Japanese Knotweed Myths, Misconceptions and Facts
There is a lot of misleading information (myths) as to how you can control and remove Japanese Knotweed as well as what is the best course of action to take.
Pouring salt, diesel, caustic soda, turpentine, fairy liquid on the plant or into the ground are some of the common myths which have been shared over the years, of which some are not safe or a way to successfully remove Japanese Knotweed.
There are many Japanese Knotweed Specialists similar to Green Leaf Remediation across the UK who will have the qualifications, extensive experience and licenses needed to safely and effectively control Japanese Knotweed. There are some businesses that claim to be specialists, however, they don’t have the qualifications needed to safely and effectively control the invasive weed. It’s extremely important to do your research and ask a lot of questions before you employ someone.
You should always use a fully qualified Japanese Knotweed Certificated Surveyor (JKCS) who is registered through the Property Care Association as Green Leaf Remediation is. We are experts in the identification, treatment and control of Japanese Knotweed and this is the core of our business. Our JKCS Surveys are recognised by mortgage lenders and will save you a lot of time and money in the long run.
Unlike some contractors who will alarm you with their Japanese Knotweed Mths and Facts, we are firm believers in telling the public and our customer’s exactly what Japanese Knotweed can & can’t do.
Japanese Knotweed Myths
“It will grow through solid concrete”
“It can destabilise foundations”
“It has the potential to cause structural damage”
“Japanese Knotweed can damage buildings especially if left to grow unhindered for a number of years”
“This invasive plant can have such a dramatic effect on structures, foundations & concrete”
Japanese Knotweed Facts
The truth about knotweed is, that if a structure, building or foundations are solid then it is almost impossible for Knotweed to grow through a slab of solid concrete, nor will it ‘destabilise solid foundation’s. In fact, there are very few reported incidents, whereby the plant has had a ‘negative effect’ on any ‘solid structure’.
Knotweed True or False?
In some cases, you can treat newly emerging and unestablished Japanese Knotweed with an approved herbicide for just one year and it MAY have an impact and not re-appear in the following years. However, in the majority of cases, a repeated herbicide application programme over several years will be required to permanently remove the weed from your property or site. The longer the plant has been prevalent, the more difficult it will be for the herbicide to penetrate the crowns & rhizomes (root system). One or two precise applications of herbicide by a specialist will cause disruption to the plants’ growth cycle, however, you shouldn’t accept assurances or guarantees from anyone who claims they will eradicate Japanese Knotweed via the herbicide method in one year or one growing season. There are other methods of removal that can be used if you have a site that you are developing and our specialist methods of removal can be found here: Control Methods
Japanese Knotweed’s crowns & rhizomes (root system) are prevalent and will spread quickly underground which is what makes it extremely difficult to remove if you have got the knowledge, experience and qualifications. Whether it is in its dormant or peak growing season 60% of the plant is underneath the ground, therefore, cutting the stems and growth above ground will not stop it from growing or prevent it from spreading, in fact, it will spread much more quickly if it is disturbed.
In summary, the source of the problem lies beneath the ground, not above and this myth will do nothing to control the plant in the long term.
Pulling the plant from the ground will do nothing to achieve eradication. It will leave the rhizome or crown (root system) within the soil and it will spread even more so underground and then re-appear above ground and in more mass in its peak growing season. Although pulling the plant from the ground will visually remove it over time germination and regrowth will occur.
Having Japanese Knotweed on your property is not an offence, however, under Section 14 (2) (a) of the Wildlife & Countryside Act 1981, it is an offence to ‘plant or otherwise allows Japanese knotweed to grow in the wild’. In addition to this, allowing Japanese knotweed to spread onto neighbouring land or property can be considered a private nuisance as opposed to a statutory nuisance.
Community Protection Notice (CPN) under s.57 of The Anti-Social Behaviour, Crime and Policing Act 2014 can be used to enforce someone to control or prevent the growth of Japanese knotweed or other plants that are capable of causing problems if they are allowed to spread in a community. Local councils and the police (in most cases it will be the local council) will have the power to issue notices for invasive non-native species like Japanese Knotweed and, if necessary, force them to take whatever measures are required to prevent any detrimental effect on the quality of life of the community. Breach of any requirement of a community protection notice, without reasonable excuse, would be a criminal offence that would be subject to a fixed penalty notice or prosecution.
