Japanese Knotweed is a notoriously difficult plant to manage due to its fast growth and invasive nature.
Cutting down Japanese Knotweed is one of the most effective methods of control, but it must be done correctly to prevent the plant from regrowing and spreading.
In this blog post, we’ll explore the best methods for cutting down Japanese Knotweed and provide tips on how to do it effectively.
Japanese Knotweed is one of the most invasive plants in the world and can cause significant damage to buildings and infrastructure.
The Royal Horticultural Society
Why Cutting Down Japanese Knotweed is Important
Japanese Knotweed is one of the most invasive plants in the world and can cause significant damage to buildings and infrastructure. Cutting down Japanese Knotweed is an essential part of controlling its growth and preventing it from causing further damage or spreading to new areas.
Cutting down Japanese Knotweed is important for a number of reasons. Not only does it help prevent the further spread of the plant, but it also helps reduce potential damage caused by its roots which can weaken foundations, walls and other structures over time. It can also help keep gardens free from knotweed as well as prevent any potential health risks associated with contact with the plant’s sap or leaves.

Effective Cutting-Down Methods
There are four main methods of cutting down Japanese Knotweed, which include mechanical cutting, chemical treatment, stem injection and burning. Each method has its own advantages and disadvantages and should be used in combination for the most effective results.
Mechanical Cutting
Mechanical cutting is a physical removal method that involves manually hacking the knotweed down with tools such as a machete, saw or hedge trimmer. This method requires regular maintenance and is best for small patches of Japanese Knotweed.
One advantage of mechanical cutting is that it is more cost-effective compared to other removal methods, such as chemical herbicides. Additionally, this method does not require the use of any chemicals, which makes it more environmentally friendly. Finally, mechanical cutting is fast and can be done with minimal effort.
The major disadvantage of this method is that it requires regular maintenance and is best for small patches of knotweed. If the patch of knotweed is too large, mechanical cutting can be labour-intensive and time-consuming.
If the cuttings are not disposed of properly they may still spread and regrow elsewhere in the area. Finally, this method does not guarantee complete eradication of the knotweed, as some pieces may remain and regrow.
Because of its advantages and disadvantages, mechanical cutting is best used for small patches of Japanese Knotweed that can be maintained easily. When using this method, it is important to properly dispose of cuttings so as not to spread the knotweed to other areas.
This method must be used in conjunction with other methods such as chemical spraying or digging out for complete eradication of the knotweed.

Chemical Treatment
Chemical treatment involves applying a herbicide directly to the foliage of the plant to kill it off. This method is best used when dealing with large areas of knotweed and is relatively cost-effective.
The use of chemical treatment to eliminate knotweed is a relatively cost-effective solution to a potentially pervasive problem. It is particularly useful for large areas that are infested, as it does not require the person applying it to physically remove each weed. One advantage of this method is that it can be done at any time during the growing cycle and is relatively quick and easy.
However, chemical treatment does have some drawbacks. The herbicide will kill any plants that are growing in the area, including desirable vegetation.
Additionally, knotweed can become resistant to certain herbicides over time which means that multiple treatments may be necessary to completely eradicate the weed. Finally, it’s important to note that herbicides can have negative impacts on the environment, so it’s important to use them carefully and in accordance with applicable regulations.
In conclusion, chemical treatment is a cost-effective and relatively easy way to deal with knotweed infestations. It is best used when dealing with large areas of knotweed that cannot be physically removed. However, it can harm desirable plant life in the area and may require multiple treatments to be effective. Care should be taken when using herbicides as they can have negative environmental consequences.

Stem Injection
Stem injection involves injecting a herbicide directly into the plant’s stem. It is most effective for large infestations and can be used in combination with other methods for maximum control.
The advantages of stem injection are that it is particularly effective against large infestations, and when used in combination with other methods, it can provide maximum control. This method of weed control also reduces the amount of herbicide needed to treat an area since it is only being injected directly into the plant’s stem.
For example, compared to using a broadcast spray across the entire area, stem injection can reduce herbicide use by up to 60%.
The disadvantages of stem injection include the cost of equipment and labour. Stem injection requires specialized equipment for each weed species that needs treating, as well as a trained professional to do the job properly. Additionally, this method may cause physical damage to nearby plants, as the injected herbicide can spread to other parts of the plant.
Overall, stem injection is an effective method of weed control for large areas and when used in combination with other methods, it can provide maximum control.
However, this method does require specialized equipment and labour which may make it cost-prohibitive for some. Additionally, this method may cause physical damage to nearby plants. It is important to consider the pros and cons of stem injection before deciding on a weed control strategy.

Burning
Burning Japanese Knotweed is another method of cutting it down, however, this should only be used as a last resort due to the potential for dangerous smoke and fumes. It’s also important to ensure that all parts of the plant are burned which can be difficult to achieve.
Burning Japanese Knotweed is a method of cutting the plant down but it should only be used as a last resort due to potential health risks associated with the smoke and fumes emitted. One advantage of this method is that it eliminates the entire plant in one go, without multiple applications or treatments required.
However, there are several disadvantages associated with burning Japanese Knotweed. Firstly, it’s difficult to ensure that all parts of the plant are burned completely – incomplete burning can lead to regrowth from root fragments. Burning can also result in smoke containing potentially carcinogenic compounds being released into the environment, so extra care should be taken when using this method. Additionally, burning is usually illegal and requires a permit from the local authorities.
In conclusion, burning Japanese Knotweed should only be used as a last resort due to the potential health and environmental risks associated with it. Before using this method, it’s important to ensure that you have the necessary permits and take all necessary precautions to protect yourself and your property.
Tips for Effective Cutting Down
- Before starting any cutting-down project, it’s important to put on the appropriate safety gear such as safety glasses and gloves.
- Make sure that all parts of the plant are cut down – this includes roots and rhizomes which can still regrow if left intact.
- Dispose of all cut-down knotweed in a responsible manner. This could include burning, burying or disposing of the plant material at an approved landfill site.
- Monitor the area regularly to ensure that the Japanese Knotweed does not return.
Final thoughts
Cutting down Japanese Knotweed is an essential part of controlling its growth and preventing it from causing damage to buildings and infrastructure. By using the best methods for cutting down Japanese Knotweed and doing it effectively, we can prevent the plant from spreading and protect our built and natural environments.
If you’re unsure of the best method to use for cutting down Japanese Knotweed on your property, don’t hesitate to contact a qualified professional for assistance.