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Japanese Knotweed

Japanese Knotweed

Giant Hogweed

Himalayan Balsam


Aquatic weeds

Japanese Knotweed (Fallopia japonica) was brought into the UK by the Victorians as an ornamental plant. Its native environment of Japan, China and Korea is on slopes of volcanoes were the soil is very infertile and does not allow for rapid growth, The plant also has insects and fungi that feed off it which has a controlling effect. In the UK Japanese Knotweed has no natural predators and thrives on our fertile soils.

At present only female plants are growing in the UK and the seeds are not fertile. The plant spreads from either the rhizome being moved or part of the green plant being broken off and transported by natural or mechanical means. The most common ways of the plant spreading are on water ways in flood conditions and fly tipping.

Japanese Knotweed is now a massive problem and is one of the most invasive species that we know have in the UK, it is estimated that the cost to eradicate it is £1.56bn. It is listed in the wildlife and Countryside act 1981 and all parts of the plant are considered as controlled waste under the Waste Regulations.


The plant starts to grow in early spring producing a small red bud from either the crown root or any exposed part of the rhizome. The early growth looks similar to an Asparagus spear. The plant is very rapid growing and soon produces a green heart shaped leaf, if the plant is growing under stress this can sometimes by a ready brown colour. The Stem is green and has brown speckles on it. In the late Autumn a creamy white flower grows. As soon as the plant is exposed to a frost it starts to die back leaving dead bamboo like canes. That is the end of the life of the above ground plant although the EA still stipulates that even though dead, the material must be treated as controlled waste.

The Rhizome under ground can grow up to and sometimes exceed 3m down and 7m out from the crown root. The rhizome is a distinctive orange colour when snapped.

UK Weed Control services

UK Weed Control use the TCM hit system to eradicate Japanese Knotweed. This system has been developed over many years of successful Japanese Knotweed eradication by TCM.

In Situ Spraying Single season

Using TCM s HIT system we can eradicate Japanese knotweed in one growing season providing that the plant is not deemed as being close to a water course or near desirable vegetation that will be affected by the residual herbicide that we use.

In Situ Spraying 2 year

If the Japanese knotweed is near to a water course or is amongst desirable vegetation we use non residual herbicides, this process requires more visits and is spread over two years. We have had some success in killing the Japanese Knotweed in one year using this system but we always allow our selves two years. We will obtain the required licence from the EA to spray on or near the water.

Integrated on site treatment

This system is usually used on development sites where Japanese Knotweed is in the way and there is no time for a spray programme. The contaminated soil is excavated under our supervision to ensure that all of the rhizome is removed, and then moved to an area within the boundary of the site where construction work will not be impeded. The contaminated soil is then treated as we would with an in situ programme.

On Site Burial Cell Encapsulation

If space is not available for the above method, the Japanese Knotweed can be buried in a sealed membrane cell 2m below the surface, this will be located away from the building footprints. The Japanese Knotweed and contaminated soil is excavated under our supervision and placed in a membrane lined pit and then sealed by heat welding all the joints making escape of Japanese Knotweed impossible

Dig and Dump

We see this as a last resort option. The contaminated soil is excavated and taken away to landfill which in itself is very expensive, the EA guidelines are that you should dig out 7m past the piece of Visible Japanese Knotweed and 3 m down. In most cases this is excessive but it has been known to have go down as far as 5m. Our careful supervision and guidance of the excavation can dramatically reduce the amount of soil going to landfill and as a result dramatically reduces costs.