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Japanese Knotweed Removal Cost

By Kim

Last updated 17th June 2024 - Reading time: 21 mins

At a glance

The average cost to remove Japanese knotweed is around £4,000
The job will take approximately 1 - 2 days to complete

In this article, you'll discover the following:

A complete pricing breakdown which includes cost factors to consider, how to identify it, along with what such a task usually involves
How long the job should approximately take and a general overview of what kind of jobs can be performed
How to find and hire a Japanese knotweed removal specialist

Want to discover the costs of removing Japanese knotweed?

Japanese knotweed is one of the most invasive plants in the world, and dealing with it can be a real pain as well as being rather expensive.

Because the job of getting rid of japanese knotweed can vary drastically in terms of complexity and the required time it will take to complete, the average price can be anywhere from £1000 and as much as £20000.

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We've created this complete guide to show all prices involved in different knotweed removal methods, labour fees and much more!

So, why not take a read below?

Average Cost of Removing Japanese Knotweed:

Depending on the complexity of the job, it usually takes: 1-2 days

£4000

How Much Does It Cost To Treat Japanese Knotweed?
- Japanese Knotweed Removal Prices
Labour Costs and Timescales
Additional Costs
Cost Factors of Removing Japanese Knotweed
What's Involved in Removing Japanese Knotweed?
Identifying Japanese Knotweed
How to Get Rid of Japanese Knotweed Yourself
What Does Japanese Knotweed Do?
Types of Japanese Knotweed Treatments
Japanese Knotweed Law and Legislation
Emergency Japanese Knotweed Removal
Hiring a Japanese Knotweed Remover
FAQs
Sources

How Much Does It Cost To Treat Japanese Knotweed?

Japanese knotweed is one of the most damaging and toughest plants in the entire world. It can grow at a menacing rate and can be incredibly challenging to eradicate.

Japanese knotweed can grow almost anywhere, including underground up to a depth of three metres and can have a horizontal spread in any direction up to up to seven metres. Its strength can cause damage to concrete, house foundations, and patios – there are no barriers that this pest can’t take over.

If you discover Japanese knotweed growing somewhere around your property, it is essential that you act fast. If you leave this pest for too long, it can begin to grow underneath your home and even through your walls and floors.

There are a number of different types of Japanese knotweed removal and prices can vary from £1000 all the way up to £20000 for an average-sized garden in the UK. These prices will depend on the size of the infestation, the ease of access to your home, and the type of removal that you choose to carry out.

Hi - I have been told that I may have japanese knotweed in the back garden, how do I go about checking this and then removing it? Do I need a specialist?

"You NEED a specialist to remove the knotweed as they need a licence to remove it from ANY property or land. Make sure they are registered as if someone removes it and doesn't have a licence to do so then YOU would also be fined too along with the company that removed it. Knotweed is an invasive species and requires specialist and controlled removal and cutting, the roots of the plant go down over 6 feet deep and spread out so is very hard to kill completely, it spreads fast and wildly... Good luck"

GSJ Home and Garden

Japanese Knotweed Removal Prices

Below is a table of prices you should expect to pay for various parts of a Japanese knotweed removal and treatment job.

Size of Treatment Area	Minor (<49m²)	Intermediate (50m² – 99m²)	Major (100m²-499m²)	Severe (500m²-1000m²)
Herbicide Treatment	£1000-£2950	£3000-£4950	£3950-£6950	£5000-£12000
Sifting and Screening	£1750-£4950	£5000-£9950	£10000-£35000	£35000-£50000
Excavation and Root Barriers	£1750-£4950	£5000-£9950	£10000-£35000	£35000-£50000
Excavation and on-site relocation with ongoing herbicide treatment	£4000-£9500	£9000-£14950	£11000-£20000	£15000-£30000
On-site Burial	£4000-£14950	£10000-£20000	£15000-£35000	£30000-£70000
Full Excavation and Removal	£4000-£20000	£14000-£39000	£35000-£120000	£100000-£200000

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In most domestic cases, a herbicide treatment is the easiest and cheapest solution to a Japanese knotweed problem.

