The period of getting rid of Japanese knotweed cannot be fixed or accurately predicted because this factor is pegged on a number of aspects such as the methods one chooses to use and the tenacity one has towards eradicating this invasive weed plant.

Certainly, there is no quick-fix remedy to completely eradicate this unrelenting weed plant; however, all hope is not lost since most approaches have very effective results over time. 

Notably, experts across the board agree that in order to have the shortest eradication time of the weed plant, using multiple approaches at a go may prove to work best based on the fact that the versatility and tough nature of this highly invasive weed plant not forgetting its ability to grow in various environments makes it a menace.

On this footing, the aspects that greatly influence the time it will take to get rid of the Japanese knotweed are as follows:

Development stage

Evidently, Japanese knotweed which is at its early stages of development is easier to get rid of as compared to when it is fully developed. The canes and roots of the younger plant are fragile and can be taken down with no trouble.

However, with each stage of growth, the weed plant gets bigger and stronger such that you will require more effort and resources to eradicate the weed plant.

Notable, the roots of the mature weed can grow up to 3 metres deep and 7 metres wide in any direction. What this implies is that the earlier you deal with the Japanese knotweed, especially, when it is quite undeveloped, the better chances you stand of killing it immediately.

Getting rid of Japanese Knotweed should be a priority if it encroaches from a neighbouring property
Getting rid of Japanese Knotweed should be a priority if it encroaches from a neighbouring property

Scope of the infestation

Significantly, in places where the Japanese knotweed has rapidly spread such that it is growing in large-scale quantities, essentially, this implies that getting rid of the weed plant will take a longer time as compared to an infestation that is minimal.

Large-scale properties facing an attack from the Japanese knotweed will seemingly, require putting together more resources and manpower to fight the Japanese knotweed and hence, this may take quite a while to guarantee full eradication.

On the other hand, small properties can apply removal DIY methods effectively and get rid of Japanese knotweed within a very short time span.


To completely get rid of Japanese knotweed, however small the infestation you need to set aside human and financial resources to get the job done.

In particular, if you are facing a bigger threat of the Japanese knotweed infestation, this calls for more resources to be availed to effectively tackle the weed plant. For removal DIY methods, you will require sufficient human manpower.

Additionally, it is important to note that the extent of resources required depends on the method of eradication one chooses to use and substantially on the scope of the infestation.

Mental strength

Getting rid of Japanese knotweed is not a walk in the park. You must be dedicated and have the proper mental willpower to get you across the line. This weed can be persistent and annoying if not taken down within a short time span.

If you do a half-hearted job, then you will have a bigger problem to deal with because the re-growth of the weed plant does not stop just by mere cutting or trimming of the canes.

Specialised services

A large-scale infestation of the Japanese knotweed will require that you seek specialized services from persons that are well-refined in the area.

Professionals will help you understand the cost aspect involved to get rid of the Japanese knotweed, the treatment plan that will suit your particular case scenario and most importantly the connections that will help you in eradicating the weed plant.

Notwithstanding the above factors, different approaches take different time frames to effectively get rid of Japanese knotweed. To better understand this occurrence, the following section will look into this with more details based on the most common methods:

Aim to get rid of Japanese Knotweed before it spreads and becomes a larger problem on your property and potentially that of your neighbour
Aim to get rid of Japanese Knotweed before it spreads and becomes a larger problem on your property and potentially that of your neighbour


Physical methods are those to do with actual human effort and skills to get rid of the Japanese knotweed.

The most common physical methods used to kill Japanese knotweed include; digging out the root system of the weed plant, covering it with barrier membranes, burning and burying, smothering and mowing the weed plant.

The following segment will reflect which of these methods will take a shorter time and those which will take a longer time to get rid of Japanese knotweed:

Short-term oriented

Digging out the root system and burning the Japanese knotweed approaches have almost an instantaneous effect as the life of the weed plant is killed immediately. Taking the roots out of the soil denies the plant moisture and the rich soil components to facilitate growth.

This essentially means that after the weed plant has dried up and been disposed of properly, its growth is stopped within a short period of time. Burning on the other hand has the same effect of bringing an abrupt end to the life of the Japanese knotweed plant.

Therefore, these two methods can be said to have a quick effect on getting rid of Japanese knotweed if applied appropriately.

Long-term oriented

The use of barrier membranes, smothering and mowing of the Japanese knotweed physical approaches do not have a fixed time frame in which one can say that complete eradication has taken place as a result of their application.

The reason for this is that these methods lean on the control aspect of the Japanese knotweed rather than the full eradication of it.

This is not to say that they cannot be used to get rid of the Japanese knotweed but one would have to wait for an unprecedented time frame to determine whether the applied method has worked and eradicated the weed plant in totality.


Herbicides have a non-restrictive use hence; anyone can readily buy and use them to eradicate the weed plant.

Although not cast in stone, where the weed plant has infested a smaller space, once you apply the herbicide, it is always advised that you must wait for at least 7 days to give the chemical time to work on destroying the weed plant.

If this period passes and you still note the presence of the Japanese knotweed on your property, you can re-apply the chemical to the unaffected weed plants until you get the desired results (eradication).

In instances where you choose to hire professional firms that specialize in the removal of the Japanese knotweed mainly because the infestation is large scale companies will give you a working insurance policy of 3 to 5 years which will act as their guarantee to get rid of the Japanese knotweed from your property within the stipulated period.

Such a policy does not, however, imply that it will take up to 5 years for the weed plant to be eradicated; it is just a precautionary grace period just in case there is a new infestation within that period even after subjecting the weed plants to the chemical treatment. This is due to Japanese knotweed typically taking longer to remove completely.

Therefore, depending on the size of the infestation, when you apply chemicals to Japanese knotweed, it can take a period ranging from 2 weeks to 5 years or longer depending on the scale of infestation.

Aim to get rid of Japanese Knotweed before it spreads and becomes a larger problem on your property and potentially that of your neighbour
Aim to get rid of Japanese Knotweed before it spreads and becomes a larger problem on your property and potentially that of your neighbour
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 how to get rid of 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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