Weed killers, chemicals and excavation methods explained by the specialists.
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What works
The most effective over-the-counter herbicides are glyphosate-based weed killers such as:
- Roundup
- Gallup
- Landmaster
- Rodeo
- Touchdown
These are known as translocated herbicides, which means they are absorbed by the leaves and carried down into the roots. This is essential when treating knotweed, as surface treatments alone will not reach the underground rhizomes.
For best results:
- Apply in late summer or early autumn, when the plant naturally draws nutrients into its roots
- Repeat applications annually over at least three to four growing seasons
- Apply to healthy, leafy growth, not recently cut stems
What doesn’t work
Many DIY products fail because they are contact-only weed killers, which damage only the visible parts of the plant. These can make it seem like the problem is solved while the root system continues to thrive underground.
And despite what you might read online:
- Bleach, vinegar, and salt do not kill Japanese knotweed
- These substances may damage your soil and garden but will not prevent regrowth

Stop trying to kill Japanese Knotweed yourself!
We can help provide a solution that lasts.


Stop trying to kill Japanese knotweed yourself!
Did you know knotweed can regrow with only a thumbnail’s worth (around 0.2g) of its root system left in the soil?
We can help provide a solution that lasts.

Common Japanese Knotweed Killing Misconceptions
Can you kill Japanese knotweed with bleach?
No, you cannot kill Japanese knotweed with bleach. All it will do is cause more damage to your garden and the environment surrounding its application. We would not recommend wasting your time using this household product to try and treat your knotweed problem, even if it has some effect on its growth – it will not be sufficient in any way.
Can you kill Japanese knotweed with vinegar?
No, there is no hard evidence that vinegar is successful at killing Japanese knotweed, and like bleach, we would not recommend wasting your time using this condiment on your knotweed problem.
Can you cut back Japanese knotweed?
Despite websites like Wikihow claiming that Japanese knotweed will not regrow from cut canes, cutting back knotweed alone will not do anything and will not kill it. It will grow back – take it from the experts.
Other Viable Options for Killing Japanese Knotweed
Stem injections
In more environmentally sensitive areas (when you do not wish to damage neighbouring plants), there is also the option for stem injections of the weed killer instead of spraying it. This treatment method is often chosen on residential projects due to the precise nature of the application.
Digging Up The Knotweed
There are also cases where a more immediate strategy is required. In these instances, the best option is to dig up the Japanese knotweed. By digging up the infected area, it’s ensured that any trace of Japanese knotweed is gone. This is essential since even the tiniest fragment of rhizome left in the soil can regrow. This is the only available technique if the land in question is to be used for future development purposes.


Risks of Failing to Kill Japanese Knotweed
From costly fines to damaging pipework, failing to kill Japanese knotweed fully can lead to multiple problems when not managed:
- Costly fines – if you allow Japanese knotweed to spread to neighbouring land, you could land yourself a £5,000 fine
- Difficulty getting a mortgage – additional steps may be needed when buying or selling with Japanese knotweed present, and may even be refused dependent upon the lender.
- Risk of subsidence – if your property has weak spots, you may be at risk of subsidence where Japanese knotweed roots create ground movement.
- Damage pipework and buildings – Japanese knotweed’s deep roots take hold underground, and can even penetrate through foundations and pipework.
Important Information Regarding Knotweed Disposal
When it comes to the digging up and disposal of Japanese knotweed, a licensed waste carrier, such as Japanese Knotweed Specialists, must be used as knotweed is a controlled substance.
Alternatives to Digging Up Japanese Knotweed
Root barriers to prevent spreading
Used purely as a means of halting the spread of Japanese knotweed, the installation of a root barrier is an option. This impenetrable barrier goes down three metres (Japanese knotweed roots go down just over two) and therefore stops the plant spreading into any neighbouring lands. The Japanese knotweed root system (rhizome) cannot grow through the root barrier and thus the infestation is completely contained.
Contact a professional Japanese Knotweed Specialist
Tackling Japanese knotweed is a difficult process and can take a long time to complete. We normally suggest about two years – four whole growing seasons to be sure. Some people take it on themselves to remove this troublesome plant, but the problem is that even a 0.2g fragment of Japanese knotweed rhizome can regrow – leaving you back where you were at the start.
The best way to ensure a complete, thorough and lasting extermination is to contact a professional Japanese knotweed removal company like Japanese Knotweed Specialists.

Frequently Asked Questions
Can I kill Japanese knotweed myself?
You can try, but complete eradication is unlikely without professional help. Over-the-counter herbicides require multiple years of repeated application, and even a small fragment of root left in the ground can cause regrowth. For long-term control, most people eventually turn to specialists.
What is the best time of year to kill Japanese knotweed?
Late summer to early autumn is the most effective time to treat knotweed. This is when the plant is moving energy into its roots for winter, which allows herbicide treatments to penetrate deeper into the rhizome system.
Will Japanese knotweed die in winter?
The visible parts of the plant may die back, but the underground rhizomes remain alive and dormant. Knotweed often regrows in spring unless the roots have been fully killed or removed.
How long does it take to kill Japanese knotweed?
Using domestic herbicides, it typically takes at least three to four growing seasons to fully kill the plant. With professional-grade treatments or excavation, the process can be much quicker.
Does vinegar, salt or bleach work on Japanese knotweed?
No. These household substances may burn the leaves but won’t reach the root system. They also risk damaging your soil and nearby plants. Glyphosate-based weed killers remain the most reliable chemical option.
Is it illegal to have Japanese knotweed on my property?
It’s not illegal to have knotweed on your land, but you are legally responsible for preventing it from spreading to neighbouring properties. In some cases, this can lead to fines or legal action. Learn more about your responsibilities under UK knotweed law.
Can you just cut down Japanese knotweed to get rid of it?
Cutting back knotweed without follow-up treatment will not kill it. The plant will continue to grow from the underground roots. In some cases, cutting can even stimulate further spread.
Get Rid Of Japanese Knotweed Today
Speak to one of our specialists now on 0800 122 3326 or fill in our contact form by following the link below.