Labour Costs and Timescales

Identifying and removing Japanese knotweed is not an easy job and is one that should be carried out by a professional.

A specialist Japanese knotweed contractor will charge around £20-£50 per hour.

The contractor will need to attend the site to identify if the weed is actually Japanese knotweed and then they will conduct a plan with you to remove it. The removal process can take a very long time to get rid of it completely.

The first stage will usually involve some removal and treatments with herbicide, and this part of the job will usually last less than a day for small areas such as domestic homes. This will usually not eradicate the problem completely. You should expect to have to have follow-up treatments for up to five years before your knotweed problem is completely taken care of.

Additional Costs

There are a number of additional costs that you may need to think about when undergoing a Japanese knotweed removal. Below is a list of some of the additional costs that you may need to consider with this type of job:

Garden Waste Removal – Garden waste removal will cost around £100-£200
Laying Turf – Laying turf for a 50m² garden costs around £650-£750
Artificial Grass – Laying artificial grass for a 50m² garden costs around £3500-£5000
New garden fence – A new garden fence will cost around £500-£1500
Skip hire - A one-weekskip hire will cost you around £200-£250

Cost Factors of Removing Japanese Knotweed

There are a number of things that may affect the cost of a Japanese knotweed removal job. Below is a list of things that may affect the cost of this type of job.

Size of the Affected Area

The size of the affected area will greatly affect the cost of your Japanese knotweed removal. For example, a herbicide treatment on an area below 49m² will cost around £1000-£2950 whereas a herbicide treatment on a 500+m² area will cost around £5000-£12,000. So, you can see the size of the area can have a big difference in the cost of removing your Japanese knotweeds.

Type of Treatment Needed

The type of treatment needed on an area can affect the overall cost of the job. For example, a herbicide on an area below 49m² will cost around £1000-£2950 whereas a full excavation and removal on the same size of area will cost around £4000-£20000. So, you can see from this that the type of job required can greatly affect the overall cost of the job at hand.

Ease of Access to the Area

The cost can be affected by the ease of access to the area. If your property is located in an area that is difficult to access, this can result in the job taking a lot longer and so the labour costs will be greatly increased. On average, a Japanese knotweed specialist will charge around £20-£50 per hour, and so additional time on the job can really add up.

Extent of Japanese Knotweed Growth

Similarly, the extent of the Japanese knotweed growth can affect the overall cost of the job. The more knotweed that needs to be treated, the longer the job is going to take and therefore the higher the overall cost will end up being due to the extra time and work needed.

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What's Involved in Removing Japanese Knotweed?

Japanese knotweed needs to be completely eradicated in order to ensure that it doesn’t return. Removing the knotweed root strands is a very difficult task and often requires the use of a mechanical digger. A mechanical digger hire will usually cost around £200-£300 per day.

You will also need to dispose of all materials, including any contaminated soil. It is important to remember that Japanese knotweed is a controlled waste in the UK. With this in mind, you must take it to a specialist landfill site.

The best method for homeowners wanting to eradicate their Japanese knotweed problem is to go down the herbicide treatment route. Below is a step by step guide on how to go about this:

Step One

The first step is to complete a risk assessment. You should take a look at the area surrounding your property. Are there any schools, children’s playgrounds, or communal areas that may be affected by drifting spray? Are there any nearby rivers, streams, canals, or ponds that may be affected?

You should communicate with your neighbours to let them know when the work is due to take place so that they can ensure their pets and children remain indoors during the treatment time.

Draw up an action plan so that you know exactly what needs to be done. The best time of year to treat Japanese knotweed is between late spring and early autumn. This is when the plant is in full growth.

