At SE Knotweed, our knotweed FAQ hub answers the questions homeowners and buyers ask most, from whether it is illegal to have knotweed to what removal costs and how it affects a sale.
Knotweed removal costs from around £1,200 for a herbicide programme to £12,000 for full excavation, and a survey from £150 to £500, all confirmed once the stand is measured on site.
Having Japanese knotweed on your own land is not an offence, so you cannot be prosecuted simply for it growing in your garden. What the law controls is spread: under the Wildlife and Countryside Act 1981 it is an offence to plant it or cause it to grow in the wild, and the Anti-social Behaviour, Crime and Policing Act 2014 allows a notice where spread affects a neighbour.
The soil around a stand is also controlled waste under the Environmental Protection Act 1990. So the honest position is that you may keep it, but you must not let it spread or dispose of the waste carelessly. Our law pillar sets the position out in full.
Knotweed removal costs from around £1,200 for a herbicide programme on a small stand to £12,000 for full excavation on a large or awkward site, and a survey costs £150 to £500. The figure is driven by the method, the size of the stand, machinery access and whether soil leaves the plot as controlled waste.
We measure the stand at survey and give a fixed price rather than a headline rate, and we often credit the survey fee against treatment. The cost pillar breaks the figure down by method and size so you can see what drives it.
You get rid of Japanese knotweed by killing or removing the rhizome, because cutting the visible canes alone does nothing lasting. The methods are a herbicide programme over several seasons, full excavation and licensed disposal, on-site relocation to a buried cell, or a root barrier to contain spread.
The right one depends on your timescale, whether the soil can stay on the plot, and your budget, and we confirm it at survey. Our treatment hub explains each method, and the how to kill it page covers the herbicide side in detail.
Knotweed can hold up a mortgage or sale because a valuer flags it as a risk, but it rarely stops one outright. Most lenders proceed where there is a management plan from an accredited firm and an insurance-backed guarantee that would fund further treatment if the plant returned.
You must also declare it on the TA6 form when selling, and since 2020 you may only answer No if certain there is no rhizome within 3 metres of the boundary. Our mortgages page explains what a lender needs and how a guarantee unblocks a stalled sale.
Japanese knotweed is identified by its zig-zag green stems flecked with purple, its shovel-shaped leaves set in a staggered pattern along the stem, and its creamy-white flower sprays in late summer. In winter the canes turn brown and hollow but stay standing, and the rhizome is alive below ground.
Several garden plants are mistaken for it, so a confirmed identification settles the question before any money is spent. Our identification guide shows the seasonal signs and the look-alikes, and you can send us a photograph to check.
Knotweed spreads from rhizome and stem fragments moved in soil and water, not from seed in the UK, which is why a cut or dug stand can seed new growth and why the soil is treated as controlled waste. It exploits existing cracks, drains and gaps rather than breaking sound structures.
The RICS 2022 standard states that sound, modern foundations are unlikely to suffer structural damage from knotweed. Our spread page explains the mechanism, which is what shapes both the treatment and the disposal rules.
You use an accredited specialist because a lender only accepts a management plan and guarantee from an audited firm, and that acceptance is the point of the work when a sale is involved. We hold PCA approval, TrustMark registration (licence 2902558) and the CSJK surveying qualification.
An accredited firm can issue the insurance-backed guarantee a lender relies on, dispose of contaminated soil lawfully, and produce a report a valuer and solicitor can act on. The PCA-approved contractor page explains what the accreditation means in practice.
Tell us the address and what a surveyor flagged. We confirm the plant, record the RICS category and set out the figures.