Japanese Knotweed is a tall, vigorous ornamental plant that is believed to have been introduced to the UK by a Victorian horticulturalist in the 19th century. It has since become an aggressive invader in both the urban and rural landscape presenting issues for residential and commercial land owners alike. When left to grow the plant can cause damage to buildings and underground services and will penetrate through damaged foundations and hard standing.

Japanese Knotweed is a member of the Polygonaceae family and it is a rhizomatous (produces underground stems) perennial plant. It has distinctive branching and hollow, bamboo like stems covered in purple speckles. Japanese Knotweed leaves have a distinctive flattened base and pointed tip and in mature plants the leaves can be up to 120mm in length.

A significant characteristic of Japanese Knotweed is the underground network of rhizomes. Japanese Knotweed rhizomes are thick and woody and when broken open an orange centre is exposed. The rhizome network is critical in controlling the spread of Japanese knotweed as it is the main site of regeneration.


Japanese Knotweed can regenerate from less than a single gram of rhizome therefore with a system that has the potential to extend beyond two metres in depth and seven lateral metres from the parent plant careful and informed management is required for its control.

Although Japanese Knotweed is a highly invasive plant, it can be controlled successfully with the correct strategy, including on site treatment using herbicides.

The herbicide is applied to the plant above ground and it is transported throughout the rhizome network which ultimately kills the Japanese Knotweed.

Ash Remediation Management offer treatment solutions in accordance with the Environment Agency’s Code of Practice for the control or eradication of invasive weeds. Our members of staff are fully competent and qualified by the National Proficiency Tests Council (NPTC) to carry out herbicide treatments.