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3 DIY Methods for killing Japanese knotweed and why they’re terrible ideas 

3 DIY Methods for killing Japanese knotweed and why they’re terrible ideas 

Japanese knotweed being sprayed with herbicide

No surprise here, finding Japanese knotweed can be overwhelming, as it’s an incredibly difficult plant to get rid of.  

We talk to customers every day who decided to try a number of DIY methods to get rid of the Japanese knotweed on their property, before they realise they might have made the problem worse, having lost plenty of time and money in the process. 

Therefore, we thought we’d save you both, by sharing with you the top 3 terrible DIY methods for killing Japanese knotweed, why they won’t work, and what you should do instead to get rid of knotweed for good. 

1. Killing Japanese knotweed with vinegar

Vinegar is amazing. It’s a natural disinfectant, an environmentally friendly way to clean kitchens and bathrooms, and additionally tastes wonderful on freshly bought fish and chips! Looking at many online searches, you might have seen websites promoting vinegar, often mixed with coffee and a garden spray to create an efficient weed killer, due to the acetic acid present in the vinegar.  

Why it’s a bad idea:

Yes, acetic acid can kill plants, yes spraying it on your plant might make its leaves look wilted. However, vinegar isn’t strong enough to stop Japanese knotweed growing new shoots (which could re-emerge at any time), because it won’t remotely harm its extensive, thick, and powerful underground rhizome. 

2. Killing Japanese knotweed with diesel 

Desperate times may call for desperate measures, which might explain why thousands of people attempt to solve their Japanese knotweed problem every year with diesel (spoiler alert: without success!)  

Why it’s a bad idea:

First and foremost, there is no scientific evidence whatsoever that diesel will kill your weed. If you don’t believe in science, believe hundreds of our frustrated clients, who end up seeing regrowth every single time, since diesel will not hurt the plant’s powerful rhizome system.  

To add to that, you’ll also be breaking the law and will most likely have contaminated your soil, making the problem even worse. 

3. Killing Japanese knotweed with bleach 

Household bleach kills many things in and around the home. But what about a growing problem of Japanese knotweed out in the garden? It’s a perplexing question and a remedy many of our clients surely will have tried, but it simply doesn’t get the results they’re after. 

Plenty of people only resort to killing Japanese knotweed with bleach, or trying to, after long and frustrating periods failing to eradicate the plant by other methods. Cutting back the shoots once they start growing will not, unfortunately, do much to arrest the plant’s growth. It will rapidly sprout replacement shoots and keep on trying to take over your garden with its rapid and seemingly unstoppable expansion. 

Why it’s a bad idea:

That’s because killing Japanese knotweed with bleach is not an effective remedy. In fact, it may end up causing more harm than good. For starters, bleach — while excellent for cleaning and disinfecting around the home — is not a weed killer. Bleach is a hazardous chemical that’s not designed for use in the garden. So, simply pouring it over a superweed such as Japanese knotweed may well cause damage to the soil and other plants. Not only that, but the infestation of Japanese knotweed will almost certainly shrug off your efforts and keep on growing. 

Bleach, along with being a poison that may seep into groundwater supplies and harm human health, is best used for killing household germs, not the beast that is Japanese knotweed. What’s required in terms of chemical treatment is a proper herbicide.  

What you should do instead

If you are looking to use chemicals to get rid of Japanese knotweed, your best bet is to use a proper herbicide solution.  

However, without any prior knowledge, you may end up using the wrong chemicals, injure yourself, poison the rest of your plants and even your pets. 

Here’s when professional help, such as Environet will always remain the best option: 

With over 26 years of experience, we will be able to deal with your infestation safely and quickly to avoid any regrowth and ensure Japanese knotweed dies for good. Not to mention the fact that we’ll also be able to provide the all important paperwork that will enable you to sell your house. 

However, it’s important to understand that an effective herbicide treatment will take time.  

If the situation is urgent, you might like to consider an alternative solution, which consists of digging the Japanese knotweed to get rid of its problematic root system and eliminate it in a matter of days. 

Find out more about our removal solutions here.

Robert Spaceman

“We had a large stand of bamboo removed, thinned, contained and replaced. The customer service has been first class. Joe and Jason were fabulous and kept me well informed at all times”.