Step Two

The second step involves ensuring that you have all of the relevant safety equipment needed. You will most likely need to have the following pieces of safety equipment as a bare minimum:

Overalls
Safety mask
Gloves
Face Shield
Sheets and Tarpaulins
Rubble Sacks

Step Three

You will need to check the weather on the day that you have planned to tackle your Japanese knotweed problem.

The majority of herbicides that are used to treat knotweeds will also affect other plant life too. With this in mind, you should make sure that you carry out the work on a dry day with no chance of rain forecast. If you are using a spray application, you should also avoid windy days.

Step Four

The best way to treat Japanese knotweeds with herbicide is to use a garden sprayer. However, this can be dangerous in an area near to water sources or close to areas such as schools and playgrounds. In these cases, the herbicide can be applied using a roller, cloth, sponge, or brush. Be sure to use gloves and use tarpaulins and covers to protect any other plants, ponds, and grass.

The herbicide should cover the leaves and stems of the Japanese knotweed. It is also recommended that you inject some of the herbicide directly into the stems. The place for this is near the first node, just above ground level.

A professional knotweed contractor will use a specially designed tool for this; however, you can simply cut the stem and pour some of the herbicide directly into it.

Step Five

The next step is the clean-up step. Any Japanese knotweed that has been cut loose should be placed inside some study plastic rubble sacks. These sacks should only be disposed of at a specialist landfill site.

Some councils in the UK offer free specialist collection services for Japanese knotweed. We would recommend getting in touch with your local council to see if this is something they offer in your area.

Step Six

The last step involves repeating the treatment. One single treatment simply won’t be enough to completely diminish your Japanese knotweed problem.

It is recommended that you repeat the treatment 2-3 times per year and continue to do this for around 3-5 years until the Japanese knotweed is completely gone and doesn’t continue to grow back.

Identifying Japanese Knotweed

Japanese knotweed is a type of weed that spreads incredibly rapidly. It grows extremely high and can penetrate through extremely tough materials including flooring, walls, and roofs.

The weed arrived here from Japan in the mid-nineteenth century by a German-born botanist named Phillipp von Siebold who discovered the plant growing along the side of volcanoes.

It was initially praised for being a beautiful plant and for its potential to provide feed for animals. It was originally sold at nurseries for people to plant as they wished.

It spread through the country by people sharing cuttings of the plant as well as through movement of water and soils during construction and when building new roads. Nowadays, it is known as a nuisance as it can cause destructive damage to properties and take over large areas of land.

Japanese knotweed is a unique-looking plant that has a few specific features that make it easier to identify it.

The bamboo-like shoots have noticeable purple spots on them, and they produce branches from nodes all the way along. The leaves that grow off the branches are heart-shaped and grow up to 14cm in length. They also have a noticeable zig-zag pattern along the stems.

When it first breaks through the ground, you will notice red-coloured shoots. This may be a good early indication that you have knotweeds growing in your area.

The plant will begin to bloom around the end of July and clusters of cream-coloured flowers will begin to show. These flowers can attract a lot of bees.

As autumn arrives, the plant dies back, and you are left with brown stems. If you notice any of the above characteristics within a plant in your area, you may have a Japanese knotweed problem.

If you are still unsure, you may want to hire a professional to inspect your area so that you can treat your weed problem as early as possible.

How to Get Rid of Japanese Knotweed Yourself

A professional Japanese knotweed contractor will carry out all of the relevant safety precautions as needed in a job like this and they will also have the means to dispose of the waste in an effective manner.

Despite this, if you only have a small amount of Japanese knotweed present, you can carry out a herbicide treatment yourself via the steps above.

Glyphosate-based products are best for controlling Japanese knotweed. A typical 5L bottle of Glyphosate-based herbicide costs around £30-£50.

The cost of a doing a Japanese knotweed treatment yourself is considerably less than if you were to hire a professional to carry out the treatment. However, you do need to be very careful when completing the work.

