General
What is Japanese knotweed?
Japanese knotweed is an invasive, herbaceous perennial plant in the buckwheat family, known for its rapid growth. Characterised by its stout stems and heart-shaped green leaves, it can grow up to 3 metres tall. Japanese knotweed is an aggressive plant that produces a high number of seeds which can be easily spread by animals.
The Environment Agency deems Japanese knotweed to be the most common of 4 invasive knotweed plant species in the UK. Left unchecked, Japanese knotweed can quickly take over an area, crowding out native plants and disrupting ecosystem balance.
Do you have to report Japanese knotweed?
You should report Japanese knotweed to the Council if you find it growing on council land or if it has encroached onto your property. However, it is not an offence to have Japanese knotweed on your land, so you do not legally need to report it if it is not causing a nuisance.
While it is not illegal to have it on your land, you do have legal responsibilities, for example, if it encroaches on a neighbouring property. Find more information about the legalities surrounding Japanese knotweed here.
Portsmouth County Council has all the information you need for reporting Japanese knotweed. This helps experts like ourselves to address the problem effectively and reduce its further spreading within the community.
How harmful is Japanese knotweed?
Japanese knotweed can be incredibly harmful to both residential and commercial properties, as well as ecosystems and biodiversity. It outgrows native plants, which can have a negative impact on biodiversity and can grow through cracks in concrete and therefore hugely damage buildings and other infrastructure.
Identification
How do you Identify Japanese knotweed?
Japanese knotweed can be identified by the following characteristics:
Height: It can grow up to 3 metres tall
Leaves: Heart-shaped, glossy, green leaves
Stems: Hollow with nodes about 10cm apart
Nodes: With small, branching roots at 5-10mm in diameter
Internodes: Dark purple or reddish brown with a smooth surface
White Flowers
If you think you’ve found Japanese knotweed on your property, get in touch with our team today.
How quickly does Japanese knotweed grow?
Japanese knotweed begins growing in early spring and can thrive in any soil type. It grows rapidly, up to 20 cm per day, reaching about 1.5 metres by May and up to 3 metres by June.
Learn more about Japanese knotweed’s growth patterns here.
Where can Japanese knotweed be found?
Japanese knotweed can be found anywhere, including along roadsides, railways, riverbanks, streams, gardens, woodlands and in residential and commercial properties. It can cause significant damage to buildings and infrastructure by growing through foundations, walls, and floors. It can also invade gardens and lawns, disrupting biodiversity and outgrowing other plants.
How does Japanese knotweed spread?
Japanese knotweed is spread by fragments of rhizome or stem being transported to new areas. This can be spread by humans moving rhizome fragments from a contaminated area, for example on shoes, tools and gardening equipment. It can also spread naturally where fragments of the plant are transported on animal fur or in their paws.
Removal
Why do I need to remove Japanese knotweed?
It’s important to remove Japanese knotweed because it is a highly invasive plant which can have a detrimental impact on buildings and ecosystems. Neighbours can also take legal action against you if it spreads from your property to their property.
Can I remove Japanese knotweed myself?
Once Japanese knotweed becomes established on a property, it is extremely difficult to control or remove without professional help. To ensure complete removal, it’s best to contact specialist removal contractors for a site survey.
It is crucial that you DO NOT cut or trim Japanese knotweed, as it can cause mass cross-contamination. If even a fragment of the plant enters another patch of soil in your garden, then it can easily regrow.
How much does Japanese knotweed removal cost?
Japanese knotweed removal in the UK can cost anywhere between £500-£50,000+ depending on scale and complexity. To find out more, we recommend booking a site survey to assess the extent of the infestation.
