Discover the best weed killer to kill Japanese knotweed and rid your property of this invasive menace. Japanese knotweed can have disastrous consequences to property, the environment, and the structural integrity of buildings if one does not get rid of it at the earliest possible stage.

The tenacious root system of this highly invasive weed plant can cause havoc even to the strongest of structures thus, calling for the need to have the whole weed plant exterminated. To this end the best ways to kill Japanese knotweed are:

Using weed killer to kill Japanese knotweed

Weed killers are chemical components that are designed to eradicate invasive weed plants whenever they infest a certain area.  

Any weed killer for Japanese knotweed has a non-restrictive use meaning you can readily make use of such herbicides even on your private property based on the fact that they do not carry along serious restrictions as regards their usage.

Generally, weed killers that contain glyphosate are deemed to be the most effective when it comes to the eradication of Japanese knotweed; an example of such a weed killer is “Round-Up” which has numerous success stories on its effectiveness.

Professional weed killer to kill Japanese knotweed
Professional weed killer to kill Japanese knotweed

Procedure for Using Weed Killer to kill Japanese Knotweed

Experts across the board maintain a consensus that for any weed killer to work perfectly, the large stems/canes of the weed plant must be the first cut down.

By reducing the weed plant to smaller pieces you are increasing the levels of efficiency of the weed killer. Large uncut stems will take longer to destroy as compared to smaller ones.  The process is as elaborated below:

  1. The first course of action before the application of the weed killer is to cut down the canes of the Japanese knotweed.
  2. Clear the cut canes from the infested area. If this is not possible you can choose to leave them on the infested site but make sure you spray them with the weed killer and burn or bury them appropriately.
  3. Read and understand the manufacturer’s guidelines regarding the usage of the particular weed killer for Japanese knotweed. Do not assume that each weed killer is to be applied in the same manner.
  4. Ensure that you have mixed the recommended dosage before application. Do not put too much-measured quantity thinking that it will work faster or less amount because you will only get limited results.  
  5. Ensure that you do not use herbicides near water bodies or public water drainage systems as this may lead to contamination.
  6.  Always allow a minimum of at least 7 days before pulling out the dead remains of the Japanese knotweed from the ground.
  7. Constantly check on any new infestation, if any, because at times some rhizomes may still survive the first process of the herbicide treatment.

The usage of herbicide treatment as a weed killer for Japanese knotweed has been hailed as the most effective approach to getting rid of this invasive weed plant, provided that, one follows all the recommended guidelines from the manufacturer on the proper usage of each weed killer.

Japanese knotweed treatment via spraying glysophate chemicals
Kill Japanese knotweed with the treatment by spraying Glysophate chemicals

Burning of the Japanese knotweed 

Burning, in this instance, requires the use of a micro-incinerator so that no rhizome of the weed plant survives the burning.  Importantly, for burning to be effective, you must ensure that the pieces of weed plants are completely dried and devoid of moisture.

Burning must also be done in a closed area to avoid emissions and the possibility of remnants of the weed plant being blown away.

In instances where the quantity of the weed plant to be burned is large scale such that the fire to be used will be of equivalent size, it is prudent to consult with the authorities to put in place safety measures to avoid a greater disaster.  

Once you have successfully burned the remains of the Japanese knotweed, you must dispose of them as a precautionary measure.

The burnt waste product must be packed in closed containers or plastic carriers to avoid any spillage while in transit to a landfill site that is authorized to deal with such waste material.

As a precautionary measure, it is not advisable to bury the remains in your land for the reason that if there was a piece of the weed plant that was not killed by burning, its growth can be avoided within the same area that has been cleared of the weed plant.

If carried out by the rules of the book, burning stands as one of the best methods to get rid of Japanese knotweed.

Burning is a short term solution to kill Japanese knotweed
Burning is a short-term solution to kill Japanese knotweed

Digging up the roots of Japanese knotweed

Japanese knotweed root system is quite tenacious and, intrinsically, responsible for the rapid spread of this highly invasive weed plant. The roots themselves are a menace as they can grow 3 meters deep into the soil and approximately 7 meters wide in any direction.

They can rip through weakened concrete or wall spaces; hence, taking out such roots is essentially a step forward towards eradicating the weed plant for good.

The roots can be dug out either using home-based tools such as a shovel (where the roots are relatively undeveloped) or the use of special machines (excavators), preferably in instances where the roots are fully developed and deeply ingrained in the soil.

The latter option is rather costly as compared to using home-based tools because one may need to hire special machines. Equally, due to the heavy nature of excavators, this may result in significant destruction of the garden/property in which the digging out of the roots is to be done.

This means that extra costs to repair and restore the land may be incurred.  

Taking into account that machines may fall short when it comes to accuracy during the digging, it is possible to find that small fragments of the weed plant have been left on the ground, therefore, even after the machines are through, one may be forced to go around doing a physical check-up and personally take out any left fragments on the ground.

Nonetheless, if excavation is done prudently and in a professional manner, it is one of the best methods to get rid of Japanese knotweed for good from your property.

Want to know more about finding the best weed killer to kill Japanese knotweed?

Knotweed Removal aims to provide the most up-to-date information, help, and advice for YOU to make informed decisions. If you are unsure or uncertain about how to proceed, please reach out to us and we will gladly come back and advise you as best we can.

Governmental advice can be found here and the UK law covering the removal of Japanese Knotweed as stated under the Wildlife and Countryside Act 1981 can be found here.

The best means to contact us is via our email –

Do not forget we have a library of blogs covering many areas relevant to Japanese Knotweed, our free downloadable How-to Guides and Product Reviews on the latest methods being employed to eradicate or remove Japanese Knotweed.

Knotweed Removal, UK

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Rootblast | Super Strength Concentrated Total Weed Killer - Glyphosate for Effective Weed Control - Kills Weeds down to the their roots (1 x 1L)
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Roundup Fast Action Weedkiller Pump 'N Go Ready To Use Spray, 5 Litre
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  • Degraded in the soil by micro organisms
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