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So many knots, such little time

03 Jun 2016   |   0 Comments

Japanese Knotweed is not just a threat to residential properties and their house prices. It can also badly affect the development and maintenance of commercial property and affect the ability to get a secured loan or insurance. It is estimated that Japanese Knotweed costs the UK economy £166 million per year in home devaluations and treatment. A reputable trade association should provide you with details of local contractors who can tackle Knotweed. Professionals can charge between £1,500 and £3,000 to remove a severe problem. The treatment should involve repeat visits for at least five years and should come with an insurance backed guarantee that it will not be returning.

Japanese Knotweed was brought to Europe by a doctor called Phillipe von Siebold who found it growing on the side of volcanoes in Japan. He began to sell it to botanical gardens and high society figures in Britain. It was initially lauded for its beauty, and potential as animal feed. In 1847, it was named the “most interesting new ornamental plant of the year,” by the Society of Agriculture and Horticulture at Utrecht in Holland.

Japanese Knotweed's spread – through purposeful planting and it escaping – went undetected for years. Once it escaped the confines of “beauty” and “animal feed,” it began its destructive tirade across the UK. According to researchers at the University of Leicestershire, people sharing cuttings or disposing of unwanted plants was the "primary pattern of distribution.” Teamed with the movement of soil for construction and roadbuilding, it wasn’t long before Japanese Knotweed was spreading rapidly.

One of the earliest examples of it being planted purposefully outside gardens, was in Welsh coal-mining valleys in the 1960s and 70s, as it was good for stabilising loose soil. In the Japanese volcanic landscape, the spread of Knotweed never arose due to the regular deposits of ash. This enabled the plant to remain small whilst surviving due to energy stores in its deep root system.

The difficulties with Japanese Knotweed near property are caused by its relentless growth and a talent for emerging though concrete and tarmac. Furthermore its roots can embed into the ground up to seven metres deep. At its most prolific, it can grow up to 20cm per day. Within a couple of weeks, what starts as a seemingly harmless plant, can be become a monstrous ambush of leaves. By ten weeks, its potential of becoming the size of two fully grown adults is undeniable, at an estimate of three to four metres. Underground, its roots having spread up to seven metres, can compromise the structure of buildings.