How can I identify Japanese Knotweed?
Paul from Hampstead
19 August 2014
Plants and Gardens questions and answers
I own a house next to a railway line and I’ve recently noticed some leaves on the banks that I think look like Japanese Knotweed leaves. Should I be worried about it? How can I confirm whether it is Japanese Knotweed and, if it is, what should I do from there
There are several plants that look similar to Japanese Knotweed (JK) so first thing to do would be to take pictures and e-mail them to an invasive weed specialist www.innsa.org will give you a list of reputable contractors) and ask for them to identify the plant.
The plant does exhibit seasonal characteristics which are fairly easy to identify:
Spring – bright red shoots a little like asparagus stems, rapidly growing up to 300mm per week
Summer – large heart shaped leaves, red flecked stems, bamboo like arching stems, dense impenetrable growth – 2m in height
Autumn – white flowers
Winter – loses its leaves leaving brown erect stems
Unfortunately JK has been planted on purpose by the railways companies in the past to stabilise embankments so there are significant areas on railway land that are covered with the plant. If your identification is confirmed I would start by contacting Network Rail and asking them to take action. Network Rail are well aware of the issues surrounding Japanese Knotweed and should be able to give you advice as which treatment they are carrying out, this will typically be a chemical treatment programme.
It is something to be worried about as this could cause issues if you were trying to sell your property. Surveyors are now identifying Japanese Knotweed on land adjacent to property that they are looking at – and insisting that this is dealt with before a sale can proceed.