Untangling the Truth about Japanese Knotweed

Property maintenance and house buying or selling can all be problematic, but just when you thought it couldn’t get worse, Japanese Knotweed appears – along with the potential to put you in prison! What do you need to know?

Where it came from

Also known as Japanese Bamboo or by its botanical name of Fallopia japonica, Japanese Knotweed is an invasive plant with bamboo-like stems. Originating from Japan, northern China and Taiwan, the plant was purposely introduced to the UK in the early 19^th century. Although intended as an ornamental plant, it quickly became common across the UK as a persistent wild plant, with many problems stemming from its root-like stems (rhizomes) which can grow prolifically up to 3m underground as well as across soil and property.

Why not Knotweed?

Japanese Knotweed’s prolific and pervasive growth of up to 20cm per day have caused the plant to become infamous across the UK for causing problems:

• Its abundant growth can inhibit and destroy other native plants;

• Invasive growth on river banks can contribute to erosion and increase the possibility of flooding in localised areas;

• Persistent and underground growth can cause structural problems to property, paving, asphalt, watercourses and other ground or wall surfaces.

The effects of these problems can be extremely expensive, particularly if the plant is not dealt with properly or promptly. Many property owners have struggled with structural damage to their properties, which itself can cause additional problems:

• Expensive repairs as insurance companies increasingly identify Japanese Knotweed damage as a problem which is not covered by standard property buildings insurance policies (source: Royal Institution of Chartered Surveyors);

• An increasing number of mortgage lenders refusing loans on properties affected by Japanese Knotweed, causing sales to fall through;

• Properties losing a considerable amount of their potential value, once a problem with the plant is identified locally;

• Litigation, and even prosecution under anti-social behaviour legislation, in cases where an individual is considered to be responsible for the spread of Japanese Knotweed, for example where there has been a failure to eradicate the plant, causing spread and damage to a neighbouring property;

• Litigation and prosecution if the presence (or removal) of Japanese Knotweed is not declared when selling a property.

Knowing your Knotweed

It’s imperative to be able to identify Japanese Knotweed quickly. The appearance of a random growth in a garden or within a building’s structure or grounds should always be investigated. Identifying features of Japanese Knotweed include:

• A reddish tinge to any shoots coming through the ground;

• Large, flat heart / spade shaped leaves;

• Leaves which grow at regular, zig zag intervals along a stem;

• A stem which is hollow, just like bamboo;

• Cream flowers which grow in clusters on the plant during July. Bees are very attracted to these flowers;

• The fact that the plant regularly dies back throughout September, October and November, leaving only brown stems is a key feature.

This dying back of the plant can really give a false sense that the plant is ‘gone’ or has died. In reality, it’s just a hibernation period for the plant and, if left, it will grow back, unabated and more prolifically, the following season. So what should you do?

An overview of options

Since 2010, botanical experts have been experimenting with a Japanese insect, Aphalara Itadori, which has been specifically introduced to the UK as the plant’s only known predator – because its diet is predominantly Japanese Knotweed. It’s not fully known yet what impact this insect would have on the wider UK knotweed problem and what the ecological knock-on effect to native insects might be, so although the signs are hopeful, it is likely to be some time yet before gardeners and property owners can rely on insect support for knotweed removal.

In the meantime, it is possible to dig out the plant, but this requires significant care and is often a large-scale operation as leaving even the smallest section (0.8g minimum) can be enough to permit the plant’s regeneration.

Additionally, the problem doesn’t stop with getting it out of the ground. Because of its classification as a controlled waste item (source: Environmental Protection Act 1990), Japanese Knotweed can only be disposed of:

• At designated, licensed landfill sites, using a licensed waste carrier for transportation, to avoid further spread;

• Through chemical treatments which may take up to five years to be effective and cost several thousands of pounds;

• By drying out every section, then burning it;

• Burying the whole plant at nothing less than 5 meters deep.

These last two methods of disposal tend to be extremely impractical as well as unreliable for most property owners. The Environment Agency require that any burial of the plant needs to be reported to them prior to doing so, as burial is forbidden in some areas and, crucially, this method does not always offer any guarantees that re-growth won’t occur.

Prompt, proper action means professional removal

As a result, an increasing number of property owners are finding that the only way to really eradicate the problem of Japanese Knotweed is by using professional controlled waste disposal services from companies such as Safe Site Facilities, whose professional approach ensures:

• A prompt and pro-active response to enquiries, to help confirm the presence of the plant and to offer advice and professional solutions, depending on the spread and conditions of the growth;

• UK-wide coverage;

• Experience and professional removal and disposal;

• Individual solutions to fit every situation, as the spread of the plant can affect both property and grounds;

• Fully licensed for transportation and disposal of the plant;

• Guarantees and full insurance, crucial when it comes to selling the property later on.

Finally, by recognising the issues presented by Japanese Knotweed and understanding that that the professional solution available is the one which best resolves this pervasive problem will really help stem the growth of this national nuisance.