Japanese knotweed identification is an important part of what we do, and we are always happy to offer advice, however the information below will give you an indication of what the plant looks like at various times of the year.  As the weed grows it can spread rapidly, therefore early identification is useful in order to contain the spread and remove the plant with more ease.

Japanese knotweed is known for its thick bamboo-like stems and distinctive large shield or heart shaped leaves.  However, this is the appearance once it has reached maturity in the summer months, different features will be observed in the plant as it emerges and matures over the course of a year.


In early spring, rolled red/purple new shoots appear then as the young leaf grows it turns green whilst the veins remain a dark red colour.  These young shoots can grow up to 2cm a day, allowing the plant to quickly establish itself in a new environment.


By the summer, the tall hollow stems of Japanese knotweed can grow up to 3 metres in height.  At this stage the plant is more easily identified, because of those distinctive leaves, purple speckled hollow stems and zig zag leaf structure.

The attractive creamy/white flowers emerge from spiky stems in the late summer, providing an indication of why this once proved a popular plant in the UK, although in this country the plant will not go on to seed.


Towards the end of the autumn, leaves will drop and the crowns that emerged during the summer will die back into a clump of hollow brown stems that have the appearance of bamboo.  The weed can produce new shoots in winter months following a mild autumn.

Contact us today if you need help with Japanese knotweed identification or have concerns about the plant.

Download our guide:

How to identify Japanese knotweed

It provides further information on what to look for at various times of the year, problems associated with Japanese knotweed, treatment methods and other useful sources of information.
A distinctive shield shaped leaf is a pointer for Japanese knotweed identification
A distinctive zig zag leaf structure is a pointer for Japanese knotweed identification