Britain’s Japanese knotweed hot spots revealed – here’s how to find out if the invasive plant is growing near you

UK’S hot spots for Japanese knotweed have been uncovered in a handy map showing where the invasive plant is growing most.

Introduced from Japan in 1825 as an ornamental plant, knotweed can erode the foundations of houses.

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The weeds can root deep in the ground, spoil gardens and also erode walls and foundations, which could make selling your home impossible.

Many mortgage lenders will refuse to lend money for a home near knotweed, and most insurers will refuse to pay for any damage caused.

Now invasive plant specialists Environet UK have released a heatmap you can use to see if your property is in a high risk area.

Hotspots are marked yellow to red depending on the severity of the infestation.

It shows London, Merseyside and Lancashire, Bristol, most of Wales and Glasgow as danger zones.

It allows users to search by zip code to determine the number of nearby reported sightings or to report new sightings.

In Tottenham, North London, for example, there are 232 reported infections within a 4km radius.

The plant can grow four inches a day in the summer, and its roots, or rhizomes, spread well underground, causing structural damage to buildings.

If it is found growing within 23 feet of a property it poses a risk, so mortgages are often denied unless there is a plan to eradicate it.

But even if the seller does the expensive work, the stigma attached to the investment means the property’s value can be as much as a tenth lower, even after steps are taken to control it.

The plant has distinctive red or purple shoots that resemble asparagus.

Its leaves are smooth, green, and scoop-shaped, with stems that look like bamboo canes with purple speckles.

Towards the end of summer it develops cream colored flower clusters.

As winter approaches, its leaves turn yellow and wither.