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Gardeners recruited to help spot next Japanese knotweed before it 'jumps the garden fence'

Helena Horton
Japanese Knotweed was once an ornamental plant, but now it destroys homes - Alamy

Gardeners are being recruited to find the next Japanese Knotweed before it 'jumps the garden fence' in a new project spearheaded by the Botanical Society of Britain and Ireland (BSBI).

Japanese Knotweed and Himalayan Balsam both originated as ornamental garden plants, before they spread across the UK and caused havoc to homes and waterways.

Now, green-fingered British people have been asked by BSBI and the University of Coventry to help identify whether any new garden plants could end up becoming a menace to the countryside.

The new citizen science project called Plant Alert offers gardeners on the frontline a quick and easy way of reporting any ornamental plants showing signs of invasiveness.

Gardeners are the best people to be able to keep an eye out for potentially hazardous plants, as these are the ones which have to be carefully managed in the garden to make sure they are not overgrowing other plants or spreading into other flowerbeds or onto the lawn.

Scientists say the traits that should be watched out for are vigorous growth, prolific self-seeding, longer flowering periods and any plant which the gardener has to ‘keep on top of’ to prevent it spreading.

Plants which are logged on the Plant Alert app will be studied by botanists and potentially restricted from sale.

Kevin Walker, Head of Science at the Botanical Society of Britain and Ireland, explained: “Bitter experience has shown that species that are invasive in gardens are also the ones that are likely to 'jump the garden fence' and cause problems in the wild; usually because they can regenerate very effectively and grow vigorously, outcompeting native species.

"The most effective way to reduce the impacts of these species is to identify them before they escape into wild - this is exactly what this project aims to achieve. Armed with this information we can then alert others to the threats they pose allowing policies to be put in place to prevent their sale and implement eradication programmes in case they do manage to escape”.

With British people spending more time in their gardens this year, they should be better placed to spot any plants causing potential problems.

Dr Katharina Dehnen-Schmutz , Plant Alert Co-ordinator, added: “Ornamental plants escaping from gardens are the main pathway for non-native plants outnumbering native plant species in the British flora, with some of them having high negative impacts on ecosystems, biodiversity and the built environment. While non-native plants play a vital role in gardens, the challenge now is to identify the small number of possible future invasive plants with potentially high negative impacts, out of the ever-increasing pool of about 70,000 ornamental plants available to gardeners”.