Himalayan balsam

Meet the plant

Himalayan balsam (Impatiens glandulifera) is an attractive plant, with a stout, hollow stem, trumpet shaped purple-pink flowers and elliptical shaped green leaves. It grows in dense stands and can be up to 2m tall. It has an explosive seed capsule, which scatters seeds over a distance of up to 7m.

It grows mostly on river banks and in damp woodlands.

It was brought to Kew Gardens in 1839 from Kashmir, and has spread into the wild from there via seed dispersal – by people passing seed to others for garden planting and by seeds spreading from plants and establishing outside garden planting, for example by floating down rivers and becoming lodged and germinating in soft muddy banks.

Download the Himalayan balsam ID guide

Impacts

Himalayan balsam grows in dense stands and it shades and crowds out many native species. It produces much nectar and is, therefore, attractive to pollinating insects, to the detriment of native flowering plants (which are less visited by these insects and are, therefore, less effectively pollinated).

Once established, it dominates riverbanks in summer but, in winter, when the plant dies back, it leaves bare and exposed banks which are vulnerable to erosion as the shallow Himalayan balsam root system offers limited stablisation. Dense stands can also impede the water flow at times of high rainfall, increasing the likelihood of flooding.

Learn more

Report a Plant Sighting

If you've seen one of our key invasive plant species - tell us about it.

Report a Plant Sighting

Himalayan balsam management

Himalayan balsam is widespread across our project area and is a common sight on many river banks in Scotland the British Isles. It is an annual plant, meaning that it grows, flowers, seeds and dies all within one season – therefore, the aim of control is to remove the plant each year before seeding occurs. To do this, control takes place in the early summer months before seeds ripen and seed pods ‘explode’ scattering seeds later in the summer.

Seeds can remain viable in the soil for two years, so populations of balsam can be removed after 2 or 3 years of consistent control. However, for eradication to be successful, control needs to be strategic to ensure that all plants upstream have been removed, as seeds from these sources can be transported down river and quickly re-infest areas, and effective at each site to remove all plants before seeding takes place.

Our strategy for controlling Himalayan balsam is to work with local volunteers, community groups and land managers, engaging them in control and encouraging local ownership of their sites so that plants are removed and pulled year after year.

Himalayan balsam control

Hand pulling

The shallow root system means that Himalayan balsam is very easy to pull from the soil by hand. Plants can then be piled into a heap where they compost down, or for individual plants, stems can be hooked over a branch to dry. If plants are left on the ground there is a risk they will re-root.

The best time for pulling Himalayan balsam is in the early to mid summer, from May to around July/August – before the seed pods ripen. After this time control should be stopped as disturbance of the seed pods will cause them to explode, spread seed and make the problem worse.

We work with lots of volunteers and community groups to pull Himalayan balsam as its control activity is easy to get involved with – and it’s certainly a case of many hands make light work!
Cutting or Strimming

An alternative option for controlling Himalayan balsam is to cut the plant with a strimmer or a hand tool e.g. a weed slasher or a scythe. The important thing when cutting is to make sure that the stem is cut below the first node i.e. close to the ground. If cut above this node the plant will re-grow and potentially set seed.

It is critical that cutting is only carried out before the seeds form and so this is an early summer activity.

We have used this technique where we have large, monoculture stands of Himalayan balsam – in these circumstances it is quicker and more efficient than hand pulling.

Read more about Himalayan balsam control in our blog