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Japanese Knotweed - Common questions

How much is the treatment? 

Prices will vary depending on the size of the area to be treated. Please check our Prices page for more information

What does Japanese knotweed look like?

Japanese knotweed emerges as small asparagus-like shoots green/purple in colour. As the plant develops it produces small red/green shield-shaped leaves growing from the stem’s many distinct raised nodes or ‘knots’. Once mature, the leaves become a vibrant green colour reaching lengths of up to 120mm. 

The red/green stems of adult Japanese knotweed have a hardy bamboo- like appearance which grows in thick clumps or ‘stands’. During the months of September and October, creamy white flowers are produced, growing in clusters at the end of the stems.

As the plant sheds its leaves and dies off, the stems become hollow brown skeletal remains that are easily broken. The dead stems often remain upright amongst new growth during the following season. How to identify Japanese Knotweed (

Why is Japanese knotweed a problem to property?

Japanese knotweed can grow very quickly, and because of this rapacious growth, it has been known to cause damage to building structures and substructures by targeting weak points, such as cracks in masonry, and attempting to grow through them.

How is it spread?

Japanese knotweed can produce seeds, but it is rare for these seeds to germinate.

New plants will grow from the underground stem (rhizome) and the nodes on pieces of green stem.

Is Japanese knotweed poisonous?

Japanese knotweed is not poisonous and is not harmful to touch, however, always use caution to avoid inadvertently allowing the infestation to spread.

Japanese knotweed is spreading onto my land from other land

Although it is not illegal to have Japanese knotweed growing on your property, allowing Japanese knotweed to grow from one property onto other people’s property may be regarded as a private nuisance. This would be a civil matter under common law.

If you think that you are at risk from Japanese knotweed on neighboring property, consider contacting the property owner directly or via a solicitor to explain your concerns.

How do I control Japanese Knotweed on my land?

It is highly recommended not to treat Japanese Knotweed yourself, as ineffective treatment can lead to further spread and could be potentially dangerous to humans, pets and wildlife.  Please contact us for a free quotation.

How many treatments will it take?

This will depend on the severity of the growth.  2 or more treatments are often required. Annual treatments are needed for as long as the plant is growing, with monitoring for new growth required for a number of years thereafter. Treatment and monitoring plans are usually between 5-10 years.