It’s winter, and while many weeds appear dormant above ground, Japanese knotweed remains very much alive below the surface. Its extensive network of underground stems (rhizomes) stores energy over winter, allowing it to sprout vigorously in spring and outcompete other plants for space, light and nutrients.

How did Japanese knotweed get here?

Japanese knotweed (Reynoutria japonica) is an invasive non-native species that was introduced to the UK in the mid-19th century by German-born botanist Philipp von Siebold as an ornamental garden plant. Gardeners admired its bamboo-like stems and rapid growth, and it spread widely before its invasive nature was fully understood.

Why is Japanese knotweed considered problematic?

Japanese knotweed does not pose a direct toxic threat to humans or animals, but it can be highly disruptive in several ways:

• It forms dense stands that outcompete native and desirable garden plants.
• It has fibrous rhizomes that can extend widely underground and regenerate from tiny fragments.
• It is listed under UK law as an invasive species, and landowners are expected to control it responsibly so it does not spread to neighbouring land or wild habitats.

The belief that Japanese knotweed routinely causes structural damage to buildings is widely held, but recent guidance and research suggest this risk may be overstated in many cases. While knotweed can exploit existing cracks or weaknesses in hard surfaces, evidence for direct destruction of sound building structures is limited — and lenders and surveyors increasingly focus on impact assessments rather than fixed distance rules.

Where knotweed affects property transactions, the issue is often more about market perception and financing requirements than guaranteed physical structural damage. Properties with knotweed can be harder to sell because lenders may require proof of a management plan before granting a mortgage, and buyers are often cautious.

In my case, it was ultimately more trouble than it was worth to fix the damage done to my property. Luckily, I was eventually able to sell my house easily and for free with the right platform. These sites are handy as they will briskly give you a cash offer without the flat fees you’d get with conventional estate agents, regardless of the state of your home. You then complete the sale in your own timeframe.

Ideally, of course, we wouldn’t have to deal with such consequences in the first place. So, to conclude, let’s explore a few possible ways of alleviating your knotweed situation.

How to get rid of Japanese knotweed

Hire a specialist

Professional contractors with expertise in invasive plant control generally achieve the best long-term results when eliminating Japanese knotweed from your garden. They can implement and oversee a management plan using appropriate herbicide applications or other methods in line with UK law and guidance.

Herbicides

Japanese knotweed is most effectively treated with approved, regulated herbicides, often glyphosate-based products applied at the right time of year (typically late summer to autumn). Repeat treatments over multiple seasons are usually necessary, and professional application by qualified operators is recommended. Home garden products are often not strong enough to eradicate mature infestations.

While some gardeners and organisations discourage indiscriminate herbicide use, targeted treatment of Japanese knotweed is recognised as a practical control method when integrated with a wider plan.

Excavation

Digging out knotweed can be very difficult because rhizomes can extend deep and far from visible growth. If excavation is attempted, very small fragments left behind can regenerate, so this method alone is often ineffective without careful follow-up.

Legal and disposal considerations

Japanese knotweed and soil containing its rhizomes are classified as controlled waste under UK law. You must not dispose of it in home compost bins, green waste collections or regular household rubbish. Instead, material usually needs to be taken to an authorised landfill or disposal facility using a registered waste carrier. Improper disposal can lead to legal penalties.

Landowners are legally required to prevent knotweed from spreading into the wild or onto neighbouring properties and can face fines or other enforcement action if they fail to manage infestations responsibly.