The Himalayan Balsam (Impatiens glandulifera ) is a very pretty but invasive plant species and during the summer months you will see it bordering riverbanks, canals and damp ditches. In July, beautiful, orchid-like flowers, mostly purple or pink but occasionally white, cover its lush green leaves.
It was introduced into the UK in 1839 as an exotic greenhouse plant. But it quickly escaped and now thrives along river and canal banks and damp ditches.
The Himalayan Balsam
What problems does it create?
It crowds out native plant species
By growing in thick, dense bushes that can reach 3 meters tall, light cannot get through to the ground and native species are crowded out.
Unlike many native riverbank plants, the Himalayan Balsam is an annual plant and so both the plant and its shallow roots die back over winter. This leaves large areas of riverbank without roots to hold the soil together causing riverbank erosion, particularly in high water conditions and during winter floods.
How does it spread?
Each plant can produce up to 800 seeds and it has a very clever projectile mechanism for releasing them. The seed pods literally explode open when touched or brushed against, propelling the seeds for up to seven meters away and creating dense coverage very quickly.
Once established along a river bank the seeds are carried further downriver by the water and can germinate up to two years later.
How to spot it and what to do when you find it.
Pull Snap Stomp
The Inland Waterways Association poster above, encourages walkers to pull up a few flowering Himalayan Balsam plants during their walk. To do this, grip individual plants at the base and pull, snap the root off and leave them in a pile away from the path to rot down. If you create a big pile, then stomp on it to speed up the rotting down process. I have found it growing in dense bushes beside rivers and ditches while out walking and kayaking and have pulled, snapped and stomped a few.
Once the seeds have started to develop, don’t touch the plants or you will spread the seeds to other areas.
The following advice is from The Inland Waterways Association
- Pull – Check our Himalayan Balsam identification guide to be certain that it is Himalayan balsam and then pull up individual balsam stems – they pull up very easily,
- Snap – break off the root below the lowest growing node,
- Stomp – Put into a small pile to rot down, away from the path. Bigger piles can be stamped on to assist the rotting process – small children love doing this and it makes a great popping sound!