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The unwanted visitor hiding in your garden

Identifying Japanese knotweed ought to be straightforward.  After all, the plant has a very distinctive leaf shape which is shield-like in appearance, the leaves emerge from nodes in a zigzag pattern and it has large green stems with purple speckles.  These are notable characteristics to aid in identifying any plant.

Setting aside related species such as Giant and Bohemian (hybrid) knotweed, plants that create the same issues for property owners, Japanese knotweed can appear quite different dependent on the time of year, or whether they have been previously treated. Our guide: ‘How to Identify Japanese knotweed’ covers the various stages of growth, but one of the most notable points of difference can become evident after Japanese knotweed has been treated.  Knotweed (Japanese, Giant & Bohemian), can re-merge in bonsai form after treatment with a glyphosate-based herbicide such as ‘Roundup’, which is the most commonly used professional and commercial product.

What to look for:

Bonsai knotweed shares characteristics with the untreated plant; the leaves have a similar shape, but frequently appear in miniature form and may be more pointed, twisted and wispy in appearance.  The plant tends to be bushy in appearance and will form a small tight clump, which could grow to become healthier in appearance but will not reach the lofty heights of untreated knotweed (2m+).  It is also likely that more reds/purples will be visible along stems and leaf edges, indicating that the plant is strained.

What does this mean?

For the owner of a new property, if this was not highlighted when the seller completed their TA6 form, this could indicate that the previous owner was aware that Japanese knotweed was present and decided to treat it either professionally or themselves (with a commercially available dilution). If that is the case, and this was disguised, the new owner may have scope for legal recourse.  For commercial or property developers, misidentifying the plant could create issues further down the line if a development takes place on live knotweed.

If you require help identifying Japanese knotweed, we are always happy to do so as a complimentary part of our service.  Simply email the photo to management@jkmknotweed.com and we will respond with our assessment.

Our initial interaction with clients usually starts with the subject of Japanese knotweed identification. Photos sent are examined, and sites visited to determine whether the species in question is Japanese knotweed. In some instances it could be a hybrid, or simply a similar looking plant.  We are always happy to do this, however we thought it would be great to provide a guide to the identification of Japanese knotweed. We thought that this would help you to determine for yourself whether the plant is present.  It would also enable you to understand more about the issues associated with the plant and its various treatment methods.

Japanese knotweed emerges in the spring as small asparagus-like shoots that unravel to reveal red/purple leaves and stems.  As the plant matures it forms purple speckled canes that are similar to bamboo. A zigzag leaf structure then emerges from the nodes displaying the familiar shield-shaped leaves.  In the summer Japanese knotweed can reach a height of over 3 metres, with masses of green leaves and clusters of tiny creamy/white flowers.  Yet despite falling back to a crown of broken stems in the the autumn/winter months, the plant will return with renewed vigour the following season. Energy from the growth above ground is drawn back into the root or rhizome in readiness for the spring.

There is a lot to admire about the Japanese knotweed plant, however its resilience is the main reason that it creates problems for people.  The botanist who introduced the species extracted his samples from the side of a volcano.  It’s ability to deal with harsh terrain and put down root network earned the admiration of the railway industry who used it to shore up embankments.  These days it can make it difficult to obtain a mortgage and can prevent you from developing land. For this reason it is useful to understand the basics  of Japanese knotweed identification.

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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.

In recent days, the story of Birmingham couple Nasreen and Sajid Akhtar has made it to many of the UK’s leading publications. Their inability to sell their home because of their neighbour’s Japanese knotweed infestation was first reported in the Sunday Mail, then The Telegraph and The Sun picked up the story the next day. Radio 2’s Jeremy Vine even devoted a segment of his show to it, on which our very own Simon McGuigan offered advice and timelines dealing with the problem.

There is no doubt that it is a dramatic story, Mrs Akhtar is pictured surrounded by Japanese knotweed that trails over her neighbour’s fence. The story has obviously created a great deal of awareness about the plant and the problems that it can cause. However, the trouble is a lot of the information quoted isn’t sensible or accurate: (more…)

Japanese knotweed

It is difficult to think of a plant that has seen more of a reversal in popularity than Japanese knotweed.  It arrived during Queen Victoria’s reign to plaudits and even awards.  Broad heart shaped leaves and the delicate little white flowers soon made it popular with gardeners and horticulturalists, whilst its fast growing root structure and thick bamboo style stems earned the species a role shoring up the coal pits and railway embankments of Europe.

From this auspicious start Fallopia japonica has become a reviled plant, or weed.  Today people are reticent to mention it, and when they do it evokes worry, sometimes fear.  The benefits of this plant have long been forgotten, because it is an example of the introduction of a non-native species that is right up there with the Cane toad in terms of success.  Both had a job to do in their early years, until it was realised that the detriment far outweighed the benefits. (more…)