Japanese Knotweed – Everything You Must Know When Moving Home

If you are about to sell your home or are looking at buying a new home, then this comprehensive guide to Japanese Knotweed is essential reading and will potentially save you thousands of pounds.

Many people aspire to buy a home with a garden, but when viewing a potential new home give little thought to the plants that are in the garden.

But if there is Japanese Knotweed in the garden not only will that seriously devalue the property, but you will almost certainly find it very difficult, if not impossible, to get a mortgage on the property.

Equally, you will find it almost impossible to sell your home if you have Japanese knotweed in the garden, or even if your neighbour has it in theirs unless a comprehensive removal plan is put in place, or is taking place (more on this later).

Whilst this guide will focus on Japanese Knotweed because it is regarded as a real threat to the structure of any property you are thinking of selling or buying, there are structure-damaging plants and trees that are in all probability far more likely to cause significant damage to a property than Japanese Knotweed.

The latest report from RICS (The Royal Institute of Chartered Surveyors) dated March 2022 states that the ‘attitudes are currently disproportionate to the physical risk posed by Japanese knotweed’. As a direct consequence, ‘the media, and as a result the public, have a disproportionate fear of the problem’.

You can read the full report at www.rics.org 

However, for now, buying or selling a home with Japanese Knotweed is problematic at best.

Read on to discover all you need to know about Japanese Knotweed.

Did you know that Japanese Knotweed won the gold medal as the Most Interesting New Ornamental Plant in 1847 from the Utrecht Society of Agriculture and Horticulture?

What is Japanese Knotweed?

Japanese Knotweed is an incredibly invasive weed that grows at a phenomenal rate.

It is not unusual for Japanese Knotweed to grow between 10 and 20cm in a single day, whilst their roots can grow 3 metres deep and have a spread of 7 metres.

The stem of the knotweed can grow up to 3 metres high with leaves that are about 14cm long.

What Does Japanese Knotweed Look Like?

The pictures here show what Japanese Knotweed looks like at various stages of its growth so you will know how to identify it.

However, if you are still unsure if you have Japanese Knotweed then you can send photos to www.knotweedservices.co.uk who will identify FREE OF CHARGE whether your suspicions are correct or not.

Why Is Japanese Knotweed a Problem?

Japanese Knotweed will grow through the weakest points of a structure and seek out cracks in concrete, paving, or tarmac.

As the shoots push through the cracks they will inevitably cause damage to foundations, drains, walls, and paths for example.

It is because these weeds are so destructive and prolific that they are considered such a problem.

It takes only a fingernail-sized piece of the plant to create a whole new plant, so can spread rapidly if the earth around the plant is disturbed or if the plant itself is broken.

The other problem is that once it is established it is incredibly hard to get rid of it.

Using chemicals, it can take up to 4 years to eradicate Japanese Knotweed from an area.

Consequently getting a mortgage or even house insurance on a property with Japanese Knotweed is very difficult.

Can Japanese Knotweed Harm You?

Japanese Knotweed is not toxic nor can it cause burns to humans or animals.

You can touch or pick Japanese Knotweed as it is not harmful at all to humans. In fact, you can even cook it and it is said to have a taste reminiscent of rhubarb.

If you are feeling adventurous why not try out some of these Japanese Knotweed recipes at www.totallywilduk.co.uk 

Is Japanese Knotweed Poisonous to Cats or Dogs?

Japanese Knotweed will not harm your pets at all.

However, you should not allow your pets into any area that has knotweed because they could easily spread the weed just by pulling at the plants.

Do You Have to Declare Japanese Knotweed When Selling a House?

Estate Agent Responsibility for Declaring Japanese Knotweed

Under the Consumer Protection from Unfair Trading Regulations Act 2008, the estate agent must tell you if they are aware that there is Japanese knotweed on a property you may be interested in buying.

If they omit or try to hide this information, they are committing an offence and should be reported to the National Association of Estate Agents. 

All Estate Agents are required to belong to an approved redress scheme under the Consumers, Estate Agents and Redress Act 2007.

Seller Responsibility for Declaring Japanese Knotweed

It is your responsibility to inform the buyer if your land, to your knowledge, has or has had Japanese Knotweed.

