Why is Japanese Knotweed Such a Big Problem?[2023]

Exploring the Impact and Risks of This Invasive Species

Discover the reasons behind the notorious reputation of Japanese Knotweed. This non-native plant species are causing significant damage to properties, wildlife habitats, and ecosystems.

Japanese Knotweed is a highly invasive plant species that is causing a significant problem across the UK and other parts of the world. This plant, which originates from East Asia, was introduced to the UK in the 19th century as an ornamental plant. However, it has quickly become one of the most destructive and problematic invasive plant species. Due to its aggressive growth, resistance to control measures, and ability to cause damage to buildings, infrastructure, and the environment. In this article, we will explore why Japanese Knotweed is such a big problem, and the risks and impact it poses to our surroundings.

What is Japanese Knotweed?

Japanese Knotweed, or Fallopia japonica, is a fast-growing, herbaceous perennial plant that can grow up to 10cm per day in the summer months. It is characterized by its bamboo-like stems, heart-shaped leaves, and clusters of white flowers. Japanese Knotweed can grow up to 3-4 meters tall and can spread quickly through rhizomes, and underground stems that can grow up to 7 meters in length. Rhizomes can also survive for up to 20 years, which makes controlling the plant extremely difficult.

Why is Japanese Knotweed such a big problem?

  1. Property Damage

One of the most significant risks associated with Japanese Knotweed is the damage it can cause to properties. The plant’s rhizomes can grow through foundations, walls, and pipes, causing damage to buildings and infrastructure. This can lead to costly repairs and, in severe cases, can make properties uninhabitable. Due to the significant impact on property values, the presence of Japanese Knotweed can also affect property transactions and mortgage applications.

  1. Ecological Damage

Japanese Knotweed can also cause significant damage to ecosystems by outcompeting native plants for resources, reducing biodiversity, and altering habitats. The plant’s fast growth and dense foliage can create a canopy that shades out other plants, preventing them from growing. As a result, wildlife habitats can be destroyed, and species that depend on those habitats can be negatively impacted.

  1. Legal Risks

The presence of Japanese Knotweed on private or public land can also lead to legal risks. Under UK law, it is illegal to plant or cause Japanese Knotweed to grow in the wild. It is also the responsibility of landowners to control the spread of the plant and prevent it from causing damage to neighboring properties. Failure to do so can result in fines and legal action.

  1. Difficulty in Eradication

Due to its invasive nature and the resilience of its rhizomes, Japanese Knotweed can be challenging to eradicate. Traditional control measures, such as cutting and chemical treatments, are often ineffective and can even exacerbate the problem by spreading the plant further. This means that controlling Japanese Knotweed can be time-consuming and costly, often requiring specialist expertise and equipment.


Q: Is Japanese Knotweed poisonous? A: Japanese Knotweed is not poisonous to humans or animals. However, it can cause damage to buildings and infrastructure and hurts ecosystems and biodiversity.

Q: Can Japanese Knotweed be removed by cutting it down? A: Cutting Japanese Knotweed can help to reduce the size of the plant and make it easier to control. However, cutting alone is not enough to eradicate the plant as it can regrow from rhizomes left in the soil.

Q: Can Japanese Knotweed be composted? A: Japanese Knotweed should not be composted or disposed of in the regular garden waste

Ways to Control Japanese Knotweed
  1. Chemical Treatments

Chemical treatments are one of the most effective ways of controlling Japanese Knotweed. Glyphosate is a commonly used herbicide that can be used to kill the plant. However, specialist equipment and knowledge are required to ensure the chemical is used safely and effectively.

  1. Physical Removal

Physical removal of Japanese Knotweed involves excavating the soil and removing the rhizomes. This method is often used in areas where chemical treatments are not appropriate or when the risk of damage to the environment is high. However, this method can be costly and disruptive, and care must be taken to ensure all rhizomes are removed.

  1. Combination Approach

A combination approach, using a combination of chemical treatments and physical removal, can often be the most effective way to control Japanese Knotweed. This approach can help to reduce the number of chemical treatments required, minimize the risk of damage to the environment, and ensure the plant is eradicated.


In conclusion, Japanese Knotweed is a significant problem due to its aggressive growth, resilience to control measures, and the damage it can cause to properties, wildlife habitats, and ecosystems. As a non-native species, Japanese Knotweed has no natural predators in the UK, and without effective control measures, it can continue to spread and cause damage. It is essential to take Japanese Knotweed seriously and seek professional advice if you suspect it is present on your property or land. Effective control measures can help to eradicate the plant and minimize the risk of damage to your surroundings.

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