Himalayan Balsam

Himalayan Balsam (Imaptiens gladulifera)

Himalayan Balsam was first introduced to the UK in 1839. It is now one of the most invasive and damaging plants in the UK.
It is an attractive, non-native annual plant., related to the busy lizzie. It usually grows to between 1 and 2 meters tall, making it the tallest annual in the UK. The plant is particularly frequent along the banks of watercourses and damp woodland. Each plant produces about 2,500 seeds , which are catapulted a considerable distance from the parent plant. A seed density of over 5000 per square meter. can occur in established sites .Local residents are concerned that this catapulted distribution method could result in severe eye injury to children playing in the dense growth.
The dense swathes of the plant block out light to the ground, killing native plants including grasses. When the plant dies back in October the ground is left bare and soil erosion becomes a major problem. The seeds float , and indeed can germinate in water on their way to new sites making watercourses a prime dispersal route.. It has already destroyed many chalk streams in the south of the UK.
There is currently a debate on whether the plant should be added to the 1981 Countryside Act, as the other major invaders such as Japanese Knotweed.

Control is relatively easy, however once a colony is established it becomes very labour intensive.
Before flowering in June, the plant can simply be uprooted (but beware it continues growing in damp areas, even when uprooted), else cut below the first node. If nodes are left, the plant simply sends out more branches. Once the plant has set seed, it is too late as control methods help dissipate the seeds.

The good news is that the seeds are relatively fragile, and can survive only a few years. Thus control can be achieved in a relatively short period. Members of Blackrod and Horwich Environmental Action group are urging a concerted community effort over the next few years. Residents and particularly land owners are being asked to identify colonies of the plant this summer and put in place an action plant to control the plant next spring.

The order to change schedule9, of the Wildlife and Countryside Act, was made on the 9 March 2010


Himalayan Balsam Best Practice Management

RHS Himalayan Balsam