Japanese knotweed specialists

What a knotweed specialist does

The contractor starts with a survey to confirm the plant and map how far the rhizomes, the underground stems, have spread. They then write a management plan and carry out the treatment.

• Herbicide is the cheapest and slowest route, over three to five years. It usually means one or two applications in year one, then yearly until regrowth stops, then two years of monitoring and a completion certificate.
• Excavation and disposal is the dearest route and takes one to four weeks.
• Root barriers can contain it where digging is not practical.

Glyphosate control needs at least three growing seasons. Clear access for the contractor, and do not strim or dig the plant yourself.

What to expect on site

At the survey, the contractor identifies the plant, walks the boundary and looks for rhizome spread, including on neighbouring land within 3 m, where RICS asks surveyors to report it. You should then get a written plan, a price and a timetable.

Herbicide visits are short, because spraying a stand takes a few hours, but they recur every year until regrowth stops. Excavation is a short, noisy project in which soil is dug out, loaded and taken to a permitted site with waste transfer notes. Keep every note: buyers' solicitors often ask for them.

Is it really knotweed?

Bindweed, bamboo, Himalayan balsam, giant hogweed and several garden plants are often mistaken for it. Check our guide to identifying Japanese knotweed first. A photo sent to a PCA or INNSA surveyor is the safest way to be sure. Surveys are easiest from April to October.

Is it illegal to have knotweed?

No. Having Japanese knotweed on your land is not an offence. But under section 14 of the Wildlife and Countryside Act 1981 it is an offence to plant it or cause it to grow in the wild, so you must stop it spreading.

Councils and police can issue a community protection notice to a landowner if knotweed has a persistent, detrimental effect on the community. Failing to comply with the notice is an offence, with a fixed penalty of up to £100.

Waste: a legal duty of care

Cut knotweed and soil that contains rhizomes are controlled waste under the Environmental Protection Act 1990. Use a registered waste carrier, a permitted site and waste transfer notes. Never put it in a green waste bin.

Burning on site needs an Environment Agency D7 exemption. The legal requirement for the contractor is a registered waste carrier for soil taken off site.

Selling a home: the TA6 form and RICS guidance

The TA6 property information form (5th edition, 2024) asks: "Is the property affected by Japanese knotweed?" You can answer Yes, No or Not known. Answer No only if you are certain there is no rhizome in the ground of the property or within 3 m of its boundary. A wrong answer can lead to a misrepresentation claim.

The RICS standard on Japanese knotweed and residential property, effective from 23 March 2022, sets four Management Categories used by valuers and surveyors:

• A, Action: visible material damage to a structure.
• B, Action: likely to prevent use of amenity space.
• C, Manage: on site with low impact.
• D, Report: off site, within 3 m of the boundary.

The off-site trigger fell from 7 m to 3 m. RICS says knotweed rarely causes structural damage to substantial buildings. Older pages that mention risk categories 1 to 4 and 7 m are out of date.

Choosing a knotweed contractor

Look for a management plan with an insurance-backed guarantee, which is what many lenders want. Neither body below is a licence; they are trade associations with audited standards.

• PCA members are audited, and the PCA runs knotweed courses for surveyors and technicians, including the CSJK qualification.
• INNSA (Invasive Non-Native Specialists Association) members follow its Code of Practice for Managing Japanese Knotweed and can provide insurance-backed plans that lenders accept.

Ask for a written plan, the waste carrier registration number and the guarantee terms. See what removal costs.

Neighbours and councils

If knotweed spreads from your land, a neighbour may bring a private nuisance claim. Network Rail v Williams (2018) is the leading case, and RICS notes that neighbour claims are a risk. Councils do not treat knotweed on private land. Your council will not treat knotweed on your property; it is the landowner's job, though the council can issue a community protection notice if it spreads. See council pest control.

Japanese knotweed in the garden

Garden knotweed is often first noticed in spring, as red-purple shoots, then fast growth into tall hollow canes. Do not cut, dig or compost it: fragments as small as 1 cm can regrow.

Photograph the plant and send it to a surveyor to confirm. Then choose a plan: herbicide over three to five years, or excavation. Record it on the TA6 if you sell. Having it is not an offence, but you must stop it spreading into the wild or onto neighbouring land. Book a survey if it is near a boundary or a drain.

Knotweed in the lawn

Knotweed shoots can come up through a lawn from rhizomes below, sometimes some distance from the visible stand. Mowing or strimming chops the plant and spreads fragments, so stop mowing that area until it is identified.

Lookalikes such as bindweed are far more common in lawns, so confirm the plant first. If it is knotweed, a contractor will map the rhizome spread before treatment. Never put cuttings or turf in a green waste bin; they are controlled waste. Mark the area with canes so everyone in the household knows to keep clear until a surveyor has seen it.

Knotweed near a wall or the house

RICS says knotweed rarely causes structural damage to substantial buildings, but it can damage paths, drains and walls. The bigger cost often comes from the reaction of lenders and buyers.

If it shows visible material damage to a structure, RICS Management Category A applies. If it sits within 3 m of your boundary, even on a neighbour's land, it still matters for the TA6 and for RICS Category D. Get a specialist survey and a written plan, preferably with an insurance-backed guarantee.