About Japanese knotweed

Japanese knotweed, also referred to as Polygonum cuspidatum, Reynoutria japonica and Fallopia japonica, is a highly invasive perennial weed that is spreading throughout the UK at an alarming rate.

Knotweed can grow up to 3 metres high and grows extremely quickly. It can grow under foundations, driveways, as well as through buildings. If there is a weakness, knotweed will exploit it.

If you've spotted a suspect plant take a look at our Identification Video above, this shows what knotweed looks like during the different seasons, and some plants that commonly get mistaken for Japanese knotweed.

We've also produced a Japanese Knotweed Identification Guide, which you can download to help you identify the plant on site. It is relatively easy to identify Japanese knotweed if it hasn't been concealed.

Identifying Japanese knotweed

In spring time you will be able to see red or purple shoots appear from the ground. These will rapidly begin to grow into long canes which over time will turn green in colour.

Japanese knotweed is fully grown by early summer. The plant flowers in late summer and these consist of clusters of spiky stems covered in tiny creamy-white flowers. The leaves are luscious green in colour and usually flat and often shovel or heart shaped in appearance.

In late autumn the leaves will fall to the ground and the cane becomes dark brown in colour. Japanese knotweed remains dormant over the winter months.

If you are still unsure, we offer a Japanese knotweed identification service. Email your photos to expert@environetuk.com and we'll tell you if Japanese knotweed is present. This is a free service. However, if you would like to make a small donation to a worthy charity via JustGiving that would be appreciated.