What is Japanese Knotwood & How can it Affect me?

What is Japanese Knotwood

Japanese knotwood also known as Fallopia japonica is a tall fast-growing Japanese plant of the dock family. It features long bamboo-like stems, small lacy clusters of white flowers & pointed leaf tips. It was brought to the UK as an ornamental flower however, it has quickly become a big problem for home-owners.In the words of the Environmental agency, Japanese knotwood is:

Indisputably the UK's most aggressive, destructive and invasive plant

But why is it such a threat? We look at some of the reasons below.

Japanese knotwood can grow 3-4 meters in as little as 10 weeks which is the equivalent of 2 grown adults!

Its roots or rhizomes can spread 7 meters horizontally and can potentially compromise the structure of buildings.

If evidence of Japanese knotwood is found by a banks valuer or it has been a known problem in surrounding areas, a specialist survey will have to take place. This can put off lenders to the point where they wont lend at all.

In the right temperatures and surroundings, it can grow up to 20cm everyday!

It can even grow through concrete and tarmac and its roots can go down up to 3 meters deep.

There are currently no natural predators in the UK to combat it meaning it can grow without interruption swamping other plants and preventing them from growing.

Although it does not produce seeds, Japanese knotwood can grow from small fragments of rhizomes allowing it to spread veryquickly & easily.

Knotweed costs the UK economy 166 million per year for treatment and in home devaluations.

What does it look like?

Below is a picture showing what Japanese knotwood looks like during the different seasons.

What can I do about it?

1. Dig it all outYou can dig out Japanese knotwood but if even a small piece of its root is left behind it can grow again into a new plant.Also note that Japanese knotweed is classified as controlled waste so if you do dig it up, you can only dispose of it at licensed landfill sites.

2. Kill it with chemicalsYou can use chemicals to get rid of it. Treatments containing glyphosate will work but it can take up to five years treatment to get rid of the weed completely.

3. Eat itYes you can eat it but youd need to eat a lot to get rid of it completely!