All About Himalayan Balsam


Jodie Rochford (Volunteer)

Jodie explains the damage caused by this alien invader, and what we can do to stop it spreading.

This blog has been written by Jodie Rochford, a volunteer for Severn Rivers Trust.

What is Himalayan Balsam and why is it such a problem?

Himalayan Balsam is a plant that was introduced into the UK from the Himalayas in 1839 as a garden plant but soon spread across the UK, especially around our waterways [1]. It is an invasive species that is causing many problems within our ecosystems.

Himalayan Balsam is a fast growing plant that produces up to 800 seeds which get dispersed about 7 m from the 'explosive' seed pods [3]. This effective dispersal method results in dense areas of the plant which grow up to 2.5m high [2] and block out sunlight and space. this in turn prevents other species from growing and greatly reduces plant biodiversity [1].

Reducing the number and variety of plants in a local area means a loss in available habitats and food sources for invertebrates. In places where balsam has taken hold, we see around a 75% decrease in spider species, and a 64% decrease in beetle species [5]. Invertebrate species are vital for pollination of wild pants and crops, for maintaining healthy soil structure and fertility. Bugs are also a food source for other animals and are crucial in the cycle of nutrients [4].

Balsam is also a prolific producer of nectar, attracting bees, so they tend to neglect other local plants. This reduces plant fertilisation and production of seeds, subsequently diminishing the numbers and varieties of different plants locally [5].

Balsam causes riverbank erosion when the plant dies off in winter and leaves the riverbank exposed to subsidence and erosive forces during high water levels. Exposed riverbanks increase the risk of flooding, as riverbank vegetation has a significant role in slowing runoff and flood waters [5].

Himalayan balsam in flower. Image used under license form

It is vital that we reduce the spread of Himalayan Balsam to preserve natural riverbank biodiversity and reduce erosion, soil loss and flooding.  

How to identify Himalayan Balsam

Himalayan Balsam germination occurs in February and March, with rapid growth in stems and leaves in April [5]. It is seen from spring to autumn and produces flowers between June and October. It is mainly found along waterways, and in ditches as it can thrive in areas of low light levels [3].

The main identification characteristics of Himalayan Balsam are the stems, flowers, and leaves. The stems are hollow, green-reddish, and can be 2-3m high. The flowers can be white, pink, or purple and have 5 petals in a helmet/hooded shape. The leaves are serrated and are a matt darkish green colour [5].

How can you help to reduce the spread?

Himalayan Balsam needs to be pulled out in early summer (March to early July) before seed dispersal, as seeds can last up to 3 years [5]. It can be easily removed by pulling the plant out or cutting the stem under the first node. It is not toxic and there are no thorns, so it is safe to be pulled out of the ground by hand [5]. Pulling out the plant will stop the plant from producing the seed pods which will help prevent it from spreading further. Once the plant has been pulled out, it can be left on the ground to naturally biodegrade [5]. It is important to keep safe if you are pulling balsam, do not attempt to reach plants on steep sided banks or close to the water’s edge.

Seeds can travel down waterways and travel by attaching themselves to vehicles, clothing, or footwear [5]. Therfore it is important to check your clothes and footwear before travelling to a different area – Check, Clean, Dry.

Get involved with Unlocking the Severn!

Unlocking the Severn, one of our ongoing projects, works closely with Bewdley Civic Society, in Bewdley near Worcester. The Civic Society have been helping to control the spread of Himalayan Balsam in this area for the past 6 years! The group meet each summer to do ‘Balsam Bashes’ in July and we’d love additional volunteers to come along and help us control this harmful plant species. If you are interested, please contact for more information. Alternatively, you can keep an eye out for our information posters in the Bewdley area with details of how to get involved.


1.      The WildlifeTrusts. 2021. Himalayan balsam | The Wildlife Trusts. [online]Available at: <>[Accessed 25 April 2021].

2.      National Trust.2021. Himalayan Balsam – it’s an alien plant invasion. [online]Available at: <>[Accessed 25 April 2021].

3.      RoyalHorticultural Society. 2021. Himalayan balsam. [online] Availableat: <> [Accessed 25 April2021].

4.       Scudder, G., 2017. Insect Biodiversity:Science and Society. 2nd ed. John Wiley & Sons, Inc.

5.      Inside Ecology.2021. Invasive non-native species (UK) – Himalayan balsam – InsideEcology. [online] Available at: <>[Accessed 25 April 2021].

6.      Fish Pass.2021. Fish Pass - Contact. [online] Available at:<> [Accessed 5 May 2021].

7. Himalayan balsam. [online] Available at:<>[Accessed 8 May 2021].

8.      Environet UK. 2020. IdentifyHimalayan Balsam| Environet. [online] Available at: <>[Accessed 8 May 2021].