The basis system can lengthen as much as three metres downwards and stretch as much as seven metres sideways, pushing via gaps in concrete, tarmac drives, walkways, drainage programs and cavity partitions
The “prime ten” places in Wales affected by Japanese knotweed have been recognized. Because the rising season for Japanese knotweed is in full swing, this invasive species may cause injury to properties, patios, paving and reduce the worth of land. Invasive plant skilled
Environet has now disclosed the Welsh areas most affected by knotweed in 2025, utilizing the newest figures from its on-line heatmap device, Uncovered: The Japanese Knotweed Heatmap. In whole, there are 31,338 confirmed sightings of knotweed throughout Wales, equating to three.9 cases per sq. mile, which is considerably increased than England’s charge of 1.1 cases per sq. mile.
Now that includes greater than 100,000 recorded cases of the UK’s most pervasive plant, the map is up to date with new confirmed sightings all year long, providing probably the most thorough on-line report of Japanese knotweed within the nation.
The general public can enter their postcode to search out out the variety of sightings of their neighborhood, with high-risk areas marked in yellow, orange or, in extreme circumstances, crimson.
This helps them gauge the potential threat to their property or one they’re contemplating buying.
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They will additionally contribute to the heatmap by reporting knotweed infestations utilizing the ‘Add Sighting’ operate and attaching a photograph of the plant for skilled verification.
The info exhibits the worst locations in Wales are Newport metropolis, Cardiff metropolis and Swansea metropolis.
Wales’ High 10 Japanese knotweed hotspots for 2025 are:
Incidences
1. Newport metropolis – 1,239
2. Cardiff metropolis – 949
3. Swansea metropolis – 936
4. Llanelli, Carmarthenshire – 693
5. Betws-y-Coed, Conwy – 421
6. Neath, Neath Port Talbot – 396
7. Dolwyddelan, Conwy – 298
8. Llanafan, Ceredigion – 289
9. Rogerstone, Newport – 268
10. Tanygrisiau, Gwynedd – 254
Japanese knotweed made its debut in Britain in the course of the Victorian period, arriving in a set of plant specimens despatched to Kew Gardens and was swiftly embraced by gardeners and horticulturalists who remained oblivious to its harmful potential.
The plant begins sprouting in early spring, quickly growing into dense inexperienced bushes that includes pink-speckled stems, heart-shaped foliage and bamboo-style canes.
Nevertheless, it will probably create important complications for property house owners.
Its subterranean root system can lengthen as much as three metres downwards and stretch as much as seven metres sideways, pushing via gaps in concrete, tarmac drives, walkways, drainage programs and cavity partitions.
While extreme property injury stays unusual, mortgage suppliers demand knotweed therapy earlier than property gross sales, probably triggering neighbourhood disputes and decreasing property values by roughly 5 per cent, in accordance with Environet.
A 2023 DEFRA research estimated the expense of addressing knotweed prices the UK financial system virtually £250 million yearly. Environet Director Emily Grant commented: “By mapping verified sightings, we’re serving to folks perceive the extent of threat of their native space and inspiring early identification and therapy.
“Vigilance is the easiest way to guard your property from Japanese knotweed, ensuring you deal with it as early as potential earlier than it turns into properly established. Presently of 12 months, knotweed is in full progress mode and straightforward to identify with its vivid inexperienced heart-shaped leaves which develop in a zigzag sample up the stems.
“Mature crops flower round August, after they produce clusters of tiny white blooms.”
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