Japanese Knotweed Removal

Japanese knotweed is a giant weed (herbaceous perennial) that grows up to 10cm a day in any type of soil. It originated in Asia where it thrives on waste ground and on its natural habitat on the side of volcanoes. In Asia, there are bugs that control the knotweed but in the Europe and the USA these bugs do not exist and removal is needed.

Removal methods

Knotweed removal relies on both the treatment of the foliage growing out of the soil and root system that grows under the soil. The underground root system can grow up to 7 meters away from the main plant so an extensive removal plan is needed.

There are a number of main removal methods.

Herbicide Spray

Using a herbicide spray to kill it is the most efficient removal method. Spraying the entire plant from top to bottom will eventually kill it as the spray will be absorbed by the plant and get into the root system.

However, a herbicide spray will generally take three to four growing seasons to completely remove it.

Excavation & Removal

If using a herbicidal spray is impossible (i.e. it is closer to a river or other water source) then it can be excavated and taken to a licensed landfill site. This removal method involves digging up the entire plant and root system and is a costly method of Japanese knotweed removal.

Root barrier

A root barrier can be installed that will encapsulate the knotweed on site. This knotweed removal method can be used if a neighbour has knotweed that is close to your own land but your neighbour does not want to pay for its removal.

Soil sifting

Soil sifting is a knotweed removal method where all the knotweed infested soil is mechanically excavated and then sifted through to separate the parts of Japanese knotweed from the soil.

How to remove it

Knotweed removal is a difficult thing to do by yourself although it can be done. If you are excavating knotweed yourself then the most important thing is to ensure that you remove every single piece of knotweed. If you do not, even a piece the size of your fingernail will grow into a whole new plant.

Knotweed is a very resilient weed and infestations spread rapidly. Often you will see an infestation that has been spread by the property owner because they have tried to remove it by themselves and have missed some. It is recommended that you bring in a specialist to evaluate the infestation to undertake a survey.