How to Kill Japanese Knotweed

ByKyle Marsh

How to Kill Japanese Knotweed

Many people believe it is impossible to know how to kill Japanese knotweed due to incorrect and miss leading information they have read on the internet!

They may type into a search engine how to kill Japanese knotweed and find that you cannot kill the plant and that it will ruin the chances of you selling your property. You are told that the buyer of your property will have to be a cash buyer, with the potential that you will have to accept an offer 30% below the market value. In nearly all cases this is totally untrue. As long as the correct procedures are followed, in most, cases there should be no reason why your purchaser cannot obtain a mortgage on your property.

The three things you require to satisfy the buyer’s mortgage company are a detailed survey, a Management plan, and sometimes a 10-year insurance backed guarantee may be required.

Admittedly Japanese Knotweed is not an easy plant to control, to remove or kill it can take many, many, years depending on the age of the plant. Japanese Knotweed spreads wildly and can become out of control if it is not treated.

This plant is used to growing on the sides of volcanos in Asia in volcanic soils with high porosity, low pH, and high moisture retention. These are things this plant likes. Europe is a great place for this plant to live because here it has no natural predators. Back home there are small weevils, these insects know how to kill Japanese knotweed and will eat the plant keeping under control.

Underground, Japanese knotweed spreads its rhizomes making this plant harder to reach.

The Rhizomes can be as deep as two meters and spread out from the crown as far as 7meters in all directions.

You may ask yourself How do I kill Japanese knotweed? Naïvely people tend to pull, cut and mow it down hoping that they will not see it again. Unfortunately, this doesn’t eradicate the problem. If you wish to kill Japanese knotweed you require a herbicide spray or stem injection. There is also an option to dig out the Japanese knotweed, however, you must make sure all the Rhizomes are removed. If not the Japanese knotweed will just start to grow again from the tiny fragments left in the ground. The environment agency prefers the Japanese knotweed is herbicide treated as this minimises the risk of spread from the site.

Look for professionals, like us to kill the Japanese knotweed, this will save you time and money. Throughout the growing season, we will repeat the process of spraying the Japanese knotweed to ensure no more growth is reoccurring.

Here is what NOT to do if you want to kill Japanese knotweed;

  • Do not cut/strim/mow it down
  • Do not dump waste soil from around the Japanese knotweed in the garden waste, this will cause Japanese knotweed to grow again.
  • Never put any part of the plant into your dustbins or skips, you could face a large fine from the environment agency if you get caught.
  • Remember it is an offence to let Japanese knotweed grow in the wild.

If you have Japanese Knotweed in your garden you could face prosecution if you allow it to spread into a neighbouring property.

When we take on a Japanese knotweed treatment, we are extremely careful we do not contaminate surrounding areas with Japanese knotweed waste.

Never improvise or treat the Japanese knotweed yourself. Do not put petrol, diesel or weed killer on the plant as this could make the plant seem as if it has been killed. When in fact the plant has lapsed into dormancy, this means potentially it may not send any more shoots up for up to ten years.

If there are no shoots this means the plant cannot be treated

Depending on the age of the plant and its location It can take several years to kill Japanese knotweed however if you are patient and follow correct procedures it can be eradicated.

The best time to kill Japanese knotweed is in late summer around September while the plant is flowering. At this time, the knotweed will also be at its highest, it can reach up to 3 meters in height.

During different seasonings Japanese Knotweed changings, from blossoming Milky cream small flowers in late summer to just brown hollow canes in the winter. However, don’t be mistaken that your Japanese knotweed has shrivelled up and died, although it may look dead it most certainly isn’t. The plant is extremely healthy and is hibernating underground waiting to send up brand new shoots when the warmer weather returns in the spring.

It’s worth mentioning that in the UK it is illegal to put any part of Japanese Knotweed into bins or skips. If you are caught putting any part of the plant into normal waste there can be serious consequences including heavy fines.

After you have received your detailed survey that will include our recommended treatment plan on how to kill Japanese knotweed. You will be able to make a decision on whether you would like to go on with treatment.

If you decided to go ahead with the treatment you will receive a management plan, this will tell you how we intend to treat the Japanese knotweed. There are plenty of stories where people have struggled getting mortgages and losing a lot of value to their house due to having Japanese Knotweed.

Issues to consider

Lenders/banks will want a valuation of your property before they agree to lend you the mortgage, if Japanese knotweed is found on your land this will raise a concern. Until your property is cleared of Japanese knotweed the value of your house may be affected. There have been stories of people losing thousands on the value of their houses. If you take no action and the Japanese knotweed spreads and gets bigger you are responsible and can be prosecuted. A quick call to us for reassurance will save you a lot of hassle. We guarantee you a hassle-free way to kill the Japanese knotweed once and for all.

About the author

Kyle Marsh administrator