Distribution of Japanese knotweed

Japanese knotweed is still spreading rapidly despite our best efforts. Since its introduction the species has spread throughout the British Isles, only the Orkney Islands are exempt. 

Its distribution also covers much of mainland Europe from southern France and northern Italy to Norway. Beyond Europe it is found in many states in the USA from California to Washington and throughout Canada and is increasingly being reported as a nuisance weed in New Zealand and Australia.  

The spread of Japanese knotweed across the British Isles

1900                                        1940

1970                                        2012

All data maps on this page - © Crown Copyright. All rights reserved NERC 100017897 2004 & NBN Gateway