Seen this in your garden while you're safe at home? Here's what you need to do...

Experts give advice on how to deal with Japanese Knotweed after hotspots emerge in Northamptonshire
Picture shows: Japanese knotweed in its spring growth phase (Credit: Environet UK)Picture shows: Japanese knotweed in its spring growth phase (Credit: Environet UK)
Picture shows: Japanese knotweed in its spring growth phase (Credit: Environet UK)

Homeowners in Northamptonshire who are spending more time than usual in their gardens during the current lockdown may be concerned to discover red asparagus-like shoots quickly growing into lush looking shrubs with distinctive heart shaped green leaves and pink-flecked stems - possibly Japanese knotweed as it enters its spring growth phase.

Exposed: The Japanese Knotweed Heatmap, launched and managed by knotweed experts Environet UK to provide a comprehensive live record charting the spread of the UK’s most invasive plant across the country, has identified the following local hotspots:

Hide Ad
Hide Ad

The number of hotspots identified in Northamptonshire are: Wellingborough, 19, Northampton, 16, and Kettering, four.

Described by the Environment Agency as “indisputably the UK’s most aggressive, destructive and invasive plant”, Japanese knotweed grows rampantly along railways, waterways, in parks and gardens and is notoriously difficult to treat without professional help.

It can reduce a property’s value by around 10 percent and make it difficult to sell unless a treatment plan is in place with an insurance-backed guarantee, which will satisfy mortgage lenders. Homeowners who discover the plant can report it on Exposed using the ‘Add sighting’ feature, uploading a photo for verification by experts.

According to Environet UK, about four to five percent of the UK’s houses are currently affected, either directly or indirectly (e.g. neighbouring a property where it’s present) but despite the plant’s fearsome reputation, homeowners should not panic if they find themselves in lockdown with this unwelcome guest.

Environet offers the following advice:

Hide Ad
Hide Ad

* Identify any suspicious plants. Japanese knotweed starts growing rapidly in March and April, when red spears emerge from the ground, turning green before forming hollow canes. If you’re not sure what you’re looking for, email a photo to [email protected] for free identification. Plants commonly confused for Japanese knotweed include Bindweed, Russian Vine and Ivy.

* In most cases knotweed can be dug up during the lockdown period. As the work is undertaken outside and there’s no need for a treatment professional to enter a property, it’s still possible to excavate knotweed as long as social distancing measures can be safely observed. Contact a professional removal firm and arrange a remote survey using Facetime or by sending photographs.

* Don’t panic if this is not possible, for example at a terraced property with limited rear access. Homeowners can still make arrangements to have the invasive plant removed when restrictions are lifted and the work will typically only take a couple of days. While it’s always best to treat or remove Japanese knotweed as soon as possible, in most cases it won’t do too much harm to leave it happily growing for the next few weeks.

* Herbicide treatments don’t take place until early June anyway when the plant is in full leaf. Make arrangements now for peace of mind and to ensure you’re at the front of the queue.

Hide Ad
Hide Ad

* If you’re hoping to sell your home, use this time to deal with the problem and secure a 10-year insurance-backed guarantee for the work, to help your sale progress smoothly once lockdown is over. Sellers are legally obligated to inform buyers if a property is or has been affected by knotweed and could be sued if they fail to do so.

* Don’t be tempted to tackle Japanese knotweed yourself. Methods attempted by homeowners to kill the plant include mowing it, covering it to deny sunlight, setting fire to it, dousing it in bleach or petrol and even electrocuting it! But none of these measures are effective at killing the plant’s vast underground root system and you could inadvertently aid its spread. Plus, Japanese knotweed waste can’t be put in a green bin. It’s classed as controlled waste and needs to be disposed of at an authorised landfill site.

Nic Seal, Founder and MD of Environet, said, “Our message to homeowners who discover Japanese knotweed growing in their garden over the next few weeks is not to panic and resist the temptation to deal with it themselves.

“In most cases knotweed can still be removed during the lockdown period, but if this isn’t possible it won’t make a huge amount of difference to leave the plant growing until restrictions are lifted. A failed attempt to dig it up could help it spread and spraying the plant with herbicide makes professional treatment more difficult further down the line. Where we cannot treat or remove knotweed due to current Covid-19 restrictions, we pledge to tackle at no further cost any resulting spread on clients’ property.”

Hide Ad
Hide Ad

Exposed: The Japanese Knotweed Heatmap is a free online tool for anyone seeking information on the spread of knotweed in their local area. Users can visit https://environetuk.com/exposed-japanese-knotweed-heat-map and enter their postcode to discover the number of reported cases nearby, with hotspots highlighted in yellow or, in the most severe cases, red. Over 93,000 postcode searches have been undertaken since the launch of Exposed in spring 2019.