Identifying Japanese knotweed

In spring, red or purple asparagus type shoots will appear, quickly turning into green bamboo-like stems, which grow at a rapid rate, reaching up to 3m in height.

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 canes become dark brown in colour. Japanese knotweed remains dormant over the winter months.

Visit our picture gallery and watch our 3 minute video on How to identify Japanese knotweed. We've also produced a Japanese knotweed Identification Guide, which you can download to help you identify the plant in situ.

If you are still unsure, we offer a Japanese knotweed identification service. Email your photos to 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.

About Japanese knotweed

Japanese knotweed (Fallopia Japonica syn. Polygonum cuspidatum) is a highly invasive non-native weed that can damage foundations and driveways, as well as putting a stop to mortgage applications and construction development plans.

First introduced to the UK from Japan in the 1840s as an ornamental plant, Japanese knotweed is now widespread throughout the UK and can be found as a wayside weed and in many private properties across the country.

Japanese Knotweed Unearthing the Truth

Mortgage lenders require a Japanese knotweed management plan with an insurance backed guarantee to be in place before they will lend on properties with this prolific perennial. Knotweed has the ability to cause significant damage to tarmac, concrete, paving slabs and foundations of properties.

There are also various legal considerations when dealing with Japanese knotweed. Private nuisance claims can be brought against a landowner who allows knotweed to spread into adjoining land. Under the provisions made within the Wildlife and Countryside Act 1981, it is an offence to cause Japanese knotweed to grow in the wild.