Where Can I Find Knotweed?

by | Last updated on January 24, 2024

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Japanese knotweed can be found in the U.S. in

42 states coast to coast except the arid Southwest

, several of the deep South Gulf states and the highest of the Rocky Mountains. It is also in eight Canadian Provinces.

Where does knotweed grow in the US?

So far, its infestation has been limited mostly to the northeast. But knotweed is found in every U.S.

state except North Dakota, Nevada, Arizona, New Mexico, Texas, Florida and Hawaii

, according to the University of New Hampshire Extension.

Is knotweed illegal?

Knotweed & the Law

Under the Wildlife and Countryside Act 1981 section 114 (2) (WCA 1981) Japanese knotweed is classed as a controlled . Therefore,

it is not illegal to have knotweed on your property

, but it is against the law to cause or allow the plant to spread in the wild.

Is Japanese knotweed in the US?

Japanese knotweed

occurs across the U.S.

and has been reported to be invasive in natural areas throughout the northeast into Georgia and west to Missouri, with additional infestations in Oregon and Washington.

Why is Japanese knotweed illegal?

You must prevent Japanese knotweed on your land spreading into the wild. Soil or plant material contaminated with non-native and invasive like Japanese knotweed can

cause ecological damage

and may be classified as controlled waste.

Is it illegal to plant Japanese knotweed?

It is not illegal to have Japanese knotweed

on your property, but it is illegal to allow it to spread into the wild or on to neighbouring properties. … So, technically, it's not illegal to plant Japanese knotweed on your own property, but the moment it spreads outside of your property you are breaking the law.

Is it illegal to have Japanese knotweed in your garden?

Is it illegal to not report Japanese knotweed in your garden?

It is not illegal to have Japanese knotweed

in your garden, or on your land. If you have discovered the plant on your land then you are under no legal obligation to notify anyone about it or even treat the plant.

What to do if a Neighbour has Japanese knotweed?

What to do if your neighbour has Japanese knotweed? If your neighbour has Japanese knotweed, then you should tell them

as soon as possible

. If they do not arrange to have the Japanese knotweed treated and allow the Japanese knotweed to spread to your land, then you may able to bring a claim against them.

Do you need a license to remove Japanese knotweed?

If you have spotted Japanese knotweed on or near your property and are wondering if you need a licence to remove it – in short, no you don't. …

Currently, there is no legal obligation to remove or treat knotweed

, just as long as you're not encouraging or allow it to grow.

Can you remove Japanese knotweed yourself?

Can I get rid of Japanese Knotweed myself?

Treating Japanese Knotweed yourself is possible but can be difficult and time consuming

. Japanese Knotweed grows up to 10cm a day, so it is essential that you are quick and effective with removal.

Why should you not cut Japanese knotweed?

People trimming and cutting back hedges should not cut Japanese knotweed,

as the plant is spread by fragments which easily take root

. That's the advice from Colette O'Flynn, invasive species officer, National Biodiversity Data Centre, who pointed out the plant is usually spread inadvertently by people.

What eats Japanese knotweed?


tiny psyllid

feeds on the sap of the invasive knotweed. … But the Japanese knotweed psyllid promises to be a formidable match for this tough invasive plant. Psyllids feed on the sap of the knotweed, diminishing its energy supply and ultimately killing the plant.

Why is knotweed bad?

Japanese knotweed is very dangerous because of

its ability to cause devastating costly damage to its surrounding environment

through its vigorous rapidly growing root system that frequently damages property foundations, flood defences, and pavements with some plants invading houses.

Who is responsible for getting rid of Japanese knotweed?

Japanese Knotweed is classified as an invasive species it is therefore the responsibility of

the land owner

to prevent the plant spreading to neighbouring land (or into the wild), and removal of plant must be conducted with due care and attention.

Do you have to declare knotweed?


sellers are legally obliged to declare it if they know knotweed is present on the property

. Secondly, if it's visibly growing above ground, a surveyor should identify it during a survey.

How long does it take to treat Japanese knotweed?

q16: How long does it take to eradicate Japanese knotweed? It can take

up to 5 years

to completely remove Japanese knotweed through chemical treatments. However, it can be eradicated immediately through excavation, which involves digging it up out the ground.

David Martineau
David Martineau
David is an interior designer and home improvement expert. With a degree in architecture, David has worked on various renovation projects and has written for several home and garden publications. David's expertise in decorating, renovation, and repair will help you create your dream home.