For a typical average-sized garden with a medium-sized infestation, you will pay around £50-£70 per year for your disposable safety gear and roughly £100-£150 per year for the herbicide. Also, a sprayer will cost around £18-£25.

What Does Japanese Knotweed Do?

Japanese knotweed can grow by up to 20cm per day. This is extremely fast growth and is why it can easily and rapidly take over an area.

Japanese knotweed can grow through concrete and tarmac and the roots of this ferocious weed can grow up to 3m deep in the ground.

There are no natural predators to tackle this type of weed. This means that it can continue to grow uninterrupted. The sheer height of the plant can block out sunlight from neighbouring plants, causing them to die through lack of sunlight.

Types of Japanese Knotweed Treatments

There are a number of different treatments for Japanese knotweed. Below is a list of the different types of treatments that can tackle a Japanese knotweed problem.

Herbicide Treatment

A herbicide treatment is the most cost-effective Japanese knotweed treatment. For an average domestic garden, you should expect to pay around £1000-£2950 for a herbicide treatment.

The treatment involves carefully and methodically managed visits where a chemical is sprayed onto and injected into the knotweed over a sustained period of time. This exhausts the plant and prevents it from spreading.

Excavation

Excavation is the fastest Japanese knotweed removal process, but it is also much more expensive than a herbicide treatment. For an on-site excavation with root barriers put in place to prevent the growth, you would be looking at paying around £1750-£4950 for the work to be carried out on an average-sized garden.

The job involves using plant machinery to physically pull out the infected soil. Any traces of knotweed or infected soil will then be disposed of in a controlled process.

Sifting and Screening

Excavation can be a very large and costly job. The less contaminated the soil is that you have, the lower the costs will be for an off-site burial.

This is where a sifting and screening job comes in handy. For an average-sized domestic garden, sifting and screening will cost around £1750-£4950.

The job involves using plant machinery to scrape back a thin layer of soil which is then sifted or screened by a Japanese knotweed surveyor. This involves digging out infested soil and screening it to remove the rhizomes.

The screened soil can then be re-used on a different area of the site, reducing the amount of waste that needs to be disposed of.

Burial on Site

An on-site burial saves the costs of having the infected soil and knotweed disposed of at a specialist landfill. Instead, the soil is buried on-site. The cost for an on-site burial on an average-sized domestic garden will cost around £4000-£14950.

The job involves removing all of the infested soil and knotweed present and then burying these waste products at a different area on the site to a depth of at least five metres.

This is a more cost-effective method than having the waste transported to be disposed of off-site.

Full Excavation and Removal Off Site

Sometimes the only way to remove your knotweed problem is to get rid of it through an excavation and removal of the waste off-site. A full excavation and removal off site for an average-sized garden will cost around £4000-£20000.

The process involves digging out and removing all of the existing knotweed and digging out any affected soil. These waste products will then be taken away and disposed of in a controlled manner at a specialist location sway from the site.

Japanese Knotweed Law and Legislation

Japanese knotweed is an invasive species of plant and, therefore, it is the responsibility of the landowner to ensure that this plant doesn’t spread into neighbouring lands or into the wild.

There is no legal obligation to remove the plant as long as you are not encouraging the spread into neighbouring lands.

If you are using pesticides to treat your knotweed problem, there are some rules set in place for control. You must ensure that you take all of the necessary precautions in order to protect human lives, animal lives, and plant lives.

By law, anyone who is using a pesticide professionally must have the relevant certificate of the safe use of pesticides. They must also be fully trained in the application process of the herbicide.

There are some rules in place regarding off-site disposal of Japanese knotweed. Disposal of Japanese knotweed must be carried out by a licensed waste carrier in a licensed facility. There are transfer notes that must be filled out and stored whenever Japanese knotweed is disposed of in one of these facilities.

In 2013, the UK government brought out new legislation that states that anyone who fails to control Japanese knotweed from spreading could receive and anti-social behavioural order.

