A major Stoke-on-Trent firm hit by a severe Japanese knotweed outbreak has been forced to bury hundreds of tonnes of infested soil deep beneath its property.

RJS client and Japanese Knotweed Expert boss Jason Harker says the damaging shrub is thriving in the city’s unused brownfield sites, canals, and railway embankments – and around people’s homes.

An Environet spokesperson said: “The aggressive nature of the plants and ability to survive in unfavourable conditions means that they can cause damage to the built environment. We often see cases of damage to hard surfaces such as patios, asphalt, and drains.

This hardy plant, tough enough to thrive in Japan’s mountainous and volcanic terrain, was originally brought to the UK in the Victorian era as a specimen plant. Its heart-shaped leaves and pollen-rich white buds make an attractive addition to thousands of gardens and grow between spring and autumn. However, it has since become known that it is dangerous to native plant life and property, as it can force its way through minor cracks in concrete.

Anyone who puts it in their green or brown bin can be fined £5,000 – and for businesses, the penalties can stretch to £20,000 and a six-month jail sentence for directors.

It has only been reported to have caused severe damage to a minority of houses. More often, you see it causing minor damage through tarmacked areas outside people’s homes, like their driveways.

However, it’s the effect it can have on the value that’s a problem, and it can complicate buying and selling a property. The potential consequences can arise from the TA6 form, which asks whether there is Japanese knotweed on your property, giving you the option to answer ‘yes’, ‘no’ or ‘don’t know’.

If you select ‘no’, you need to be certain none is growing on your property – or within three metres of the boundary. By putting ‘no’, you’re accepting all the liability and the average legal claim if it turns out you’re wrong is £34,000 for misrepresentation.

It is not illegal to have it growing in your garden, and you don’t have to declare it to the council or Environment Agency. But if you let it cross the boundary into your neighbour’s garden – even if it’s at the root level and not visible – that becomes a serious issue.”

It is recommended that people maybe considering having a specialist survey conducted at a cost of around £300, as the risk of liability and the cost of dealing with it down the line should be alleviated.

We believe, the shrub is growing throughout Stoke-on-Trent. But its highest concentration is in the city’s north, from Hanley up to Kidsgrove. It is less prevalent in rural parts of North Staffordshire, with the worst hotspots in the country said to be Liverpool, Manchester, and central London, where there are more mothballed brownfield sites.