Are other European countries more innovative and proportionate in their approach to Japanese Knotweed than the U.K.? How do various European jurisdictions deal with this difficult plant? Despite the fact that other plants cause a similar level of physical damage to property as Japanese knotweed, the stigma attached to knotweed in the U.K. means that the reaction to its presence (as evidenced by property valuations) may be disproportionate.

Our colleagues in Germany, for example, report that knotweed is simply not a hot topic. The approach there is a pragmatic and sensible one – due to costs, landlords rather than tenants are responsible for its removal. There is also a “self-help” remedy available if a neighbour allows knotweed to encroach on your land, allowing you to remove it and get compensation.

Similarly in Hungary knotweed does not seem to have a major influence on buying or lending decisions. Anyone who allows knotweed to grow and spread may be fined and required to eradicate it. If that person can’t be found, the owner, tenant or manager of the property has to deal with it. But our colleagues tell us it is not a thorny issue in the same way as in the U.K..

In France the approach is even more “hands off”. There are certain non-native species of plants which cannot be introduced into the environment. However, Japanese knotweed doesn’t appear on that list. It is not considered as an invasive alien species and can be planted in France. There are certain rules such as farmers must not plant it near watercourses, but the French policy framework is less zealous than in the U.K..

So is the U.K. approach “overly cautious” compared to our European neighbours? Some of the standards set out in the Royal Institution of Chartered Surveyors’ risk assessment have been criticised as arbitrary. The “seven meter rule” (i.e. if knotweed is visible within a seven meter radius of any building or the property boundary, then the property is deemed higher risk) is not based on scientific evidence. Therefore, many commentators have demanded a more nuanced approach to risk classification which would factor in the size of the infestation, the distance from the property and the property type. The U.K. government has agreed that more evidence is needed, particularly on the way in which knotweed is treated in other jurisdictions. Stay tuned to find out more as these knotty issues are unravelled!