Japanese Knotweed (Fallopia japonica)

Japanese Knotweed has become the most invasive plant in the United Kingdom. First introduced to the UK by the Victorian’s as a spectacular horticultural specimen, it then spread to the countryside in the early 1900’s. Since then it has spread the length and breadth of the country.

All plants in the UK are female and need to be fertilised by the male plant which was never introduced to the UK. This means that the plant has spread by vegetative means alone, meaning that all new plants are created by existing foliage and rhizome (root).

How to identify Japanese Knotweed

Japanese Knotweed

Giant Hogweed

Common Ragwort

Himalayan Balsam

Buddleia

Aqautic Invasive Weeds

spring

summer

flowering

winter

Why is it a problem

It is difficult to control as it can spread rapidly, stands of Japanese Knotweed have an extensive underground rhizome network and will extend several metres around and beneath depending on ground conditions. It only takes a tiny fragment of rhizome or stem to grow to form a new plant.

It is a threat our native species, as it out competes them. It can cause damage to an urban infrastructure, growing through tarmac and breaking concrete. On canals and rivers it can cause erosion, as once the plant dies back in the winter the banks are vulnerable to collapse.

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