Japanese Knotweed (Fallopia Japonica)
Everything you need to know about Japanese Knotweed
What is Japanese Knotweed (Fallopia Japonica)?
Japanese knotweed (Fallopia japonica) is a non-native invasive weed that is known for it’s fast-spreading and destructive nature.
The species is recognised by its bamboo-like stems, spade-shaped leaves (up to 14cm (5½″) in length), and creamy white flowers in the summer.
Japanese knotweed has expansive root systems (rhizomes) that can develop up to 3m (10ft) deep, and leave the exposed weed to grow up to 2.1m (7ft) tall.
It is extremely hard to eradicate without professional help, and there are laws around its encroachment and its disposal.
Habitats
Japanese knotweed can exist in most habitats, including river banks, woodlands, grasslands and coastal areas – most notably, waysides, borders and pavements.
How did Japanese knotweed get here?
Native to Japan, Korea and parts of East Asia and China, historical information shows us that Japanese knotweed was brought to the UK by a German-born botanist, Philipp von Siebold in 1850. This was during a wave of popularity surging through Victorian Britain to collect and study plants from across the world.
Japanese knotweed flowers and foliage were used for animal fodder and, at first, prized for their beauty—so much so, that in 1847, the species was named as ‘the most interesting new ornamental plant of the year,’ by the Society of Agriculture and Horticulture in Utrecht.
Inevitably, the interest in Japanese knotweed quickly evolved into, ‘How on earth can we get rid of it?’ because it proved to be a ferocious, invasive and destructive plant. In its natural habitat, on the side of volcanoes, the extreme climate, deposits of volcanic ash, native fungi and insects limited its spread, but in Britain, there are no such natural regulators or predators.
Japanese Knotweed Appearance
Throughout the year, knotweed looks different, and differentiating it from other plants can be tricky. Identifying knotweed does require a professional survey, and in winter, a dog detection survey helps to find dormant knotweed that isn’t flowering.
There are a number of plants commonly mistaken for Japanese knotweed, including:
- Bindweed
- Himalayan Balsam
- Bamboo
- Broad-leaved Dock
- Himalayan Knotweed
- Himalayan Honeysuckle
- Russian Vine
- Lilac and Woody Shrubs
Japanese knotweed in spring:
- The first signs of Japanese knotweed growth, Usually the early signs of growth are seen in mid-March
- Distinctive red and purple shoots – often accompanied by rolled back leaves which grow rapidly from the stored nutrients in the rhizome.
Japanese knotweed in summer:
- The stem resembles bamboo, though greener in colour with purple speckles.
- Inside the cane are distinctive chambers that retain water and nutrients.
- The leaves are large and have pointed tips that extend from the stem in a zig-zag pattern.
- Later in the season creamy-white flowers hang in clusters from the stalks.
Japanese knotweed in autumn:
- Bamboo stems turning a darker brown with a lot of foliage.
- The leaves are large and have a heart shape with pointed tips that extends from the stem in a zig-zag pattern.
- The leaves will be wilting and beginning to turn yellow.
Japanese knotweed in winter:
- As the first frosts appear the plants leaves turn brown and the plant withdraws back into its rhizome.
- The canes lose their colour and turn into woody stalks, which can take years to decompose.
- New shoots can be found growing through the dead canes in the early Spring.
What Does Japanese Knotweed Do?
Japanese knotweed is one of the biggest plant threats around; it’s highly invasive, and thanks to its quick-spreading root systems, it can overwhelmingly take over a space with ease. Some of the biggest issues with Japanese Knotweed is that it:
Costs the UK economy millions in damages
Spreads rapidly, making it harder to control
Grows at a rate of up to 20cm a day, causing infestations to spread
Threatens building foundations, leading to costly property damages
Breaks through concrete and other hard items
Even the tiniest fragment left behind that can regrow and haunt a property
Makes buying & selling difficult
Has a reputation for being incredibly hard to fully eradicate
Laws and Responsibilities
There are currently multiple laws concerning Japanese knotweed, including:
- EA (Environment Agency) Knotweed Code of Practice
- PCA (Property Care Association) Code of Practice
- Invasive Weed ASBO: The Anti-social Behaviour, Crime and Policing Act 2014
- Wildlife and Countryside Act 1981
- The Environment Protection Act 1990
Some laws are specific to certain areas, such as development sites or disposal, but others cover much wider areas such as the spread of knotweed to neighbouring land and the care needed to prevent that.
When it comes to buying and selling property, whether you’re buying, selling, or re-mortgaging, Japanese knotweed can have serious implications on these processes. For those looking to buy or sell homes from March 2022 onwards, there is new guidance from RICS (The Royal Institute of Chartered Surveyors) on the management and categorisation of Japanese knotweed.
A seller’s responsibilities
It is your responsibility to check that Japanese knotweed is not present on your property if you are looking to sell your home.
When filling out the TA6 form, you will be asked to confirm whether the property has Japanese knotweed present or not. As of 2020, the question surrounding Japanese knotweed prevalence was revised, and now you are only able to state that there is no Japanese knotweed within 3 metres of the property if you are entirely certain.
Where it is present, you must provide a management plan for its eradication from a professional company like Japanese Knotweed Specialists.
A buyer’s responsibilities
If Japanese knotweed is known to be present at the property you are purchasing, it will be stated in the TA6 form. This will then result in your mortgage lender requiring assurance that it’s eradicated before lending. Having a management plan in place from professionals like Japanese Knotweed Specialists, backed by a transferable guarantee, is usually the assurance they require.
Japanese Knotweed and Property
Speak to the experts and eradicate the plant before it spreads to avoid it entering neighbouring properties and land – It’s your responsibility to arrange for removal and treatment as a landowner, and to prevent the spread onto neighbouring land.
A smaller infestation can be stopped quicker than a large one. However, regardless of the size of the spread, knotweed must be eradicated, as the root system can spread quickly underground.
Japanese Knotweed Specialists offer:
- Removal on sites from 1m2 to over 1000m2
- Both commercial and residential removal performed by accredited experts
- Surveys, both dog and human, to understand the extent of the problem
- Sifting and screening for rhizomes
- On-site burial or relocation with herbicide treatments
- Off-site removal with accredited waste licences
- Insurance-backed guarantees between five and 35 years
Our eradication methods are fully compliant with all current relevant regulations and carried out carefully to minimise risks to waterways, local environments and other plant species.
Contact us
With a number of different removal and treatment options available,
please call our specialist knotweed removal team on 0800 122 3326 for advice or send us an enquiry.