The primary objective of a Community Protection Notice (CPN) is to prevent or to seek a resolution (of sorts) to the ‘unreasonable behaviour’ that is having a negative impact on the local community’s or individual’s quality of life. Any person aged 16 years or over or business can be issued with a notice and it will require the behaviour to stop and enforce reasonable steps to be taken to ensure it is not allowed to spread again in the future.
Yes, you can actually eat Japanese Knotweed, however, although it goes without saying, it is best to avoid it once it’s been treated with herbicide. It is often called ‘Wild Rhubarb’ as the shoots contain water and are similar in taste to the Rhubarb sold commercially in supermarkets. Very much like Hogweed, it is another edible plant (during the early stages of its growth cycle) that grows in the wild in the UK.
In most cases Japanese Knotweed won’t cause damage to sound structures, buildings or foundations, however, it will and can quickly grow through any cracks or damage in bricks, concrete or pipework which can result in the damage becoming worse. It is really important if you think you might have knotweed growing around your property that you ask an expert like South Wales Knotweed removal to come out and identify the plant and advise you of the action you need to take before it takes holds and spreads.
This is untrue, there are some mortgage providers who will offer to lend on a property or site where there is evidence of Japanese Knotweed. Some mortgage providers won’t even consider lending in these circumstances so you will need to do your research on which ones will. They will also require a Japanese Knotweed Certified Survey which will detail where the knotweed is in regards to the property and boundaries, the extent of the knotweed, the risk of the knotweed spreading as well as the advised treatment method and removal costs. Our JKCS Surveys are recognised by mortgage lenders and will save you a lot of time and money in the long run whether you are a house or site seller or purchaser.
Our Japanese Knotweed Management Plans (JKMP’s) are all supplemented by a 10-year Insurance Backed Guarantee (IBG). The JKMP ‘remains’ with the property so if there is any future property transfer it becomes the possession of the new owner, irrespective of how many times the property exchanges hands. This offers reassurance to the buyer and normally increases the chances of the property or site selling.
Japanese Knotweed is a perennial weed that grows and spreads quickly from one tiny fragment of crown or rhizome if it isn’t treated and managed by a specialist. Its crown and rhizomes (root system) will suppress other plants growing around and it spreads extensively and quickly underground. Well-established shoots can grow more than 3 metres high and can colonize the soil within a few years. In the height of its predominant growing season, 60% of its roots are in the soil underground so removal is very difficult without the support of a JKMP from a specialist.
Japanese Knotweed is almost impossible to control and remove yourself, however, a qualified specialist who has the experience and knowledge to use the removal and control method can.
It can take anything up to 5 years to completely remove Japanese knotweed through specialist chemical treatments carried out by a Knotweed specialist. The time it takes will depend on the size of the area. Japanese Knotweed can be completely eradicated through excavation and it is dug out of the ground by a Knotweed specialist and safely removed to prevent the risk of it spreading. This method is more commonly used when a development site has knotweed and the construction needs to start quickly and must always be carried out by a knotweed specialist.
You should always tell your mortgage lender on your mortgage application that the property you are looking to buy has Japanese Knotweed. Mortgage lenders are cautious with properties that are affected by knotweed, however, it isn’t impossible to get a mortgage. We can help with a site survey and certification for a mortgage.
In the UK, a property seller is legally obligated to declare if knotweed is present on the land of the property they are selling. Failing to document this on the TA6 Property Information Form can result in a claim of misrepresentation being filed against you, as well as your property sale falling through.
It is not an offence to have Japanese knotweed on your land or property and it isn’t a notifiable weed. However, under Section 14(1) and (2), of the Wildlife and Countryside Act 1981 it is a criminal offence to plant Japanese knotweed or otherwise cause or allow it to grow in the wild or spread onto neighbouring land or property.
Japanese Knotweed can grow up to 20cm a day and in the height of its growing season, its stem can reach up to 3 – 4 metres high. Underground, the roots, rhizomes also grow rapidly and can spread up to 7 metres horizontally and 3 metres deep. As soon as you think you could have knotweed present on your property you should get a specialist like South Wales knotweed to come and formally identify it and advise you of what you need to do.