What Is Japanese Knotweed?

Japanese Knotweed ShootsJapanese knotweed (Fallopia japonica) is an invasive weed.

It can be identified by white flowers in summer, green stems with red and purple flecks and how quickly it grows. New shoots appear in spring and can look similar to asparagus when they first start to grow.

What Is Japanese Knotweed?


The plant was originally found in Japan and controlled by natural pests and climate conditions. A sample of the plant was bought back to Europe in the Victorian era, where it was planted in gardens, mainly to create themed areas. The plant was found to grow quickly, and by the mid-1800s, was being sold by multiple sellers across the UK.

Since then, the plant has spread across the UK. The rhizomes (underground shoots) can grow to a depth of 2 metres underground, leading to this plant returning each year.


Japanese knotweed damageJapanese knotweed can cause damage to building structures by targeting weak points.

It can grow through cracks in masonry and buildings. The plant will then expand and grow into the crack, causing further structural damage.

During the summer months, Japanese knotweed can grow up to 10cm every day and up to 10-12 feet high. Japanese knotweed is in search of moisture and due to its extreme growth can force its way through paving, walls and more.


Due to the rhizome’s resilience, they can be transported via animals (via the rhizomes being moved via their feet), waterways, railways and main highways. All of these are classed as high-risk areas.

Due to Japanese knotweed’s high growth rate, and the damage it can cause, the weed needs to be declared on the TA6 form. Failure to do so can result in court case. Anti-social behaviour orders (ASBOs) and fines can also be given to individuals who are found to have knotweed in their property which then infects a neighbour’s garden.


Japanese knotweed can be very tricky to identify and remove completely. Treatment is either a 3-year herbicide treatment, or the plant can be excavated. This should only be done by a suitably qualified professional.


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