Meet the plant
Himalayan balsam (Impatiens glanulifera) is an attractive looking flower, with a stout, hollow stem, trumpet shaped pink/white 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 introduced into Kew Gardens, and has spread via its seeds – both individuals passing on the seed to others for garden planting and seeds floating down rivers before becoming lodged in soft muddy banks and germinating.
Download the Himalayan balsam ID guide
Read more about Himalayan balsam
Himalayan balsam grows in dense stands and it shades out and crowds out many native species. It produces much nectar and therefore is attractive to pollinating insects, to the detriment of native flowering plants (which are no longer visited by these insects and thus don’t get pollinated).
It dominates riverbanks and in the winter when it dies back its shallow root system is no help in stabilising the bare bank, which is then at risk of erosion. Dense stands can also impede the water flow at times of high rainfall, increasing the likelihood of flooding.
Management of Himalayan balsam
Himalayan balsam is widespread throughout our project area and is a common sight on many river banks. Balsam is an annual plant, so it grows, flowers, seeds and dies all within one season. The aim of control work is to remove the plant before seeding occurs - so in the early summer months, critically before the seeds ripen and seed pods 'explode' scattering seeds.
The seeds only persist in the soil for around 18 months, 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 first, otherwise seeds from these will float down river and quickly re-infect areas.
Our strategy for controlling balsam is to work with local volunteers, community groups and land managers, engaging them in Himalayan balsam control and encouraging them to 'take ownership' of their local patch of balsam and continue to pull it year after year. Sounds good in theory - but does it work? Find out how we've gone about engaging communities in the River Bervie Case Study.
Himalayan balsam pulling is something that everyone can get involved in, and together with volunteers and communities we've done an amazing 450 days of Himalayan balsam control over the last three years.
Himalayan balsam control
The shallow root system means that Himalayan balsam is very easy to pull out of the soil by hand. Plants can be piled into a heap and will compost down, or for individual stems can be hooked over a branch. If plants are left on the ground there is a risk they will re-root.
The best time for pulling Himalayan balsam is the summer, from May to around July/August - before the seed pods ripen.
We've been working with lots of volunteers and community groups to pull balsam as it's a task anyone can get involved in and it's certainly a case of many hands make light work!
Cutting / Strimming
An alternative option for controlling Himalayan balsam is to cut them 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 higher the plant will re-grow.
Again it's critical that cutting is only carried out before the seeds form.
We have been using this technique where we have large, monoculture stands of balsam - in these circumstances it is quicker and more efficient than hand pulling.
During the summer months we have conservation volunteer days that you can join in with to pull Himalayan balsam, these are a great fun way to get involved, get outdoors and meet new friends. Alternatively, we can facilitate this activity for existing groups.
Check our events page for details of upcoming conservation events.