Colonising rail and river banks, wastelands and woodlands, Himalayan balsam was introduced to the British Isles in 1839 by Victorian plant hunters who were keen on its beautiful pink flowers and exploding seed pods. The plant has had plenty of time to establish in the UK and, over the last 50 years, has spread rapidly.
But Himalayan balsam is a problematic plant. It competes with native plants for light, nutrients, pollinators and space, excluding other plants and reducing biodiversity. It dies back in the winter, leaving river banks bare and open to erosion. Dead leaves and plant debris from the weed block waterways and lead to flooding.