How Not To Remove Knotweed | Green Leaf Remediation

Stately Home’s Owner Tears up Tenant’s Garden to Halt Japanese Knotweed

When stately home owner Roger Gawn spotted Britain’s most troublesome weed growing on a tenant’s land, he leapt into action. Reports the Daily Mail.

Using a mini-digger, he uprooted plants, trees and shrubs to ensure he removed all trace of the destructive Japanese knotweed.

But the tenant complained the land had been left ‘like a bomb site’ and this week Mr Gawn, 70, found himself hauled before a court. He was accused of causing more than £3,500 damage to the garden that Robert Adams rents from him at the Coach House, part of the 17th century Grade I listed Melton Constable Hall in Norfolk.

Widower Mr Adams, 80, who has lived in the three-bedroom semi-detached house for 46 years, said he had not been warned that his garden would be dug up.

But magistrates cleared Mr Gawn on Wednesday after he explained that the knotweed would have caused widespread damage if he had not acted. He had intended to replant the area he dug up, he said.

After the hearing, property developer Mr Gawn, who bought the estate in 1986, said: ‘Justice has been done and I am very grateful that the truth has been seen. I have had difficulties with the tenant ever since I inherited him. This is just another in a series of incidents.’

The disputed area did not form part of the garden leased by Mr Adams, who pays £540 a month in rent – around half the market value – he claimed.

The row began in March last year. Mr Adams told King’s Lynn magistrates he popped out to the shops and returned to find the garden he had planted with his late wife had been destroyed.

‘There was nothing left in the garden, it looked like a bomb site.

‘The lawn didn’t exist anymore, there were holes where the trees had been, there were lumps of earth and craters all over the place.’ He said ‘it would have been fair’ for Mr Gawn, who had often complimented him on how well he kept the garden, to have written stating his intentions.

Prosecutor Fred Sagoe said there was a difference of opinion about whether Mr Gawn was entitled to do what he did and whether it was reasonable.

Mr Gawn told the court he acted after he discovered a crack in a large brick-built potting shed that he was seeking to convert into a home for another employee.

‘My gardener and I started to clear away stuff and we discovered the Japanese knotweed within minutes,’ he said. ‘It became obvious that it was the knotweed which was destabilising the building.

‘I dug everything up safely with root balls intact and set aside the plants for replanting.’

Mr Gawn admitted he had not warned Mr Adams about the work. But he explained: ‘I had to deal with a real problem and I had to get on with it.’ He denied deliberately carrying out the work when his tenant was away.

Simon Nicholls, for Mr Gawn, said Japanese knotweed was a ‘pernicious’ plant that could cause serious damage and it was an offence to allow it to grow.

Presiding magistrate Nigel Stringer said Mr Gawn had ‘acted in a reasonable manner’ and ‘there was no criminal intent’.

Mr Adams was not available for comment last night.

So, what is Japanese Knotweed?

Japanese knotweed (Fallopia japonica) is an extremely fast-growing weed that spreads quickly. In winter knotweed dies back to ground level but in late spring, early summer the stems emerge from rhizomes deep underground and can grow to over 7ft tall, suppressing all other plant growth around it. The stem growth is renewed each year from those strong, deeply-penetrating rhizomes which are creeping underground stems.

it is extremely difficult to remove by hand or with chemicals and there is now legislation which covers its eradication and control.

How do you identify Japanese Knotweed?

Japanese knotweed is a perennial weed, producing tall canes, up to 2.1m/7ft tall during summer. The canes have characteristic purple flecks and produce branches from nodes along its length. These branches support shovel-shaped leaves. A qualified Knotweed Specialist will be able to identify knotweed quickly.

Where did Japanese Knotweed come from?

A Dutch doctor called Phillipe von Siebold came to the UK in the late 1840’s and began to sell Japanese Knotweed to botanical gardens and high society figures. By 1869 it became available for general sale in the UK and farmers began to use it as feed for their animals. By the late 19th century gardeners encouraged people to buy and plant knotweed in their gardens to bring a touch of greenery. Little did they know the devastating effects knotweed could have from its rapid growth and roots.

The effect of it being introduced in homes and public gardens resulted in it spreading rapidly in the wild. By the 1930’s the impact of knotweed became known and the bright evergreen weeds once positive reputation, quickly diminished.

By 1998 The Wildlife and Country Act made it an offence to introduce Japanese Knotweed into wild spaces due to its invasive nature.

Knotweed Myths, Misconceptions and Facts

Knotweed Facts:

  • Its common name is Japanese knotweed
  • Its Latin name is Fallopia japonica (syn. Polygonum cuspidatum)
  • It affects waysides, beds, borders and paving areas
  • The tiny rhizomes are rooted deep underground and the tiniest rhizome will enable the weed to grow rapidly and spread
  • It dies back in winter but do not be fooled by this as it will rear again, and grow fast in late spring through to autumn
  • It needs to be treated by a Knotweed Specialist to eradicate the invasive weed and its roots

Knotweed Myths:

  • It will grow through solid concrete
  • It will damage foundations if they are exposed to it
  • It will cause structural damage to a building if it is growing nearby
  • Pouring salt, diesel, caustic soda, turpentine, fairy liquid on the plant or into the ground will eradicate it
  • Digging up the roots of knotweed will eradicate it

In summary, if groundwork and construction have been completed to a good standard previously then knotweed will not grow ‘through solid concrete’ and it will not destabilise solid foundations or cause structural damage. It can, however, penetrate damaged or cracked foundations and structures and cause more damage.

