Invasive plant may have won the battle in Oslo

Amund Kveim, leader of the local group Østensjøvannets Venner, has spent 15 years fighting the invasive giant hogweed in Oslo, Dagbladet reports.

The plant, native to the Caucasus and introduced to Norway via grain imports in the 19th century, spreads rapidly and displaces local species. First observed near Kongsberg around 1802, it is now classified as highly invasive by Norway’s Species Information Centre.

Kveim and volunteers work weekly to remove the plant, which can regrow multiple times in a season. He advises cutting it down at least twice, ideally uprooting it entirely to prevent regrowth. Improper disposal, such as composting or dumping in wooded areas, risks further spread.

Each plant can produce up to 10,000 seeds annually, and the species also spreads via vehicles and soil movement during construction. While bees are drawn to its flowers, Kveim warns that the plant’s dominance threatens native biodiversity.

Østensjøvannets Venner, active since 1983, collaborates with municipal authorities to protect local ecosystems, supplementing official efforts with fieldwork and public education.