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Himalayan balsam pink trumpet shaped flowers


Himalayan Balsam was introduced to Britain in the 19th century as a herbaceous, annual plant. It grows from seed to up to 2.5m in height in a single growing season, flowering in summer and setting seed in the autumn. The plant has hollow, shallow rooted stems with leaves growing opposite each other, and has white, pink or purple flowers up to 4cm long.


Himalayan Balsam is commonly found growing in damp, shaded areas, such as the banks of slow-moving watercourses, rivers, streams and waste ground. Its vigorous growth and dense stands block out sunlight, outcompeting native plants and causing biodiversity issues. When the stands die back in winter, it leaves bare banks and can increase the risk of soil erosion. The sweet scented flowers can also attract pollinators away from native species.


Early intervention is important to limit Himalayan Balsam's impact on biodiversity and prevent it spreading. It is an offence under the Wildlife and Countryside Act 1981 to cause it to grow in the wild or plant it in the wild.


Features of Himalayan Balsam

Image of Himalayan Balsam features - flowers and leaves
  1. Seed pods grow up to 3cm long and contain 16 seeds, 2-3mm in length. A single plant can produce 800 seeds, which explode from the pod and can travel up to 7m from the plant. Seeds are buoyant allowing them to spread along watercourses. The seed bank can remain active for up to 2 years.

  2. Trumpet-shaped, sweetly scented white, pink or purple flowers which appear in summer. They are 2.5 to 3cm in length.

  3. Finely serrated-edged whorls of 3-5 leaves form at the joints on the stem. These are green with a pink mid-rib, growing up to 25cm long and 7cm wide.

  4. The fleshy, brittle, hollow stems reach up to 5cm in diameter. They are green to red in early growth and turn pink to red later. The plants can grow 2.5m in height.

Types of Himalayan Balsam Treatment

  • In-situ herbicide treatment: This is the application of herbicide to the foliage. It immediately kills the plants and is effective for treating large stands. It is less labour intensive and intrusive.


  • In-situ manual treatment: Hand pulling or cutting down the plant immediately kills the adult plant and can be effective for controlling small, isolated stands. It is also ideal for sensitive areas not suitable for herbicide treatment.


  • On-site treatment, ex-situ: Himalayan Balsam contaminated soil is excavated and moved to a more convenient area of the side for stockpiling and ongoing herbicide treatment.


  • On-site burial: Contaminated soil is buried at least 2m deep within a convenient area of the site.


  • Off-site disposal: This option can be used as a last resort when other options are not viable.

Himalayan balsam stand with dense growth

ERS has extensive experience in identification, management and remediation of Himalayan Balsam infested sites. We work with clients to develop a treatment strategy which meets the client's timescales, budget and future development requirements.


When Himalayan Balsam is identified on a site, ERS can develop and implement a Himalayan Balsam Management Plan. The plan is essential for both the current owner and any future owners as a record for treatment of the site.


To enquire about a survey or management plan for Himalayan balsam on your site, contact us today to speak to one of our Invasive Weeds experts.

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