Do I have Japanese Knotweed? | Green Leaf Remediation

Do I have Japanese Knotweed discussed by SW Knotweed Removal Specialists

Thinking or worrying you may have Japanese Knotweed on your property is not good and it is really easy for a specialist Japanese Knotweed Company to come out and quickly establish if you do and what you should do.

Japanese Knotweed is tricky to identify if you don’t have the experience as its appearance changes over the seasons and can quite often be mistaken for other perennial plants or weeds.

Japanese Knotweed, also referred to as Fallopia Japonica, Bamboo or Peashooters was originally brought into the UK in the mid 18th century by a German-born botanist named Philipp Von Siebold. Philipp found it growing on the side of a volcano in eastern Asia and brought it to the UK for it to be used as an ornamental plant in residential and commercial gardens. In 1854 Philipp sent a shipment of various plants, included Japanese Knotweed to the Royal Botanic Gardens in Kew where it was planted The shipment was also sent to the Royal Botanic Gardens in Edinburgh and was sold by nurseries to homeowners and commercial property owners and this is when it started to spread across the UK.

Japanese knotweed is found all over the UK and surprisingly it is most common in urban areas, although it is also often found on wasteland, railways, roadsides and river banks.

How do know if you have Knotweed on your property?

Japanese knotweed leaves are identified by their shovel-shaped or heart-shaped leaves. They have a point at the tip and are staggered on the stem, with one stem per node which creates a zig-zag stem growth pattern. They are a bright and rich green colour and can grow up to 20cm long.

Japanese knotweed flowers are long clusters of creamy white flowers which appear towards the end of summer early September. The clusters can grow to around 0.5cm wide and up to 10cm long. The leaves remain as they are as the flowers grow which result in thick, dense foliage.

Japanese knotweed rhizomes are the root part of the plant which grow extensively and quickly underground. The outside of the stem is dark brown and the inside is orange/yellow. The fresh stems will be crisp and will snap easily when bent. The rhizomes can grow up to 3 metres in-depth and up to 7 metres horizontally from the plant and is how it is most likely to spread from just one tiny fragment, as little as 0.7g can create a new knotweed plant.

Japanese knotweed stems can grow up to 2 – 3 metres tall, sometimes more and they are similar to Bamboo hence why it is often referred to as bamboo. They can grow 10cm a day and 20cm at its most prolific. They have nodes and purple speckles and the leaves grow outwards from the nodes in a zig-zag type pattern. As the weed matures the stems inside become hollow making them easy to snap in two and during the winter the stems become very brittle.

Japanese Knotweed is a perennial plant and its appearance changes with the seasons:

Japanese knotweed in Spring

Japanese knotweed grows fastest during springtime and can reach 3 plus metres high. Its new shoots emerge with a red/purple tinge and are often referred to as looking like asparagus spears. The leaves normally roll up and are dark green or tinged with red.

Japanese Knotweed in Summer

By early summer, the plant is fully grown and reaches over 3 metres tall and by late summer clusters of creamy white flowers will appear.

Japanese knotweed in Autumn

In Autumn the leaves start to turn yellow and will wilt, however, the density of its leaves remain. It can still be over 3 metres high and the hollow stems start to turn brown.

Japanese knotweed in Winter

At the beginning of winter, the knotweed canes will die off, it is still very much alive just isn’t actively growing. The leaves will change to a yellow colour, then into brown and fall off. The hollow canes become dark brown and brittle and they give way against each other, falling to the ground. In springtime, as the weed starts to actively grow again, you will see the previous year’s canes lying underneath the foliage.

Important Knotweed Facts

If you have grazing animals, Japanese knotweed can be safely eaten by sheep, cattle, horses, and goats.

If you think you have Japanese Knotweed do not cut it back or dig it up as it spreads quickly and aggressively over and underground and makes it more difficult to manage. It is an offence to plant, disperse, allow dispersal or cause the spread of invasive plant species which applies to Japanse Knotweed. Always contact a Knotweed specialist who will come out to your property, identify if it is Japanese Knotweed and advise you of the best treatment and control method which they will be legally qualified to carry out.