This means that failure to control the spread of Japanese knotweed on your land could result in it being seen as a criminal offence. You could be fined up to £20,000 if prosecuted.

Emergency Japanese Knotweed Removal

Japanese knotweed damage can be devastating if left untreated. For people who are selling their homes, it is important that you remove Japanese knotweed before you attempt to sell your home, as this pest could prevent a sale from going through.

An emergency Japanese knotweed removal will usually involve a full excavation and either a burial on-site or removal off-site. This is the fastest method for controlling and removing your Japanese knotweed invasion.

These types of excavation usually cost somewhere between £4000-£20000 for an average-sized garden in the UK. The job will usually take just 1-2 days depending on the extent of growth and the ease of access to your property.

With these methods, it is quite easy to get rid of your Japanese knotweed infestation quickly.

In times of emergency or where you really want to get your Japanese knotweed problem under control and diminished quickly, excavation is the best route and most companies will offer a fast turnaround for this kind of work.

Hiring a Japanese Knotweed Remover

There are a number of things to consider when looking for the right company to carry out work on removing your Japanese knotweed.

Below is a list of things to look out for when choosing the right Japanese knotweed removal contractors for the job:

How much experience does the company have in removing Japanese knotweed?
What methods of removal does the company offer?
What methods of disposal does the company offer?
Does the company offer any guarantees with their work?
What is included in the quote?
Be sure to get at least three quotes so you can ensure you are getting a good price for the job at hand.
Ask for a breakdown of costs in the quote so you can ensure you are getting a good price for each of the different elements of the job.

FAQs

How does Japanese knotweed spread?

Japanese knotweed does not spread via seed dispersion like other types of weed. It spreads through unintentional or deliberate movements of the plant’s chopped stems or fragments of the roots.

Even the smallest part of a Japanese knotweed plant can start new growth. This is why Japanese knotweed is so invasive as it can spread incredibly easily and quickly.

What does Japanese knotweed look like?

In the springtime, purple-reddish coloured shoots begin to emerge from crimson-pink buds that are on the ground level. These shoots grow incredibly quickly and by summertime these large bamboo-like shoots reach up to 7ft tall.

The bamboo-like shoots have noticeable purple spots on them, and they produce branches from nodes all the way along. The leaves that grow off the branches are heart-shaped and grow up to 14cm in length. They also have a noticeable zig-zag pattern along the stems.

The plant will begin to bloom around the end of July and clusters of cream-coloured flowers will begin to show. These flowers can attract a lot of bees. As autumn arrives, the plant dies back, and you are left with brown stems.

Can I Get Rid of Japanese knotweed Myself?

Removing Japanese knotweed can be a very tricky job, especially if there is a lot of knotweed present. It is always recommended that you hire a professional to carry out the removal of Japanese knotweed.

A professional Japanese knotweed contractor will carry out all of the relevant safety precautions as needed in a job like this and they will also have the means to dispose of the waste in an effective manner.

Despite this, if you only have a small amount of Japanese knotweed present, you can carry out a herbicide treatment yourself via the steps above. Glyphosate-based products are best for controlling Japanese knotweed.

The cost of doing a Japanese knotweed treatment yourself is considerably less than if you were to hire a professional to carry out the treatment. However, you do need to be very careful when completing the work.

Is it Against the Law to Have Japanese knotweed on My Property?

It is not against the law to have Japanese knotweed on your property. However, it is against the law to allow your Japanese knotweed to spread onto neighbouring land or into the wild. If you do allow this to happen, you could face some hefty fines.

What is the Quickest Way to Remove Japanese knotweed?

The fasted way to remove Japanese knotweed is through a full excavation. This will involve digging out all of the present knotweed and all of the infested soil.

This waste can then be completely removed and disposed of safely. A complete removal of all of the knotweed will prevent it from ever growing back.