How to get rid of Japanese knotweed via spraying chemicals

Getting rid of Japanese knotweed is not easy due to its invasive nature but with time and patience, it is possible. If you have identified Japanese knotweed in your garden and want to get rid of it, here is what you need to know in order to know how to get rid of Japanese knotweed permanently.

Why do I need to get rid of Japanese knotweed?

If you have Japanese knotweed in your garden, you will probably want to control its growth and spread so that it does not either damage your property or spread into areas that you do not own.

If the plant spreads from your property into the wild, then that is illegal according to the Wildlife and Countryside Act 1981. If the plant spreads onto someone else’s property or public land and you do not actively work to control its spread, you could be subject to legal action which could result in an ASBO and be fined.

How to get rid of Japanese knotweed via spraying in a garden

How to get rid of Japanese knotweed

There are a number of ways to tackle Japanese knotweed. Here we list three of the most popular options:

Digging it up

This can work, but because the root systems are so extensive (up to 22ft) and because the plant spreads by rhizomes (the extensive network of underground shoots). This is not an ideal solution as regrowth will often occur.

If you do choose this method, there are some important things to consider. Any waste you have which contains Japanese knotweed must be disposed of properly. It can only be removed to a landfill site that has an appropriate permit.

Furthermore, it can only be taken to the landfill by a specialised registered carrier, whose vehicle must be thoroughly cleaned after use. Most landfill sites will refuse you offloading it here. This also applies to skips, which again do not accept Japanese Knotweed.

You should never compost waste containing Japanese knotweed because it can survive the composting process and it must never be disposed of with the normal household waste as it is a contaminant. If the council identify you as the source they will prosecute you.

Taking measures to the extreme you could undertake professional excavation which is both costly and invasive, depending on your site. This is by far the quickest solution but one that is not available to most homeowners due to the scale of work required.

Burning it

Controlled burning is the best and safest way to get rid of Japanese Knotweed. Private householders can burn Japanese knotweed waste under controlled conditions in the garden.

It is possible to burn the Japanese knotweed waste on your land after letting it dry out first, but Japanese knotweed rhizomes may still survive the burning process.

However, you cannot transport the waste to another site to burn it or take the burnt waste to your council’s standard landfill, or recycling centre as this will introduce cross-contamination. It will require a licenced professional and permission to take it to the specialist landfill site for removal.

How to get rid of Japanese knotweed by burning it to ash
How to get rid of Japanese knotweed by burning it to ash

Chemical treatment

Many people oppose using chemicals to treat weeds and plants in the garden. However, with a plant as tenacious as Japanese knotweed, it is the safest, most recommended option.

Use only approved weed-killer or root-killer chemicals in accordance with the manufacturer’s instructions to ensure the safe eradication of the weed.

Herbicides, including Glyphosate-based products, are effective at eradicating this notorious plant. Glyphosate-based herbicides are applied to the foliage of the weed using a sprayer after being mixed in a tank. The Glyphosate herbicide can also be injected into the stem. This method is most suitable for ecologically sensitive areas where spraying is not suitable.

It’s advisable to spray the Japanese knotweed through various stages of the plant’s development during the growing season. The infestation size, presence of watercourses and the general public all have to be considered during herbicide selection.

The Royal Horticultural Society recommends using a glyphosate-based weed-killer to tackle Japanese knotweed, particularly Scotts Roundup Tree Stump and Root Killer.

When applying chemicals to Japanese knotweed always cut back the plant stems before applying and remember that it will need to be repeated regularly as it can take three to five years to fully treat Japanese knotweed, so plants will have to be resprayed every year.

Try to avoid any other plants when you spray and the best way to do this would be via injecting the knotweed rather than spraying.

How to get rid of Japanese knotweed by spraying
How to get rid of Japanese knotweed by spraying

Professional help to remove Japanese Knotweed

Japanese knotweed can be quite difficult to remove, so don’t get discouraged if your attempts fail to eradicate it completely.

There are many companies offering their services to dispose of Japanese knotweed. Check out the British Association of Landscape Industries website, as recommended by the Royal Horticultural Society, for a list of its members who treat invasive species.

Japanese knotweed is a perennial non-native plant from the knotweed family which is subject to certain Government legislation due to the speed and spread of its growth choking other plants in its path.

If you have identified Japanese knotweed in your garden and want to get rid of it, employing the services of a professional in Japanese knotweed removal will ensure it is done correctly and in line with a treatment plan that will not affect your other plants within your property.


Want to know more?

How to get rid of Japanese Knotweed Permanently

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 – hello@knotweedremoval.tips

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

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
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. 3
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
Bestseller No. 4
Bayer Garden 2 x Path, Patio & Drive Weed Killer - 3 x 8g Sachets per pack treats upto 75sqm - Kills Ground Elder, Nettles, Docks, Couch Grass & Japanese Knotweed.
  • Ideal 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.
  • Keep children and pets away from treated areas until the spray has dried.
Bestseller No. 5
Tree Stump Killer Root Killer Prfessional Roundup Tree Stump & Root Killer 250ml
  • Roundup Tree Stump Weed Killer 250ml Tree Stump & Root Killer Up To 16 Stumps
  • Kills stumps, trees, brambles, nettles, deep rooted and woody weeds.
  • Kills Tough Weeds to the roots.
  • Kills up to 16 Stumps
  • Roundup stump killer is a non-selective, translocated weedkiller that is absorbed by leaves and freshly cut, woody surfaces and moves throughout the entire plant, above and below the ground, to control standing coniferous and deciduous trees, newly cut tree stumps, tree saplings, brambles, bracken, Nettles, Japanese knotweed and other tough and woody weeds.

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