Japanese Knotweed Control Methods: How We Do It

Control Methods

All our Japanese Knotweed treatment methods are endorsed by the Environment Agency Codes of Practice and the industry trade body – The Property Care Association which can be tailored to suit you as the client. We are happy to consider a staggered payment schedule for any work that does not involve a 3rd party, who may require evidence of pre-payment in full from the outset (mortgage lenders as an example).

New Logo South Wales Knotweed


This is an ideal method of treatment which is low impact and carries little risk of disrupting the growth of other plants. Normally utilised for smaller infestations, particularly whereby the Japanese Knotweed has managed to establish itself amongst desirable vegetation or perhaps being close to a watercourse. Stem-injection can be conducted in dry or inclement weather conditions and it is essential that the soil remains undisturbed following treatment.

Foliar Application

Generally speaking, along with stem-injection, providing the Japanese Knotweed can be treated over several growing seasons, foliar spray is often the most pursued method of treatment. This involves spraying the plants with an approved herbicide. Treatments are normally conducted on two or dependent on the size of the infestation, possibly three separate occasions in the first year and on one occasion in subsequent years. This method requires dry weather and also requires the soil to remain undisturbed in subsequent years.

Weed Wiping

A simple method, which like stem-injection, has the benefit of being low impact on other surrounding foliage, meaning only the plant itself will be affected.


Before & After

Before and After knotweed control

Bund / Stockpiling

Creating a bund or stockpiling is essentially a combined treatment method of stem-injection or foliar application, followed by excavating the underground material and removing the soil and material to a different section of the site, where the emergence of ‘new shoots’ can be subjected to further herbicide application. Done correctly, control is achieved far quicker than conventional herbicide application, therefore ‘saving’ the landowner several years. This method is particularly useful on building plots / development sites as work can continue at the original infestation site.

Cell Burial / Root Barrier

Providing there is adequate space on site, creating a Cell Burial or utilising a Root Barrier will avert the substantial costs of transporting the soil and waste to landfill. Cell burial involves burying the Japanese Knotweed material to a minimum depth or if encapsulated within a geo-membrane, burial can commence closer to the surface. Root barriers can be installed both vertically (normally when there is a risk of cross-boundary contamination) and horizontally.

Excavation & Removal Off Site

Although Excavation & Removal of Japanese Knotweed material off site, is a legitimate and swift control option and has its advantages for development sites (done correctly!), we are not advocates of pursuing this method as this raises significant logistical challenges. A high risk of spreading, the cost implication in conveying the material to designated landfill and amongst other issues, there are also considerable duty of care requirements under the Environmental Protection Act (EPA) 1990. We are however, happy to act in a consultancy role as clerk of the works providing certain conditions are met with the landowner / developer.

Excavation & Removal should only be used as an absolute last resort.

All of these treatment options and removal services are provided to homes, businesses, housing & commercial developments along with properties throughout South Wales including Swansea, Cardiff, Newport and rural locations.