A residential area in Lancashire has emerged as the most affected postcode in Britain for Japanese knotweed infestations, according to recent data from invasive-plant specialist Environet UK. The BB3 2 postcode in Whitehall, Darwen, recorded 92 separate cases, contributing to Blackburn with Darwen borough’s status as the country’s worst-affected area, with 2,135 reported incidences—equating to roughly 40 per square mile.

Japanese knotweed, known for its rapid growth and robust root system, poses significant challenges to property owners as it can cause structural damage, reduce property values, and complicate real estate transactions.

Nathan Hannaway, 33, a recent buyer in the BB3 2 postcode, described the financial and personal impact of discovering a hidden infestation in his home’s garden shortly after moving in last year. Hannaway purchased a five-bedroom Victorian semi-detached house for £430,000 with his partner and two children. Following a neighbor’s inquiry, Hannaway noticed five knotweed shoots, which had apparently been cut back, growing on the property. A survey conducted by Environet UK later confirmed the presence of the plant in three separate garden areas.

Hannaway said he was quoted £15,000 for knotweed removal and is currently involved in a civil dispute with the previous owner, alleging non-disclosure of the infestation during the sale process. “It was infuriating,” he said, expressing frustration over the situation.

Local residents emphasize the invasive plant’s resilience and ability to spread quickly if not properly managed. Brian Hartley, 84, a neighbor in the area, warned that Japanese knotweed “spreads like wildfire” if left unchecked. Similar concerns were noted at Blackburn Old Cemetery, where fresh knotweed growth has been cordoned off to prevent lawnmower activity from dispersing root fragments and accelerating the spread.

Maurice Ffelan, 82, a local observer, highlighted the difficulties of eradication efforts: “It’s a bugger to get rid of. It can grow to 10ft tall.” The plant is capable of growing up to four inches per day during summer, reaching heights close to 10 feet within a single season. Volunteers combat the infestation by injecting glyphosate weedkiller directly into mature stems in attempts to destroy the underground root network. Ffelan cautioned that improper mowing can inadvertently aid the plant’s proliferation by spreading fragments, leading to new growth in previously unaffected areas.

The prevalence of Japanese knotweed in Lancashire underscores ongoing challenges for homeowners and local authorities dealing with this invasive species. Effective control requires vigilant management to prevent further environmental and economic damage.