What is Balsam and why is it a problem?

Himalayan balsam may look pretty with its pink flowers, but it causes real problems for local wildlife, rivers, and community green spaces. It spreads rapidly if not managed.

Why Is Himalayan Balsam a Problem in the UK?

Himalayan balsam may look pretty with its pink flowers, but it causes real problems for local wildlife, rivers, and community green spaces. It spreads rapidly if not managed.

Himalayan balsam is a tall plant originally brought to the UK in the 1800s as a garden ornamental. It quickly escaped into the wild and now grows in many habitats but mostly along riverbanks, canals, woodland edges, and damp areas.

A quick guide to why it’s a threat to our UK habitats

1. It Takes Over and Pushes Out Native Plants

Himalayan balsam grows rapidly and forms dense patches, crowding out the plants that local wildlife depends on. Scientific studies show it reduces native plant diversity and affects insects that rely on a mix of species.

2. It Causes Riverbank Erosion

This is one of the biggest problems:

  • In summer, it shades out other plants.
  • In winter, it dies back completely, leaving riverbanks bare. It’s shallow root structure means riverbanks are left exposed.
  • Bare banks are easily washed away during winter rain and high river flows.

UK research shows balsam invaded river banks erode much more quickly than healthy, vegetated ones.

Peer reviewed studies in the UK and Europe also found significantly higher erosion where balsam is present.

This erosion puts pressure on local communities by increasing flood risk, damaging wildlife habitats, and costing more to repair riverbanks.

3. It Spreads Extremely Quickly

Each plant can produces around 800 seeds (4-16 seeds per pod meaning 150-200 pods per plant). These pods explode, firing seeds up to 7 metres away.

Once it arrives in an area, it can take over within a single season! This is why we need to take action and manage the spread of this plant.

4. It Harms Wildlife

Because it pushes out other plants, many insects, including bees, butterflies, and dragonflies, lose food sources.

Aside from their food source (insects) some birds and mammals are also effected, such as the endangered water vole, which depend on thick, stable riverbank vegetation, which balsam destroys.

5. It Can Increase Flooding

As balsam dies back, the loose soil and dead plant matter can wash into rivers, contributing to blockages and increasing flood risk.

For more information about Himalayan Balsam and why it is such a big problem for UK wildlife, check out this blog by The Wildlife Trust for Lancashire, Manchester and North Merseyside.

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