Japanese knotweed: what the law expects and how professionals deal with it
By the Offrano editorial team · · 4 min read
Few garden plants cause as much anxiety as Japanese knotweed. It grows fast, regrows from tiny pieces of root and comes up in property surveys. The legal position is more measured than its reputation suggests: you do not have to remove it, but you must not let it spread off your land or into the wild, and knotweed waste is subject to strict disposal rules. This guide sets out the duties in England, how treatment works in outline, and what to look for in a specialist.
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Why knotweed is treated differently
Government guidance describes Japanese knotweed as the most common of four invasive knotweeds in England. It spreads through direct rhizome growth and through fragments of stem and rhizome: a new plant can grow from a piece of rhizome as small as 1 cm. That is why digging, strimming or moving soil without care tends to make the problem worse, and why contaminated soil and plant material may be classified as controlled waste.
The rhizomes can extend underground well beyond the visible canes, which is also why a professional survey looks wider than the patch you can see.
Source: gov.uk
Your legal duties
You must stop Japanese knotweed on your land from spreading off your property. You do not legally have to remove it from your land unless it is causing a nuisance, but you can be prosecuted for causing it to spread into the wild. A neighbour affected by knotweed spreading from your land may also have a private claim, and councils can use anti-social behaviour powers in some cases.
If you are selling a home, the standard property information forms ask about knotweed. Answer them honestly; a treatment plan from a specialist, with its guarantee, is what buyers and lenders usually want to see.
If knotweed is growing into your garden from next door or from public land, start by telling the owner in writing, with photographs and dates. Councils and railway or highway authorities often have their own knotweed management programmes and will want to know.
Source: gov.uk
Treatment in outline
Government guidance says not to treat knotweed yourself unless you have the appropriate skills and experience. Professional options include herbicide treatment over several growing seasons, excavation and removal off site, and burial or containment on site under controlled conditions. Chemical treatment may require a certificate of competence for herbicide use, a hazardous substances assessment, permission from Natural England in protected areas and agreement from the Environment Agency near water.
Which option suits depends on the timetable: a building project that needs the ground cleared this year usually means excavation, while a garden with time to spare can be treated in place. Treatment rarely finishes in one visit; ask how many visits are included and how regrowth is dealt with.
Source: gov.uk
Disposal: where most mistakes happen
Knotweed must not go in green waste bins or be mixed with other surplus soil, and contaminated soil must not be sold as topsoil. If it cannot be dealt with suitably on site, it must go to a landfill or incineration facility with the correct permit. Before transfer, the site must be told and asked whether it can accept it, and the waste must be covered or enclosed during transport. Vehicles must be cleaned afterwards so no fragments escape.
Dead brown canes cut at least 10 cm above the crown can be composted on site. Individuals who want to burn knotweed only need to check with their council that burning is allowed, but crowns and rhizomes may survive burning, so the remains still need proper disposal.
- no knotweed in council green waste or household bins
- no mixing with other soil, and no sale of contaminated soil
- transport covered, to a permitted site that has agreed to accept it
- vehicles and tools cleaned after handling
- waste carried by a registered waste carrier
Choosing a specialist
Government guidance suggests looking for contractors with accreditations such as Amenity Forum membership and the BASIS professional and amenity registers, and notes that many belong to trade bodies such as the Invasive Non-Native Specialists Association or the Property Care Association. Ask for a written management plan, the method and timetable, how waste will be handled, and what guarantee is offered and whether it is insurance-backed.
Offrano passes your request to exactly one gardening or weed control business in your area, the one that buys it; we email you who it is before it receives your details, and the request is free for you. We do not check trade accreditations, so ask to see them.
Source: gov.uk