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What is Japanese knotweed?

Japanese knotweed is one of a number of invasive plants that can cause problems to your property:

● It’s a large clump-forming plant, which grows up to 3m tall, with light green shield-shaped leaves with a flattened base, approximately 10-15cm long.
● The stem is hollow, bamboo-like, light green speckled with pink-red.
● There are only female plants in Britain, so no viable seeds are produced.
● The flowers are tiny and clustered together in creamy-white sprays, present from August to October.
● It produces thick and extensive roots called rhizomes, orangey-yellow inside, and spreads by fragments of rhizome. A piece the size of your thumbnail is sufficient. Fragments of rhizome get picked up in soil and on equipment.
● Over the winter the plant dies back leaving tall brown canes but as a perennial plant its top growth is renewed each year from the rhizomes which can spread relentlessly.
If you believe you have Japanese Knotweed please log on to for further information.
For more information on Japanese knotweed and other invasive species, please visit the NI Direct website.