There is a multiplicity of methods on how to find the best way to kill Japanese knotweed with each having different results based on its application.  As soon as you spot this weed plant growing near your property, you should act fast and figure out the most effective way to eliminate it completely.

For instance, the use of weed killer for Japanese knotweed is one of the most effective methods to get rid of this invasive weed plant weed.

A multiplicity of other methods exist hence it is encouraged that only the tried, tested, and approved methods of permanently removing Japanese knotweed are put into use to get rid of the weed once and for all.  

On this footing, the following segment will dwell on some of the best approaches to killing Japanese knotweed albeit not in their priority order; notably, experts across the board agree that for one to get the best results, it is advisable that each method is used alongside another.

Best way to kill Japanese knotweed permanently so you stop the spread of this invasive weed
Best way to kill Japanese knotweed permanently so you stop the spread of this invasive weed

The methods are as explained below:

Using herbicides/weed killers for Japanese knotweed

Herbicides are basically chemical elements that are industrially manufactured and meant to deal with various weeds in their various forms.

The tested tried and proven herbicides that have been deemed to work with effective results are the ones that contain Glyphosate in them an example being the “Roundup Tree Stump” herbicide for the Japanese knotweed.

Herbicides can be very harsh to the environment; hence because of the high chemical compounds in them, thus when using them, it is only right one ensures they are familiar with the procedure of applying them to the weed plants.

In passing, chemicals are effective if applied directly to the weed plant or the liquid is directly injected into the stems of the weed plants to allow for decomposition from inside out.

As a precautionary measure, always ensure that you read the instructions manual of each chemical before usage. Chemicals can be quite lethal to the surrounding environment and even the human body; hence taking extra caution should be paramount.

Often, for chemicals to offer the best results, experts advise that they can either be sprayed directly into the weed plants (after cutting down the canes) or, in some instances, by injecting the chemical into the stems of the weed plant.

Japanese knotweed treatment via spraying glysophate chemicals
Best way to kill Japanese knotweed with treatment via spraying Glysophate chemicals

Cutting and digging the root out.

Bearing in mind that the Japanese knotweed can grow to heights of 7 feet (2.1 m), it has quite long canes that should be cut down easily.

However, this removal DIY method requires one to be very precise by trimming the canes as close to the ground as possible and getting to the root to prevent the Japanese knotweed from re-growth hence eradicating them. 

Further, it is important to ensure that the cut canes are taken far away from the garden to prevent them from growing again.

In some instances, where the root system of the Japanese knotweed is deeply ingrained in the soil such that after cutting it, a potential re-growth is likely to occur, you can consider using excavators to get rid of the weed plant completely from the soil.

Burning or Burying the Japanese knotweed

Burning Japanese knotweed requires the use of a micro-incinerator for the process to be successful. The aim of this exercise is to subject the Japanese knotweed to very hot temperatures to guarantee that no rhizome survives the process.

This is why it is always advisable that before subjecting the weed plant to incineration, you let it dry completely such that it is destitute of moisture completely.

Most importantly, considering that Japanese knotweed is a “controlled waste” this obligates one to follow certain measures when disposing of the waste product even after burning.

Notably, disposal is supposed to be at a landfill site that is authorized to receive such waste products and securely have them disposed of. If you choose to personally have the waste transported to the landfill site, then you must ensure the carrier containers or bags are sealable.

Otherwise, it is advisable that you seek professional services to do the job. Consequently, if the burning of the weed plant is done adeptly and, all the right steps are followed, then it makes the cut is a permanent Japanese knotweed removal method.

Burying, in contrast, does not necessarily require that the weed plant is burned before being disposed of, albeit, it is better if you consider burning the waste.

The most important thing to remember when burying Japanese knotweed is that the remains must never be mixed with domestic waste because this can aid in the potential re-growth of the weed plant.

Additionally, experts recommend that after cutting or digging out the Japanese knotweed, you give it time to decay then bury the waste using bags that are completely sealable.

Once the above-mentioned measures of burying the weed plant are followed to the latter, permanent Japanese knotweed removal will be attained.

Stockpile and treatment of rhizomes in a metal container prior to removal
Best way to kill Japanese knotweed with the treatment of rhizomes in a metal container prior to removal

Use of membrane barriers

One may wonder how to kill Japanese knotweed using membrane barriers but this method has proved to work if put to proper use. Preferably, barriers should be used either when the cutting of the invasive weed plant has taken place or when the plant is at its early level of growth.

Just like any other plant, the Japanese knotweed heavily requires enough sunlight and water for growth; therefore, denying it such luxury impedes its rapid growth.

The membrane barriers should be positioned on the soil surface leaving the weed plant underneath it deprived of sunlight. Heavy objects should be put on top of the membrane to avoid them from being blown away.