Removing Japanese Knotweed yourself is possible, however, it is extremely difficult to control and prevent it from spreading, and more often than not doing it without a Japanese Knotweed specialist and the right herbicidal treatments will result in it growing back and spreading further over and underground.

Spraying with chemicals is an effective treatment to stop Japanese Knotweed spreading, however, you must only use approved herbicides which you will normally need a qualified specialist to use. It can take anything from 3 – 5 years to effectively treat and control Japanese knotweed to ensure the underground rhizomes, which spread quickly from a tiny fragment become dormant. Knotweed can be eradicated immediately through an excavation process which involves digging it up from its roots, however, there is a huge amount of legal legislation around this process and you should always use a qualified Japnese Knotweed specialist. Japanese knotweed is classed as “controlled waste” under the Environmental Protection Act 1990, which means it has to be meticulously removed and taken to a licensed landfill site by a qualified specialist which is costly.

You should not dispose of Japanese Knotweed yourself and under no circumstances dispose of it in your compost, recycling, or waste bins, due to its ability to spread quickly from just one tiny fragment.

There is no legal obligation to remove or treat knotweed as long as you are not encouraging or allowing it to grow onto any adjacent land. Schedule 9 of the ‘Wildlife and Countryside Act 1981’ states; you must not plant or cause to grow Japanese Knotweed in the wild.

If Japanese Knotweed is allowed to spread onto your land then you can issue private nuisance proceedings in the Civil Courts for:

  1. damages for loss of enjoyment and diminution of value of a property
  2. the costs of removal
  3. an injunction against re-infestation

In addition to this, Local Authorities have the power to serve notice on an occupier of land which has Japanese Knotweed growing. The notice can require the landowner to remedy any knotweed which could adversely affect the amenity of an area within a set period, and failure to do this or failure to safely and properly dispose of the knotweed can lead to criminal liabilities.

When Japanese knotweed is identified on a property, mortgage providers will often refuse to lend if a specialist knotweed management plan is not in place as it is an unacceptable risk to lenders due to the high risk of it spreading on your property, others around you, as well as aggressively growing through cracks and weak spots in foundations and brickwork as it searches for light and water, often damaging a structure and causing significant damage if not properly controlled and removed.

As an example, it can easily push its way through a crack in a patio and crack and, or block underground drains and pipework.

Japanese Knotweed can cause subsidence if your property has weak areas, to begin with, as the strong and fast-growing roots cause extensive ground movement resulting in soil shifting.

However, It is a myth that knotweed can grow through solid concrete.

It can grow 10cm a day (20cm at its most prolific) and in just 10 weeks in the height of its growing season, its stem can reach 3 plus metres high. Underground, the rhizomes roots also growing quickly and can spread up to 7 metres horizontally and 3 metres deep.

The best time to chemically treat Japanese Knotweed is in the summer when it is flowering and the foliage is taking the most nutrients to its roots.

It is highly recommended that you use a professional and Japanese Knotweed specialist to ensure it doesn’t spread and grow back. A professional will identify the knotweed and determine the extent of it to offer a licensed and qualified management plan to ensure effective and safe removal, as well as reducing the chances of it spreading and regrowing.

Japanese Knotweed is often seen as an attractive plant which is why it was originally brought to the UK and its appearance changes through the seasons including:

  • Fleshy, red/orange-tinged shoots
  • Large heart-shaped or spade-shaped leaves
  • Leaves forming in a zig-zag pattern along the stem
  • A hollow-like stem that looks like bamboo
  • Fast-growing tall stems with lots of green leaves
  • Clusters of cream flowers in the summer
  • Bare stems that don’t die off in the winter when it becomes dormant

What should you do if you think you may have Japanese Knotweed?

If you think you may have Japanese Knotweed you should contact a qualified Japanese Knotweed expert as it is your legal responsibility to control it and if you don’t,
you could be at risk of fines and legal claims against you if it spreads to any neighbouring properties.