On the TA6 property form that the buyers’ solicitor sends you there is a very specific question that asks if the property is affected by Japanese Knotweed.

If the land currently has Japanese Knotweed then you must declare it or you may be sued by the buyer if they subsequently find Knotweed on the land.

As you can never be 100% sure that there is no knotweed in your garden, it would not be wise to choose ‘no’ when responding to this question on the TA6.

To cover yourself from possible legal action in the future it is recommended that you answer ‘not known’.

It is then the choice of the buyer whether to have their own knotweed survey conducted or not.

Surveyors’ Responsibility Regarding Japanese Knotweed

Professional surveyors are trained to identify invasive weeds such as Japanese Knotweed and are expected to have the skills to do so.

There are 3 different surveys that could be carried out on a home you are thinking of buying. During the survey, the surveyor should look for Japanese Knotweed and note that on the house report.

You can read about the 3 different types of surveys that you could have at www.ricsfirms.com

If in the period between the survey and completion of the sale, you discover that the property has Japanese Knotweed but the surveyor failed to see it or to report it, you have no legal recourse to get the money back that you have paid out so far to purchase the property.

However, if having bought the property you subsequently find that there is Japanese Knotweed on your, or a neighbours land, and the surveyor failed to notice it, depending on various factors, you may have a legal case against them, as did Paul Ryb in 2019.

The spread of Japanese Knotweed is not uniform across the UK, some areas have a higher concentration of reported spreads than elsewhere.

So whilst you must be vigilant no matter where you are buying a home, there is a map at www.knotweedhelp.com that shows the areas of the country with the greatest concentration of known Japanese Knotweed plants. 

Buying a Property With Japanese Knotweed

Each bank or mortgage lender has its own set of rules regarding lending on properties that have had or currently have Japanese Knotweed.

Most apply a lending decision on a case-by-case basis.

Where knotweed has been or is, the vast majority will require proof of removal and an insurance-backed guarantee of at least 5 or 10 years.

Note that the cost of Japanese Knotweed removal can run into several thousand pounds which you should either negotiate off the asking price of the property, or you will end up paying for after the purchase.

Any remedial work must have been carried out by a PCA-accredited company. You can find out more about The Property Care Association (PCA) at www.property-care.org

Some lenders will outright refuse to offer any mortgage on a property that has or has had Japanese Knotweed.

You should also be aware that you have a duty of care to your neighbours if any property you buy has Japanese Knotweed.

The knotweed does not even have to spread onto their garden, just having it in the local area can be grounds for their property to be devalued and for them to seek damages from you through the courts.

There are numerous legal cases where a neighbour has successfully sued in such cases, for example, these cases are reported on www.berwin.co.uk   

What Do You Do If You Find Japanese Knotweed in Your Garden?

If you find Japanese Knotweed on your own property you are under no legal obligation to report it to anybody, nor are you under any obligation to treat it or remove it.

You must, however, ensure that it cannot spread onto adjoining land whether that be public or private.

If you fail to stop the spread of Japanese Knotweed to other people’s land you could face fines of up to £2,500 and have an ASBO placed on you.

If you find Japanese Knotweed in your garden and you rent the property it would be wise to inform your landlord as soon as possible. Provide as much information, with photos, as you can. Document and film everything and keep copies.

Some leases may hold you liable for the removal costs of Knotweed so check your contract carefully.

If you can, identify the source of the Knotweed, if it originates on land outside your garden then that landowner will be responsible for any removal costs.

As Japanese Knotweed is so invasive if you discover it within your property boundary it is a good idea to get the professionals to make a survey to determine the extent of the problem.

You will find a list of licensed Japanese Knotweed Removal experts at the end of this guide.

Under no circumstances should you attempt to remove the knotweed by yourself as there are very specific ways in which it must be disposed of. 

Never fly-tip Japanese Knotweed that you have removed from your garden, it is a criminal offence which could lead to a prison term of up to 2 years and an unlimited fine.

Under no circumstances should Japanese Knotweed be placed in garden waste or general waste bins, this is also a criminal offence under the Wildlife and Countryside Act 1981.

