Japanese knotweed can make people's homes impossible to sell. The plant is non-native and invasive, meaning that it completely takes over.
One home owner from Maesteg told ITV News that his home is worth much less than it should be due to the Japanese knotweed growing around his house.
Robin Waistell won £15,000 of compensation last year from Network Rail in a landmark case after the plant which grows on the railway line next to him home started becoming a nuisance on his property. However, the case is now being appealed.
Watch Hannah Thomas' report: