A Japanese Knotweed infestation is fully grown by early summer and bamboo like stems are hollow with underground stems and distinctive purple speckles and they form dense stands up to 3 metres high. This plant flowers in late summer and consists of clusters of spiked stems covered in tiny off white blooms. Although the plant can be a pest, it does provide a good source of nectar for many insects.
The long canes can arise from the rhizome which grows underground from an existing crown, where previous growth has been present, or from a cut stem. During the late autumn, the leaves fall and the canes die down and turn brown. The canes will remain standing throughout the winter and can often still be seen in new stands in the following spring and summer.
The rhizome is the underground part of the plant. It is knotty with leathery dark brown bark and when fresh snaps like a carrot. Underneath the bark it is orange or yellow in colour. Inside the rhizome is a dark orange brown central core or sometimes it is hollow with an orange, yellow or off white outer ring, although this is variable. Young rhizome is very soft and white. The knots are nodes, spaced at 1-2cm intervals where there are often small white fibrous roots or buds emerging. Each of these ‘knots’ can potentially grow into a new plant if the rhizome is cut up.
Japanese Knotweed thrives, anywhere and everywhere. It will continue to thrive, given half a chance, despite recent legislation strictly controlling the transportation and disposal of stems, roots and infected soil. Treating Japanese Knotweed is very difficult so you really should consider Japanese Knotweed removal. This is where JJB Ground Care can help if you want to get rid of Japanese Knotweed.