How to Kill Japanese Knotweed
Japanese Knotweed is a wilful defender of any ground that it has conquered and a sneaky underground infiltrator, liable to pop up wherever it pleases.
Should you find this invader on your property the first thing you will probably do is to try to find out how to get rid of or kill Japanese Knotweed because the sight of it on your property is enough to strike dread into the heart of any property owner, bearing in mind all the negative media coverage that Japanese Knotweed has been getting in the past few years.
In the UK the Environment Agency describes Japanese Knotweed as “indisputably the UK’s most aggressive, destructive and invasive plant”, along with all the negative environmental and economic impacts it has caused, it has also had an effect on residential property sales.
Potential buyers have in some cases experienced difficulties securing a mortgage on a property if it’s affected by Japanese Knotweed, some lenders reject outright any property affected by Knotweed, others take a more practical view and lend where the Japanese Knotweed infestation is being treated by a reputable firm.


Japanese Knotweed is not an easy plant to control and trying getting rid of or kill Japanese Knotweed yourself is not easy and takes patience! The most common method is to use a glyphosate herbicide but this will require a high dosage and it will not be eradicated after just one dose, it will require repeated doses to completely rid your property of Japanese Knotweed and may take a few seasons.
These products should be applied responsibly, always read the pesticide product label to make effective and economic use of the product, which by doing so minimises risks to people, animals and the environment.
Although root systems can be killed by herbicides, they are often so large that weed killers don’t reach deep enough into the plant to do their work properly. Even when the plant is dead, the soil around it may contain pieces of rhizome, to guarantee it doesn’t return the soil must be excavated and carefully taken away.
In Ireland Japanese Knotweed is classed as a ‘controlled waste’ under the Environmental Protection Act. This requires disposal at licenced landfill sites. The Japanese Knotweed Company is fully licenced to safely remove the weed/soil from any site to licenced landfill sites.
Remember…
Japanese Knotweed thrives on disturbance and invades environments where soils are routinely disturbed and transported.
- Do not strim, cut, flail or chip the plants as tiny fragment can regenerate new plants and make the infestation harder to control
- Do not attempt to dig out Japanese Knotweed, this can actually encourage the plant into growing faster, therefore colonising an area more aggressively
- Do not move or dump soil which may contain plant material as this may also add to its spread.
- Do not attempt to pull the plant out of the ground, as this can expose part of the infectious crowns, stimulating growth
- Do not use unlicensed herbicides close to any watercourses, plants or wildlife
- Do not compost any part of the plant as due to the resilient nature of knotweed it could survive and grow on when the compost is ready for use
- Do not dispose of Japanese Knotweed in garden waste allotments as this just transport the plant to new locations
- Do not spread any soil that has been contaminated with Japanese Knotweed rhizome as new plants will sprout
- Do not do break the law – Remember it is an offence if you cause the spread of Japanese Knotweed either intentionally or unintentionally.