rhododendron does serious ecological damage across the Highlands and west coast. Work out which one you're looking at first.

Giant hogweed (Heracleum mantegazzianum)

Photo: Stefan.lefnaer, CC BY-SA 4.0

Why it's dangerous

Giant hogweed's sap contains furanocoumarin compounds that make skin extremely sensitive to sunlight. Contact with the sap followed by sunlight causes phytophotodermatitis, a chemical burn that can produce severe blistering, long-lasting pigmentation and scarring. The reaction is often painless at first, with blisters appearing 24 to 48 hours later, so no pain straight away doesn't mean no injury. The skin can stay sensitive to sunlight for months, and sap in the eyes can cause temporary or permanent blindness. Cut or bruised plant material stays hazardous for hours, so strimming or mowing through it is a real risk, not just brushing against the standing plant.

What to do if sap gets on your skin

1. Wash the area with soap and water immediately.
2. Keep it out of sunlight for at least 48 hours, including on overcast days, since UV still reaches skin through cloud and a grey day gives no protection.
3. Seek medical advice, and see a doctor if you feel unwell or the skin reddens or blisters.
4. Protect the area from the sun for the following months with clothing or sunscreen, since it can stay light-sensitive.

Identification, and where people get it wrong

Size alone rules out most lookalikes. Check it against the plants people most often confuse it with:

The thick, bristly, purple-blotched stem is the most reliable check. None of the three lookalikes have it.

Giant hogweed favours riverbanks, waste ground and roadside verges. A single plant can produce up to 50,000 seeds, which spread along watercourses and in contaminated soil, footwear and vehicles. Verges are cut by council and contractor strimmers, so crews working near a known stand are at real risk.

The law

Giant hogweed is listed in Schedule 9 to the Wildlife and Countryside Act 1981, but Schedule 9 was repealed for Scotland from 2 July 2012 by the Wildlife and Natural Environment (Scotland) Act 2011. Scotland now runs on its own version of section 14, which makes it an offence to plant, or cause to grow in the wild, a plant "at a place outwith its native range". That is a broader test than the named species list used in England and Wales. Giant hogweed is not native to Scotland, so causing it to grow in the wild is still an offence. Having it on your own land is not itself an offence, but you can be liable if you cause it to spread into the wild. Section 14's wording is set out in full in the Himalayan balsam identification and removal law article.

If you're treating hogweed with herbicide near a burn or river, which is where it tends to grow, SEPA's general binding rule GBR 23g lets you apply herbicide to an invasive non-native plant within 1 metre of the top of the bank without contacting SEPA first, provided the product is approved for use near water. Spraying further from the bank, or any plant that isn't an invasive non-native species, needs SEPA contacted in advance. Check SEPA's current guidance on the full conditions before spraying.

Cut hogweed material is classed as controlled waste, as knotweed is below, so it can't go in compost, the council garden bin or general household waste. If the plant has gone to seed, cover the seed heads with a bag before you start cutting, to collect the seeds and limit their spread, and wear gloves and cover as much skin as possible. For anything beyond a plant or two, a specialist removal company is the realistic option: they carry the right protective equipment and are usually registered waste carriers already.

Japanese knotweed (Reynoutria japonica / Fallopia japonica)

Photo: W.carter, CC0 1.0

Knotweed is not in the same danger category as hogweed: there's no first-aid concern. What it costs you is money and legal exposure.

Identification

Japanese knotweed has spade-shaped leaves with flattish bases, usually about 14cm long, arranged in a zigzag pattern along the stem, which is one of the most reliable identifying features. The stems are hollow with reddish-purple speckling and conspicuous nodes, usually about 2m tall. Clusters of small creamy-white flowers appear in late summer and early autumn. Below ground, the rhizomes (thick, woody, root-like stems the plant spreads and regrows from) are dark brown outside with an orange layer beneath, and it is not unusual for them to extend down 1m or more. They form a crownThe base of a perennial plant where roots and shoots meet, often sold and planted as a ready-made dormant plant rather than grown from seed. Full definition → that spreads outward into dense thickets.

