What is Japanese Knotweed?

Japanese Knotweed (Fallopia Japonica) is an invasive and impinging perennial plant that colonises large areas of land with its deep penetrating roots known as rhizomes, it spreads quickly and uncontrollably if it is not treated, and can cause problems for buildings and native woodland species due to the incursive nature of its root system.

The plant was first introduced to the UK in the mid-nineteenth century and was very popular amongst Victorian gardeners due to its fast growth, heart shaped leaves and white flowers. Over time Japanese Knotweed has spread throughout the country through purposeful planting to stabilise loose soil, gardeners sharing cuttings and the unlawful disposal of contaminated garden waste.

Japanese Knotweed is now one of the major environmental issues that faces the UK as the species can grow though tarmac and damage foundations which causes significant structural damage to property and infrastructure. Property and landowners have a legal responsibility to prevent invasive non-native plants, such as Japanese Knotweed from spreading into the wild. This particular species of plant must be removed, treated and disposed of in accordance with current government legislation and the PCA Code of Practice.

How is it identified?

For confirmed identification use a PCA qualified professionals. If you send us a photograph of what you believe to be knotweed and we will give you our professional opinion. See our free service below. If we are unsure, or identify Japanese Knotweed, we would recommend a site survey.


Japanese Knotweed has various tell tale signs. In early spring the plant begins to grow, red buds appear in a cluster just above the ground, growing rapidly throughout the spring and into the early summer, to a height of around two to three meters. At this point the plant has stems comparable to bamboo, which are green in colour, hollow and easy to snap. However, snapping the stems will not eradicate the plant, as new stems will grow in a matter of weeks. As the Knotweed begins to mature, lush green leaves that resemble a heart or shovel type shape begin to grow, up to a size of 20cm across. The leaves have a distinctive straight rear edge and are quite smooth, growing from a characteristic zigzag stem. In the late summer and early autumn, white flowers appear in loose spike like clusters around 10cm long.

knotweed in spring
knotweed in summer


The heart shaped leaves will become darker in colour throughout the summer and will grow in a zigzag pattern on the stem. Towards the end of the summer small clusters of white flowers will start to appear.


The clusters of creamy white flowers grow at the point where the stem joins the leaves. They appear towards the end of August and the beginning of September and can grow up to 10cm long. Towards the end of the autumn the leaves will turn a yellow brown colour and begin to drop.

knotweed in autumn
knotweed in winter


The leaves will all drop and the hollow canes will be left, brown in colour and brittle.

Once Japanese Knotweed is identified it is important you have a professional survey carried out but experts in this field.  At EASTVIEW our qualified surveyors can provide you with this service.

We will carry out a site visit to survey the area undertaking a full initial assessment including checking the boundaries and neighbouring land/properties to determine the extent of growth.

The area that is contractually covered for inspection, monitoring and control should be agreed upon prior to the commencement of work and subsequently marked up on a scaled map within  the survey. This is typically referred to as ‘the Site’.

The site survey report will include:

  • A site plan highlighting areas where the Japanese Knotweed has been identified.
  • Photographs of the Japanese Knotweed in each area as identified.
  • Confirmation as to the spread of the plant onto neighbouring land/property including any historical information relevant, e.g. previous treatments.
  • RICS Assessment. This is an assessment of the risk that this invasive species poses to your property.
  • Full recommendations on treatment option available and what we recommend for your circumstance and budget.

A concerted effort will always be made to determine how well established the Japanese Knotweed on site is. Longstanding infestations with many years of rhizome growth are usually much more difficult to control.

‘Free’ identification service just ask our experts:

If you are still unsure if you have Japanese Knotweed then please click here and upload a photo of the plant in question and one of our experts will feedback to you within 24hrs. If you have any questions then one of the team will be happy to help just call 01782 901074 or 07818 414900 for a free consultation.