Landowners will be able to claim damages if the "pernicious" Japanese knotweed has encroached on their property following a Court of Appeal ruling.
In a decision which could have wider implications for landowners across England and Wales, three leading judges ruled in favour of two householders whose properties had been affected by the hazardous plant.
The bamboo-like plant, which grows quickly and strongly and spreads through its underground roots or "rhizomes", can undermine the structural integrity of buildings and is expensive to treat.
Stephen Williams and Robin Waistell, who own two adjoining bungalows in Llwydarth Road, Maesteg, South Wales, made a claim against Network Rail - which owns the land immediately behind their properties.
Japanese knotweed has been present on Network Rail's land at that location for at least 50 years and the pair first complained about encroachment on to their land in 2013.
They later brought a successful claim against Network Rail at Cardiff County Court and were awarded damages in February last year.
Network Rail challenged that decision at a Court of Appeal hearing last month, but the court ruled that the homeowners were entitled to damages because the plant's rhizomes had extended beneath both of their properties.
Announcing the decision in London on Tuesday, Master of the Rolls Sir Terence Etherton said: "Japanese knotweed, and its roots and rhizomes, does not merely carry the risk of future physical damage to buildings, structures and installations on the land.
"Its presence imposes an immediate burden on landowners who face an increased difficulty in their ability to develop, and in the cost of developing, their land, should they wish to do so, because of the difficulties and expense of eradicating Japanese knotweed from affected land.
"In this way, Japanese knotweed can fairly be described as a natural hazard which affects landowners' ability fully to use and enjoy their property and, in doing so, interferes with the land's amenity value."
However, the judge - sitting with Lady Justice Sharp and Lord Justice Leggatt - said the homeowners would not be entitled to damages because the knotweed had reduced the value of their properties.
The court refused to give Network Rail permission to challenge the ruling in the Supreme Court.