What it's commonly confused with

• Russian vine (Fallopia baldschuanica): a close relative with a similarly fast growth rate, but a climbing, twining vine that wraps around structures rather than growing as an upright cane, with smaller leaves that aren't flat-shovel-shaped. See the Russian vine article for the fuller comparison.
• Bindweed: a climber with heart-shaped leaves (knotweed's have a flat base) and large pink-and-white trumpet flowers, against knotweed's small creamy-white sprays. Bindweed has no woody stem.
• Dogwood (Cornus): can look similar in winter with its red stems, but its leaves grow in opposite pairs, while knotweed's alternate up the stem.

Legal status

Japanese knotweed is listed in Schedule 9, and it is an offence to plant it or cause it to grow in the wild. As with giant hogweed, Schedule 9 was repealed in Scotland from 2 July 2012 and Scotland uses the broader "outwith its native range" test under its own section 14. The penalties for these offences are set out in the Gunnera tinctoria article.

Knotweed, and soil containing it, is regarded as controlled waste under the Environmental Protection Act 1990. Section 34 places a duty of care on anyone who produces, carries or disposes of it, and Scotland has its own amended version of that duty. In practice you can't put knotweed material in a garden waste bin or bonfire it and walk away: off-site removal has to go through a registered waste carrier to a licensed facility, with the movement recorded on a waste transfer note (the paperwork the carrier gives you as proof it went somewhere licensed). Sections as small as 1cm can grow into new plants, which is why herbicide treatment, which usually takes at least three growing seasons, or professional excavation are the realistic options rather than DIY digging-out. The SEPA watercourse rule described for hogweed applies here too.

Costs vary hugely with the treatment chosen and how established the stand is. A multi-year herbicide programme usually costs less than full excavation and removal of contaminated soil, and site access, depth and area all move the price. Get more than one quote from a specialist before committing to either route.

Buying, selling and mortgages

In England, sellers complete a property information form (TA6) that asks directly about knotweed. Scotland's system works differently: property is sold through Home Reports and solicitors' missives, and the Scottish Standard Clauses typically have the seller declare that the property isn't affected by rot, damp, woodworm or "other infestation" beyond what the Home Report discloses.

That clause has been tested in a Scottish court. Buyers John Busby and Marie Donnelly found a substantial stand of Japanese knotweed on a property they'd bought in Auchendinny. The sellers knew about the knotweed and had tried to treat it without total success. At Edinburgh Sheriff Court, Sheriff Christopher Dickson rejected the sellers' argument that "infestation" covers only insects or animals, and the buyers' claim was allowed to proceed. That was a preliminary ruling rather than a final judgment, but it signals that knotweed can count as an "infestation" under that clause, a reading supported by a February 2022 RICS information paper.

If you're buying or selling a property with knotweed on or near it, ask your solicitor directly what they'll need disclosed and how lenders are likely to treat it, rather than assuming the English process carries over.

Ragwort (Senecio jacobaea)

Photo: Rosser1954, CC BY-SA 4.0

Identification

Ragwort is usually biennialA plant that completes its life cycle over two years: growth in year one, then flowering, seeding and dying in year two. Full definition →. In its first year it forms a low, overwinteringKeeping a plant alive and intact through the cold months, whether left outdoors, moved under cover, or stored dormant. Full definition → rosette of dark green, deeply lobed leaves, which is when it's most easily overlooked. In its second year a stem rises, often much shorter than its maximum of about 1.5m, topped with a dense head of yellow daisy-like flowers from July to October. It can be confused with tansy, which has similar flat-topped yellow clusters but finely feathery, fern-like leaves rather than ragwort's coarser, jagged lobes. The leaf shape is the more reliable check.

Why it matters

Ragwort is poisonous to horses and livestock. Eating the green or dried plant can cause serious liver damage and can be fatal. If you're pulling it, wear sturdy, waterproof gardening gloves, cover arms and legs, and wear a facemask to avoid breathing in pollen or plant particles. Wash any skin that contacts the plant in warm soapy water straight away.

Grazing animals tend to avoid the fresh plant, but the toxins stay in it once it's cut and dried, so ragwort mixed into hay or silage is the bigger risk. Livestock keepers who make silage or haylage should check fields for ragwort before they are cut.

The legal framework, and how Scotland differs

Ragwort is one of five injurious weeds named in the Weeds Act 1959, alongside spear thistle, creeping or field thistle, curled dock and broad-leaved dock, and it is the only one of the five that is harmful to horses and other animals. The Act applies in Scotland, England and Wales. A notice can be served on the occupier of land requiring them to stop injurious weeds spreading, and failing to comply without reasonable excuse is an offence.