What To Do If Your Neighbour Has Japanese Knotweed

Should you discover that your neighbours land has Japanese Knotweed then inform them at the earliest opportunity.

It is best to approach them informally first so that they have the opportunity to rectify the situation before you have to take more official action.

If they fail to take immediate action, follow up your conversation with a formal letter to them and keep a record of any communication you have with them.

In the event that they choose to ignore your formal letter to them and still do nothing, you can obtain a Community Protection Notice (CPN) from the local council or Police who will ensure that the neighbour deals with the problem.

Read more about the scope and the process for obtaining a CPN at www.cieh.org

Where to Report Japanese Knotweed

Although you are under no legal obligation to do so, if you discover Japanese Knotweed and believe that it will cause damage to the local environment, will spread onto your land, or that nobody else has reported it, then contact the land owner or your local council with as much information and photos as you can.

You can find your local council contact details and often a page specifically with details about what to do if you find Japanese Knotweed in your area at www.gov.uk  

If you discover Japanese Knotweed on Network Rail land you can report it to them on 03457 11 41 41 or on their website at www.networkrail.co.uk  

Should you discover that Japanese Knotweed has been fly-tipped then contact the Environment Agency on 0800 80 70 60.

How Do You Get Rid of Japanese Knotweed Naturally?

Using bleach, vinegar or even coffee grinds is an unproven method for killing Japanese Knotweed.

It is possible to control Japanese Knotweed using certain weed killers or herbicide treatments but they cannot eradicate the problem.

Additionally, there are a couple of problems with tackling Japanese Knotweed yourself:

Firstly it is a very long and laborious process that involves re-treating the affected area over many years.

And as previously mentioned it is extremely difficult to dispose of legally.

Finally, any work you carry out yourself will have no insurance-backed guarantee, so when it comes to selling your property or placating your neighbour, you may face some problems.

Many mortgage lenders will refuse to give a mortgage on any property that has had Japanese Knotweed that has not been treated by a PCA-licenced company. 

 So although you can control and eventually eradicate Japanese Knotweed yourself it is not recommended.

However, your circumstances may mean that you have no need for an insurance-backed guarantee or you don’t have the average £3,000 it costs to get the knotweed professionally removed.

There is a comprehensive list of Do’s and Don’ts when tackling Japanese Knotweed yourself at www.wiseknotweed.com which you will find invaluable. 

Japanese Knotweed Removal Experts

There are two main trade bodies that the vast majority of Japanese Knotweed removal companies will belong to.

• Invasive Non-Native Specialists Association (INNSA) 
• Property Care Association (PCA)   

To attain membership any company must go through rigorous assessments and then will be regularly inspected to ensure that they maintain those standards.

Accredited companies will be able to provide an insurance-backed guarantee for any work they carry out which will be recognized and accepted by the vast majority of mortgage lenders.

You will find a list of accredited invasive plant removal experts in your area on both of these websites.

• List of INNSA Members in your area
• List of PCA Members in your area

Other useful resources for tackling and reporting Japanese Knotweed:

• Contact Your Local Council
• Contact the Environment Agency on 03708 506 506
• Network Rail on 03457 11 41 41

You may also like to read:

• Invasive Plants That Could Stop You Buying or Selling a Property. There are other species of plants other than Japanese knotweed that surveyors look for. In this guide, we look at common invasive plants in the UK and how could affect the sale or purchase of a new home.
• Pros and Cons of Buying a House With a Garden. A garden takes a lot of time, effort, and money to maintain. Equally, they are a source of immense pleasure, promote mental and physical well-being, and are a great hobby. Discover whether having a garden is the right decision for you.
• How to Soundproof Your Home and Garden. Noisy neighbours or a busy road are guaranteed to spoil the enjoyment of having a garden. Here we offer some practical ways to help limit the noise wrecking your quality garden time.
• How to Move a Garden to Your New Home. People invest many thousands of pounds in their gardens and often have fond memories attached to certain plants or features. Discover how to pack and move plants and shrubs, garden furniture, and hot tubs, and how to pack your shed for moving home.