Japanese Knotweed

What is Japanese Knotweed

Japanese Knotweed is an aggressive and vigorous growing weed with an extensive root system that can span 7m horizontally and 3m deep. It is highly invasive and will spread very quickly with damaging consequences to properties, infrastructure and biodiversity. 

Where did Japanese Knotweed come from?

Native to Japan, Japanese Knotweed (Reynoutria japonica) grows on the side of volcanoes and is kept at bay by the extreme climate, local fungi and native insects. Brought to the UK as an ornamental plant in 1850, the lack of natural opposition has resulted in rapid colonisation and spread across the country. 

Japanese Knotweed is extremely difficult to get rid of with new plants being able to grow from as little as 2mm of rhizome. You should never try to dig up Japanese Knotweed yourself, specialist knowledge is required to ensure the plant is removed successfully.

Identifying Japanese Knotweed

Stems

Stems are mostly hollow and bamboo-like. They are green in appearance with red/purple speckles. Leaves alternate along the length of the stem producing the characteristic zig-zag pattern.

Leaves

During summer months the leaves are a lush green and heart/spade shape which grows into a point and can reach a length of up to 20cm.

Flowers

The flowers bloom in late summer-early autumn (August/September) and form white/cream coloured clusters that can be 10cm long.

Rhizome (Root)

The rhizome exterior is a dark brown colour and the center core is orange/yellow. Fresh rhizome can be easily snapped.

Damage caused by Japanese Knotweed

The damage caused by Japanese Knotweed can be severe and expensive. Its strong and aggressive roots will force through brickwork, concrete and tar causing structural damage to buildings, foundations, roads and underground pipes. Homeowners may experience a reduction in the value of their property and face challenges in obtaining a mortgage. Contact JBB Knotweed Solutions for complete treatment and removal solutions.

Is it illegal to have Japanese Knotweed on my land?

There is no law against having Japanese Knotweed on your land, however it is illegal to allow Japanese Knotweed to spread onto neighbouring properties or land. If you have Japanese Knotweed on your land you have a legal obligation to prevent its spreading. Failure to do so is an offence and you could be fined. 

Furthermore, there are strict rules on the disposal of Japanese Knotweed and a licensed company such as JBB Knotweed Solutions should be appointed for any offsite disposal requirements.

How to get rid of Japanese Knotweed

There are several approaches used to treat this invasive plant and our qualified surveyors will advise on the best options for you.

Herbicide Treatment

Root barriers

Excavation with off-site disposal

Excavation with on-site treatment

Japanese Knotweed Services

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Stem Injection & Leaf Application

Stem Injection provides a targeted treatment using concentrated doses of herbicide which are injected directly into the plant’s stems using specialised equipment. The herbicide is drawn down through the stem and penetrates deep into the rhizomes where it kills the plant. This method of control is particularly advantageous due to its lower environmental impact.

5. Excavation with offsite disposal (main image)

Excavation and Off-Site
Disposal

Land contaminated with Japanese Knotweed can prove troublesome to developers and construction firms whose projects may be hindered until the knotweed is dealt with. Homeowners looking to build an extension or have their garden landscaped may require an immediate solution.

6. Excavation with onsite treatment

Excavation and On-Site
Treatment

On sites where additional space is available, excavated waste can be stockpiled in a segregated area where its presence will not pose any threat to surrounding structures or be at risk of spreading. A suitable management plan can then be put in place to treat the Japanese Knotweed with herbicide over a period of 2-5 years.

7. Root Barriers

Root Barriers

Root barrier membranes can be used as a means to prevent the spread of Japanese Knotweed onto neighbouring land.  The effectiveness of the membrane is determined by good installation, therefore, it is essential that a specialist contractor such as JBB Knotweed Solutions is involved to undertake the task. A failure to halt Japanese Knotweed from spreading onto neighbouring property could result in legal proceedings.

Book A Survey

We can tell you if you definitely have Japanese

Knotweed on your property and recommend the

best course of action.

We can tell you if you definitely have Japanese Knotweed on your property and recommend the best course of action.