The truth about knotweed is that it is a wild plant which grows and spreads rapidly, taking over other vegetation around it and it is very difficult to completely remove.

About South Wales Knotweed

Remove Knotweed South WalesSouth Wales Knotweeds is a local and family-run, Invasive Weed Management company. We launched in 2013 and are fully qualified Japanese Knotweed Certificated Surveyors (JKCS) through the Property Care Association.

We specialise in eradicating Japanese Knotweed (Fallopia Japonica), along with other invasive plant species and ‘general nuisance weeds’ found in the UK. We offer our services for residential premises and land earmarked for housing and commercial developments. We offer a professional and reliable service every time and are experts in Japanese Knotweed and its eradication. Due to Knotweed’s invasive nature removing the plant and root ball will not always fully remove it from an area, however, we have many removal methods and will always conduct a thorough site visit to advise you on the best solution to eradicate.

Our expert knotweed removal and treatment services are available throughout South Wales including Swansea, Cardiff, Newport, the Valleys and West Wales.

Knotweed Legislation

We are experts in the strict legislation covering the handling and disposal of Japanese Knotweed and will always offer you advice and the best solution for your property or land.

Our knotweed treatment methods are endorsed by the Environment Agency Codes of Practice and the industry trade body, The Property Care Association, and our methods will be tailored to suit you and the removal area.

Our Knotweed Control and Removal Methods

There are many ways to control and remove knotweed and you should always use a specialist and qualified company who fully understand the legislation and techniques that must be used. Always do your research thoroughly when looking for a company to eradicate and remove Knotweed as there are many out there who do not have the specialist legislation knowledge needed for the correct and legal removal method.


Stem-injection is a low impact method of removing knotweed. It is normally used for smaller infestations and is used when the knotweed has established itself amongst other plants that you don’t want to be removed as there is less risk of damaging the surrounding vegetation. It can also be used in areas where there is a watercourse due to it being a less risky method of removal. The stem-injection process can be carried out in dry or inclement weather conditions and the soil need to remain undisturbed following the treatment.

Foliar Application is a spray method of knotweed removal and is used when the treatment can be repeated over several of its growing seasons. The knotweed is sprayed with an approved herbicide and the process is conducted 2 to 3 times in the first year depending on the size of the knotweed and then once in the following year. The process needs to be done in dry weather and the soil undisturbed in subsequent years.

Weed Wiping

The Weed wiping method can be done in areas where there are other plants that you don’t want impacted, much like the Stem-injection method. The knotweed leaves are wiped with a sponge soaked with a suitable herbicide meaning only they are impacted.

Bund / Stockpiling

Bund or stockpiling is a combined treatment of stem-injection or foliar application which is followed by excavation of the underground material and removal of the soil to a different section of the site. The new shoots that emerge are then subjected to further herbicide application. This method of removal is quicker than the more commonly used methods which are repeated annually and when done correctly it allows a developer to start using the land more quickly.

Cell Burial / Root Barrier

Cell Burial or utilising a Root Barrier will avert the substantial costs of transporting the knotweed soil and waste to landfill, however, the site needs to be big enough for the knotweed material to be buried to a minimum depth or, if encapsulated within a geomembrane, it can be buried closer to the surface. Root barriers can be installed both vertically and horizontally and this method is used when there is a risk of cross-boundary contamination.

Excavation & Removal Off Site

Excavation & Removal of knotweed material off-site is a legitimate and swift control option. It does have its advantages for development sites when done correctly, however, the significant logistical challenges of this removal method are challenging.

The secure movement of the material to landfill is costly as there is a high risk of the knotweed spreading. There is a considerable duty of care requirements under the Environmental Protection Act (EPA) 1990 with this method of removal. We always advise that the Excavation & Removal method should only be used as an absolute last resort and this will be established by us during our site visit.

Site Assessment and Validation Report

We will conduct a site visit to confirm if a plant is or isn’t Knotweed. There will normally be no fee involved however this is dependent on the location. We may also be able to identify knotweed by reviewing photographs and we can discuss this with you. Verbal confirmation to the customer is often enough, however, we can confirm this officially in writing, along with an estimated cost of removal if needed for a mortgage lender.

We will document our findings accurately, however, we are unable to categorically confirm that Knotweed does not exist on a site as it could be possible there is no visual indication it is present. During the winter months when Knotweed may not be visual we will meticulously assess if Knotweed is underground.

Site Assessment Report

The rationale of a SAR is to provide clear guidance to the mortgage lender or purchaser regarding the risk of the existence of Knotweed on or close to a property. We will provide a summary of treatment options, map out locations or special features and confirm whether any Knotweed has damaged or has the scope to damage any permanent structures. The content of the SAR is then analysed by the mortgage lender to form a sound view if there is, or isn’t a risk in lending.

Our treatment and removal services are provided to home, business properties and development sites. We can consider a staggered payment schedule for any work that does not involve a 3rd party, and for customers who need pre-payment evidence for their mortgage lenders.

Please call us on 01269 591651 and one of our expert team will be happy to help you with any questions you may have on Knotweed and its removal.