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Japanese knotweed · Dublin

Japanese knotweed in Dublin: 364 public records

Public biodiversity records hold 364 Japanese knotweed sightings for Dublin, the latest from 2026. A record near the house is a mortgage question, not a gardening one.

Figures compiled from the public records listed at the foot of this page. Data snapshot: . Updated when the records change.

Check one house in Dublin

364 Japanese knotweed records in Dublin, latest 2026.

One specific house in Dublin: knotweed records within 250 m of that Eircode, flood zone, radon, planning applications within 300 m, BER, sale history. Thirty-eight checks in all, each linked to the public record.

€19.99, free snapshot first. No account.

Or read the sample report first: a real house, 16 pages.

364

Japanese knotweed records in Dublin (GBIF / NBDC)

305

giant hogweed records

2026

most recent record year

Knotweed in Dublin

Japanese knotweed spreads along rivers and railways and from dumped garden waste. It goes three metres down and seven metres out, comes up through tarmac and drains, and a piece the size of a fingernail regrows. In Dublin, public biodiversity records (via GBIF, mainly the National Biodiversity Data Centre) hold 364 knotweed sightings. Counts depend on who was recording: a county with an active recorder scores high.

Records within 2 km of town centres, for the towns we hold detail on:

Rathmines109 records
Ranelagh103 records
Donnybrook95 records
Rathgar88 records
Cabra74 records
Ballsbridge70 records
Dublin 769 records
Churchtown68 records
Sandymount64 records
Harolds Cross64 records
Drimnagh55 records
Glasnevin54 records

For a house, what matters is a record within about 250 m, and the lane or stream behind the garden. Walk the boundary at a viewing; the stems are hollow, bamboo-like, with red speckles, and the leaves are shield-shaped.

Other checks for Dublin

Designated parts of the Fingal County Council area are in the Defective Concrete Blocks grant scheme (mica and pyrite in blocks). Only those parts are covered, not the whole county, so ask the council whether a particular address is inside the designated area.

Dublin is in the pyrite belt. Houses built roughly 1997 to 2013 with hardcore from the affected quarries may have heave in floors; the Pyrite Resolution Board ran the remediation scheme. The report flags the build years and the scheme for the exact house.

Other checks for Dublin

Other counties

GuideJapanese knotweed in Ireland: how to spot it, what lenders do, what it costs

Questions people ask

How common is Japanese knotweed in Dublin?
The National Biodiversity Data Centre and other recorders have logged 364 knotweed records in Dublin (669 including giant hogweed), the latest in 2026. Records cluster along rivers, railway lines and roadsides, and reflect where people record as much as where the plant grows.
Will a bank lend on a house with knotweed?
Irish lenders have no blanket rule, but valuers now note it, and where it is within seven metres of the house they may ask for a management plan or knock the valuation. UK lenders decline outright. Ask the seller in writing whether it is or was on the property and for treatment records.
What does it cost to deal with?
Herbicide treatment runs three to five seasons at a few hundred euro a year for a small stand. Excavation and licensed disposal for a large stand runs into five figures. Never cut it and put it in the green bin: a fragment regrows.

Sources

Area figures, compiled from public records. They describe the town or county, not any one house. The paid report checks the exact Eircode.