Japanese knotweed (Reynoutria japonica) FAQs

Frequently asked questions about Japanese knotweed for a UK resident:


Comprehensive invasive weed control


Find and tackle problem weeds

Knowledge Hub

Learn about conservation

Japanese Knotweed (Reynoutria japonica)

A highly invasive plant species that has caused headaches for homeowners and landscapers alike.

Japanese Knotweed flowering
Japanese Knotweed growing from shed and paving

Japanese knotweed has tall bamboo-like stems that can grow up to 2m plus tall. The leaves are heart or shovel-shaped and the flowers are small and creamy-white.

It spreads rapidly through its rhizome network. It also spreads through live stem, crown and rhizome fragments that can regenerate into new plants.

This is determined by where it is growing and the conditions of that season but, during the growing season it can grow up to 20cm per day. Its dense stands can reach over 2 metres tall during the growing season.

It can grow in most soil types and a wide range of conditions. It likes moist soil and sunlight but can tolerate shade, drought and high salinity.

Yes, it is persistent and difficult to fully eradicate. Its deep rhizome and root system is hard to fully remove and it can regrow from tiny fragments left behind. However, professional invasive weed companies, such as Conservation Land Services, who fully understand the physiology of Japanese Knotweed and the control options available, are able to easily provide effective control options for Japanese Knotweed.

If there is already an issue or weakness within a structure, actively growing mature Japanese Knotweed can make sue of this opportunity to continue growing past and through the structure, in its search for nutrients. This can then give rise to structural damage.

The presence of Japanese Knotweed on a property can lead to difficulties when selling, buying or refinancing a property. However, once an agreed Japanese Knotweed management plan is in place, this will often satisfy any concerns the mortgage company may have.

It is not illegal to have knotweed on your land, but you are legally required to prevent its spread beyond your boundary under the Wildlife and Countryside Act 1981.

Above ground growth dies back in winter, but the underground roots/rhizomes remain alive and will reshoot the next spring.

It is not poisonous, but has the potential to quickly outcompete and outgrow all native flora, creating a monotypic (nothing else growing) environment, severely reducing the bio-diversity of an area and within residential settings, severely reducing the amenity value of a garden. Where there is already a weakness within a structure, the presence of Japanese Knotweed can present the possibility of further structural damage, if the Japanese Knotweed gains access through the already present weakness.

Featured Videos

Uncover the Secrets of Invasive Weeds

Subscribe to our YouTube channel for expert insights and practical tips on identifying and managing these relentless plant invaders

More from the Knowledge Hub

Japanese Knotweed in flower
Environmental Impact

How Japanese Knotweed Impacts Biodiversity

Contents Introduction Japanese Knotweed (Fallopia japonica) is an invasive plant species that poses a significant threat to biodiversity in the United Kingdom. Originally introduced as ...
Read More →
Japanese Knotweed

Investigation into Japanese Knotweed Spread in the UK

Japanese knotweed (Fallopia japonica) poses a major threat to urban areas in Britain. This invasive plant, native to Asia, has proven extremely adept at colonising ...
Read More →
Japanese Knotweed Versus Russian Vine
Common problems

Can’t Tell the Difference Between Japanese Knotweed and Russian Vine?

Understanding the Similarities Between Japanese Knotweed and Russian Vine Japanese knotweed and Russian vine are two invasive plant species that can often be confused due ...
Read More →
Japanese Knotweed
Common problems

Is Japanese Knotweed in Your Neighbour’s Garden?

Japanese Knotweed, a notorious invasive plant, has become a significant concern in the UK due to its potential to wreak havoc on properties and biodiversity. ...
Read More →
Japanese Knotweed Winter Management video
Commercial Sector

Tackling Japanese Knotweed Infestations in Winter

Japanese knotweed is a notoriously aggressive invasive plant that can be extremely difficult to eradicate once established. This resilient perennial spreads voraciously, making it a ...
Read More →
Japanese Knotweed left unmanaged
Indemnity insurance

Do You Need Indemnity Insurance for Japanese Knotweed?

Japanese knotweed, a name that strikes fear into the hearts of homeowners and property buyers alike. This seemingly innocuous plant, with its bamboo-like stems and ...
Read More →

Free Consultation

Book an appointment for a call back.

Japanese Knotweed
Giant Hogweed
Himalayan Balsam
Hemlock Water Dropwort