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Property Surveying Blog
August 19, 2019

I discuss Japanese Knotweed

Written by Sadek Miah

In this blog post I will be discussing Japanese Knotweed. I will be giving an insight into what Japanese Knotweed is, why it is harmful to properties and how it can be eradicated.

What is Japanese Knotweed?

Japanese Knotweed

Japanese Knotweed, otherwise known as Fallopia Japonica is a herbaceous plant and was introduced into the UK in the late nineteenth century.

It is a Bamboo-like plant that grows in large clumps and can even grow up to heights of about 4 Metres.

Japanese Knotweed

The appearance of the plant changes with each season in the UK. In the Autumn months you would typically see white flowers which then dies back down to ground level.

During the Spring and Summer Months the plant grows vigorously achieving heights of around 3 Metres in roughly 10 weeks. The roots of this plant can be as long 20m in length.

Some of the common problems caused by Japanese Knotweed can be seen below:

  • The roots of the Japanese can penetrate through concrete structures. This can grow through paths, roads, patios. Knotweed can exploit joints in brick and concrete paving.
  • The roots can travel through weak joints of drains and can crack and penetrate pipes which can lead to blockages.
  • The growing roots can undermine garden walls and in turn cause retaining walls to collapse.
  • The roots of the Japanese knotweed can destabilize lightweight outbuildings buildings and conservatories. It can sometimes cause these buildings to collapse if they are poorly constructed.

Eradication of Japanese Knotweed

There are several methods to eradicate the Japanese Knotweed. In order for the plant to be successfully eradicated it is essential that there is no trace of the crown, stem or root as this can re grow. Some of the eradication methods can be found below;

  • Excavation of the entire plant from root level which is then buried on a site with a depth of at least 5 Metres encapsulated with a specialist root barrier.
  • Commercial weed killer or herbicide can be used on Japanese Knotweed. It can take slightly longer for this to fully eradicate the plant. Sometimes can take up to 5 seasons to fully kill it. This treatment can be done by spraying the leaves or injecting the stems of the plant with the weed killer.
  • Japanese knotweed has been known to survive burning and can grow back in a matter of days.

If you think you may have Japanese Knotweed on your property, then I would suggest you get in contact with a Japanese Knotweed Removal Specialist for their immediate advice. The longer this is left untreated then the more damage this will cause to your property.