Membranes should also be placed on the periphery areas of the land to avoid rhizomes escaping sideways in search of precious sunlight for their growth.

Burying Japanese knotweed underneath an impervious membrane
The best way to kill Japanese knotweed is by burying Japanese knotweed underneath an impervious membrane

In conclusion

The above-mentioned methods are not cast in stone because as the world evolves, there are always new, fresh and better ideas on how to solve any problematic matter within society.

There are various success stories on how to completely eradicate this weed plant that one can borrow inspiration from. However, it is always important to ensure that the method you chose is one that will give you the desired results.

Bestseller No. 1
Bayer Garden 2 x Path, Patio & Drive Weed Killer & Watering Can Set - 3 x 8g Sachets per pack treats upto 75sqm - Kills Ground Elder, Nettles, Docks, Couch Grass & Japanese Knotweed.
  • This exclusive twin pack and 9L Watering Set is everything you need for clearing weeds from paths, patios and rives including areas of tarmac, concrete and block paving.
  • Kills tough weeds and their roots including: Ground Elder, Nettles, Docks, Couch Grass, Japanese Knotweed, Brambles, Bracken & Ivy.
  • Each box contains 3 x 8g Simple ready measured soluble doses and treats up to 75sqm. Apply at any time when weeds are showing green leaf and are actively growing.
  • Sold with our durable 9L or 2 gallon capacity galvanised steel watering can with removable brass rose. Colour cannot be guaranteed. Watering can will be randomly picked and despatched.
  • Keep children and pets away from treated areas until the spray has dried.
Bestseller No. 2
Roundup Tree Stump Weedkiller, Super Concentrate 250 ml
  • Kills ivy japanese knotweed, saplings, brambles and nettles to the root
  • Kills up to 16 tree stumps
  • Contains a reusable pipette for specialist treatment of japanese knotweed
  • Kills the roots so weeds don't come back
  • Degraded in the soil by micro organisms
SaleBestseller No. 3
Weedol 011005 Pathclear Weedkiller Liquid Concentrate, 6 + 2 Tubes
  • Unique dual action fomulation, kills weeds to the root and prevents new weeds growing for up to 3 months
  • Ideal for paths, drives and patios
  • No measuring or mess - just add water
  • Creates an invisible barrier that prevents new weeds for up to 3 months
  • Children and pets need not be excluded from treated areas (once dry)
Bestseller No. 4
RootBlast - RootBlast 360 Glyphosate Home Garden Weedkiller - 1L Bottle with Integral Measuring Device Pair - Includes Pair Of gloves - 1L Makes Up to 50L
  • WEED KILLER CONCENTRATE: Rootblast's strong weed killer is both super-concentrated and tough on most broad leaf and grass weeds. It's specifically designed to bring you the best results by using systematic herbicide technology. It targets weeds from the inside and kills them at their underlying roots, preventing any future growth
  • GLYPHOSATE WEED KILLER: For optimal weed control, Rootblast have created a concentrate weed killer that contains 360g/l of glyphosate. Glyphosate is a broad-spectrum systemic herbicide and crop desiccant that is used by famers. It kills and destroys the weed without affecting the crop. By using glyphosate, Rootblast's weed killer is stronger and more effective than most other weed killers on the market
  • GLYPHOSATE HERBICIDE: This powerful and effective weed killer is designed to target weeds such as dandelion, grasses, docks, nettles, willowherb, bindweed, woody brambles, tree stumps, ivy and more. After applying Rootblast's heavy duty weed killer, the first signs of weed control are visible when the weed leaves yellow - this can take anywhere from a few days to up to 2-4 weeks. From this 1 litre bottle of glyphosate herbicide concentrate, you can make up 50 litres of product when it's diluted
  • DOCK, GRASS & DANDELION KILLER: Alongside this industrial strength weed killer, you'll receive a pair of protective gloves as well as the integral measuring device attached to the bottle. The gloves provide you with protection to ensure your experience is as easy and safe as possible. The integral measuring device is an inbuilt measuring cup, simply remove cap and carefully squeeze the container until the cup is full
  • TOTAL PROTECT WEED GARDEN SPRAY: This easy to use product is available as a ready to use tough, concentrated weed killer that comes with a integral measuring device attached and protective gloves. Use by professional garden and farmers, this product can tackle your weed problem and kill the weed from the root - the ultimate weed killer!
Bestseller No. 5
Rootblast Glyphosate Weedkiller 4 x 100ml Concentrate with 5L Pump Sprayer
  • For use on unwanted vegetation and areas not intended to bear vegetation
  • Contains 72 g/l glyphosate for effective control of annual and deep-rooted perennial garden weeds, including grasses*, docks, nettles, willowherb, dandelion and bindweed. Also suitable for woody brambles, tree stumps and Ivy.
  • Coverage up to 66sqm per sachet

Want to know more about the best way 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.

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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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