The Ragwort Control Act 2003 and its Code of Practice cover England and Wales only. Scotland has its own Scottish Government guidance, "How to prevent the spread of ragwort", issued under section 38 of the Animal Health and Welfare (Scotland) Act 2006. It takes a risk-based approach rather than a fixed-distance rule: where ragwort poses a high risk to grazing animals or feed and forage production, it must be controlled, while amenity grassland and woodland generally represent a low risk. On grazing land, control is the responsibility of the occupier (owner or tenant). For motorways and trunk roads it is Transport Scotland, for other public roads the local authority, and for railways Network Rail.

If ragwort on neighbouring land threatens your grazing animals, raise it first with the landowner or occupier. If they don't act, the Scottish Government's Rural Payments and Inspections Directorate can be contacted, and the guidance sets out the steps a complainant should take. Growing ragwort is not itself a criminal offence: the obligation bites if a formal notice is served and then ignored.

The wildlife-value caveat

Ragwort contributes to the biodiversity of the countryside where there is no risk to animal welfare. It is the main food plant for the caterpillars of the cinnabar moth, and its flowers attract a range of pollinators. So the guidance is about controlling it where it is a real risk to grazing animals or forage, not removing it wherever it grows. Near grazing land, pulling plants before they flower and set seed avoids the worst of the conflict, and ragwort well away from grazing land or forage production doesn't need treating as a problem.

Rhododendron ponticum

Photo: Cultureel Gelderland, CC0 1.0

Identifying it, and not confusing it with a garden rhododendron

Most rhododendrons in Scottish gardens are hybrids, bred by crossing R. ponticum with North American and Asian species, and they are not the problem. R. ponticum has tough, leathery, dark green, oval leaves and purple, funnel-shaped flowers in trussesThe flowering, then fruiting, stem cluster on a tomato plant; each truss ripens its fruit together. Full definition → of 10 to 20 in spring, and grows to 2.5 to 4m. Garden hybrids come in a much wider range of flower colours (white, pink, red, spotted), so a thicket flowering anything other than purple to mauve is more likely a hybrid or garden escapee, though it can still spread if left unmanaged near woodland.

Why it's a problem

Rhododendron isn't a skin hazard, but the plant is harmful if eaten, so keep pets and livestock away from it. The real problem is what it does to a landscape. It forms dense thickets that shade out native plants, and its roots and leaf litter are toxic to many other plants. Left unmanaged it can dominate a woodland understorey and exclude almost everything else.

It also harbours Phytophthora ramorum, the pathogen behind "sudden oak death", which in Scotland is mainly a serious threat to larch. P. ramorum was first found in Scotland in plant nurseries on rhododendron in 2002, and on larch in the west in 2010. Statutory Plant Health Notices from Scottish Forestry require infected larch to be felled together with the larch within a 250m buffer everywhere outside the south-west management zone, where infection is so widespread that statutory felling is no longer pursued. Rhododendron near larch woodland is what turns an infestation into a forestry problem rather than just an aesthetic one.

The problem is concentrated in the west, where the climate is warmest and wettest. Forestry and Land Scotland describes rhododendron as particularly widespread on the Kintyre peninsula around Carradale.

Legal status

Rhododendron ponticum is listed in Schedule 9 and, as with hogweed and knotweed, Schedule 9 was repealed in Scotland from 2 July 2012, replaced by the "outwith its native range" offence under Scotland's section 14. It isn't banned from sale, but it is an offence to plant it or cause it to grow in the wild in Great Britain.

Why it's so hard to kill

Rhododendron regrows vigorously from cut stumps, from branches that root where they touch the ground and from seed, so cutting it back alone achieves very little. Effective control generally means one of two approaches: applying glyphosate directly to a freshly cut stump (ideally within a couple of days of cutting) so it's drawn into the root system, or stem injection, where holes are drilled into the main stem and dosed with herbicide, which avoids spraying foliage and suits sites near water. Smaller plants can sometimes be dug out by hand or with a mattock, but incomplete root removal risks regrowth. At landscape scale, control means repeat visits over many years and coordination with neighbouring landowners, since seed blows back in from untreated stands. Check the current approval and label for any herbicide before using it.

Legal status at a glance

Despite the "notifiable" label some sites use, there is no general legal duty to report any of these four. The law works through offences (planting or causing growth in the wild) and, for ragwort, notices served on occupiers.

Common questions

Sources