Spotted! The first Japanese knotweed shoots of 2022

The first Japanese shoots of 2022 have emerged on the banks of the River Plym in Plymouth, Devon, this week – more than a fortnight earlier than last year. The sighting marks the start of the growing season for one of the nation’s most notorious plants. 

Japanese knotweed conventionally hibernates during the winter months before emerging when the ground temperature reaches around 4°C/ 39.2°F. Previously, this would occur around late March, but it is getting earlier year-on-year. 

For the second consecutive year, the infamous weed has emerged in the south-west  of England (one of the warmest places in the UK). 

‘A few years ago, it was unheard of for Japanese knotweed shoots to emerge in February or March, but unfortunately, this now seems to be the norm,’ says Emily Grant, Environet’s Regional Director for the South West. ‘The warmer climate we enjoy in the south-west  of England certainly helps it along, with the UK’s first shoots spotted in Plymouth for the second year in a row.’

A recent study (opens in new tab) by the University of Cambridge similarly discovered that global warming is causing plants in the UK to flower on average one whole month earlier than previously. This is the case with this sighting. 

But what does this shoot mean for your garden? No matter how far away you live from the banks of the River Plym, it is important to know how to get rid of weeds and stop them from spreading – and Japanese Knotweed should be at the top of your hitlist. 

‘Homeowners across Devon and Cornwall should be vigilant for the distinctive red or purple spear-like shoots emerging in their gardens or near their homes over the next few weeks, as the knotweed growing season becomes established,’ Emily says. 

The garden expert explains that you should seek professional advice if you spot Japanese knotweed on your land. 

‘Implementing a professional treatment plan is the best way to prevent knotweed from causing damage to property, preserve the value of your home, and protect yourself from the threat of litigation from neighbors if it’s allowed to spread,’ she adds. 

This weed is a threat to small and large garden ideas, but you can now monitor its growth online. Exposed (opens in new tab), a live heatmap tracker allows you to discover the number of reported knotweed sightings around your property and the UK. 

The team encourages you to report any infestations by adding a photograph of the plant so it can be verified by experts. We’re bookmarking this tracker as we speak.