HOW TO IDENTIFY JAPANESE KNOTWEED

When it comes to Japanese Knotweed identification, the different seasons throughout the year have a large part to play.

Japanese knotweed growth is usually at its most prolific from April to October, but mild winters and warm damp summers in recent years have seen the growing season extended. Early signs of growth are now seen in mid-March and new shoots have even been identified as late as November. This is why Japanese knotweed treatment or removal programmes often have to be reviewed annually to ensure the methods being used will continue to be effective.


HAVE YOU HAVE IDENTIFIED JAPANESE KNOTWEED?

Have you seen a suspicious looking plant growing on or near your property and want to know whether it is knotweed? Check the photographs and descriptions below below to see if they look familiar.

JAPANESE KNOTWEED IN SPRING

When trying to identify Japanese Knotweed in spring, look out for new shoots that are red/purple in colour and look like thick asparagus spears. As Spring continues these fast growing canes will get larger and begin to develop leaves that begin to unroll as the plant turns green. In late spring, the canes will look more like bamboo and have a characteristic purple speckles with a distinctive zigzag pattern on the stems

JAPANESE KNOTWEED IN SUMMER

When trying to identify Japanese Knotweed in summer, look out for the plants with a dense cluster of stems with a lot of foliage are a height of approx. 2-3 metres. In summer Japanese knotweed stems will have a bamboo-like appearance and if broken, are hollow inside. The leaves will now have a distinctive spade shape with a pointed tip. Between August and October, the plant will have tiny white flowers.

JAPANESE KNOTWEED IN AUTUMN

In Autumn, Japanese Knotweed will share a lot of similar traits with summer growth. It still have a very dense cluster of bamboo stems with a lot of foliage with that distinctive heart shape leaf with a pointed tip. However, the leaves will begin to turn yellow in colour and wilt. The hollow bamboo-like stems will also change colour from reddish brown to a darker brown.

JAPANESE KNOTWEED IN WINTER

Identifying Japanese Knotweed in winter is harder than in other seasons due to the death of foliage. That said, you can still identify the brown canes that are more or less decomposing.
The canes are hollow, collapsing and intertwining on top of one another. Quite often, you will see canes from previous years, at a different stage of decomposition, underneath the recent growth. Towards the end of winter you might see shoots of next season’s Japanese Knotweed underneath the decomposing foliage.


DO YOU NEED PROFESSIONAL HELP WITH JAPANESE KNOTWEED?

If you are still unsure whether or not Japanese knotweed poses a threat to your property and you want to speak to an expert, simply contact us online, find your local branch or call us today and speak to one of our qualified and experienced Japanese knotweed experts.

Alternatively, you can always fill in the form below to request a knotweed survey and have one of our Knotweed specialists take a look.

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.