South Wales Knotweed Specialists

South Wales Knotweed Specialists covers the whole of South Wales (including Swansea, Cardiff and Newport), West Wales up to North Ceredigion & Powys and throughout South Glamorgan & Gwent & Tenby. We carry out contracts in the West Country, as far North as Shropshire and into the Midlands & Birmingham areas.

We are a fully qualified Japanese Knotweed Certificated Surveyor (JKCS) and we specialise in controlling Japanese Knotweed, other invasive plants and ‘general nuisance weeds’ which are found in the UK for residential and property development sites.

We also provide tree services, such as pollarding, crowning, pruning, felling, through our NPTC chainsaw operators, all of whom possess a vast amount of experience in the forestry industry.

Our Qualifications & Accreditations
  • City & Guilds NPTC Level 2
  • Principles of Safe Handling & Application of Pesticides (PA1/PA6)
  • Principles of Safe Handling & Application of Pesticides near water (PA6AW)
  • Herbicide Stem Injection
  • Property Care Association
  • The Control & Eradication of Japanese Knotweed Surveyor’s Training Course
  • Qualified Technician (PCAQT) in Japanese Knotweed
  • Accredited Surveyor in Japanese Knotweed

There are varying methods of removing and controlling Japanese Knotweed and we will give you advice about the best and most effective method for your property.

Stem-Injection is a low impact way of removal and there is little risk of disturbing or killing the plants and flowers growing close to it. The stem-injection technique is normally used for smaller areas of Knotweed where it has established itself among plants and vegetation that you would like to maintain. Additionally, it is an approach generally applied when Knotweed is near a watercourse. The stem-injection approach can be used in dry or inclement weather conditions and the soil can’t be disturbed following a treatment.

Foliar Spray Application is frequently used and is amongst the most favourable control methods as well as stem-injection. The method is used to manage the Knotweed over several growing seasons. Dependent on the size of the area of Knotweed is it is normally sprayed 2-3 times in the first year and once in the subsequent years. The chemical used is an Environment Agency approved herbicide and needs dry weather conditions as well as the soil to remain undisturbed in subsequent years to work.

Weed Wiping Method is the when leaves of the plant are wiped with a sponge that is soaked with the required herbicide. It’s a low impact treatment and does not kill or disturb the foliage adjoining it, even so, its use depends upon the size of the area of knotweed.

Bund/Stockpiling Method is a blended treatment method using stem-injection and foliar application, followed by excavating the underground material and removing the soil and material to a different location in which the emergence of ‘new shoots’ can be subjected to additional herbicide application. This process is used on sites where you need the removal of the knotweed to be fast and not done over several seasons so is consequently particularly beneficial to building plots of land and development sites as work can proceed without delay.

Cell Burial/Root Barrier Method is a treatment used when there is enough space on-site to create a cell burial or making use of a root barrier to avert the considerable expenses of transporting the soil and waste to landfill. Cell burial buries the Knotweed waste to a minimum depth, or if encapsulated inside a geomembrane it can be closer to the surface of the ground. Root barriers can be installed both vertically and horizontally when there is a danger of cross-boundary contamination. Again, a method most often used on development sites when construction work needs to start promptly.

Excavation & Removal Off-Site is a legitimate and swift control option which has its advantages for development sites if performed correctly, however, a lot of Knotweed Professionals are not advocates of it, simply because it raises considerable logistical problems. The challenges being there is an extremely high risk of the Knotweed spreading, as well as the cost to securely transport the material to a designated landfill site. There is also a considerable duty of care requirements under the Environmental Protection Act (EPA) 1990. In conclusion, Excavation & Removal should only be used as an absolute last measure.

If you have or think you might have Japanese Knotweed then contact us today on 01269 591651 and one of our specialists will answer any questions you may have and can arrange for us to come out to your property to identify if you have it growing, assess the extent of it and advise you of the best removal and control method.