So where did Japanese knotweed come from? How did it get here? Why is it a problem? These are questions that many people have been asking for a long time.
Japanese Knotweed is a highly invasive plant and is recognised as the most invasive species of plant in Britain today. It originates from Asia and was introduced to the UK back in 1824 as an ornamental plant and also a source of cattle feed. Japanese Knotweed is now abundant throughout the whole of the UK.
Japanese Knotweed is a tall perennial plant. This means that it dies back in winter and re-emerges in spring. The shoots start to emerge in late March / early April, are asparagus like and are a red-green colour. As it grows through the summer the red colour turns into red speckles on an otherwise green stem. At full height it can reach up to 3m.
The leaves are bright green and roughly hand sized in an almost heart shaped fashion. In September the plants develop small white flowers which in some cases can be so abundant that they almost completely cover some sections of the plant.
Around November time the plant drops its leaves and flowers. The hollow brown and brittle stem remains as a clearly visible indicator of where the plant stood in the summer. The next year the plant will re-grow from the same spot out of what is known as the crown.
Japanese Knotweed is a resilient plant that, in the UK and Europe, only spreads via the movement of its Rhizomes. The Rhizome, according to The Environmental Agency Guidelines, can grow to a depth of 3m or more and up to 7m away from the plant.