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 firstname.lastname@example.org and we will respond with our assessment.