Himalayan Balsam (Impatiens glandulifera) is an Invasive Non-Native Species (INNS), it originates from the western and central Himalayas and was first brought over to the UK in 1839 as an ornamental plant to decorate Victorian gardens
Shortly after it quickly spread to a wide range of habitats, particularly along riverbanks and in damp woodlands (Tanner and Gange., 2020).
Balsam flowers from June to October, and its seeds are set from August to October. Each plant is able to produce up to 2500 seeds which sit inside explosive seed pods and, when disturbed, are capable of distributing the seeds up to 7 metres away! (Sonal et al., 2016).
It grows in dense monocultures (a large amount of a singular plant, like crops on a farm) which outcompete native vegetation leading to a decline in native plant and insect populations (Pollard et al., 2019)
As it’s an annual plant, once it dies back in autumn this leads to a bare river bank (which would normally be covered with native plants) and so there are no roots which bind the soil together during heavy rain, this leads to soil erosion.
While Balsam is a good source of pollen for pollinators, studies show it can alter the foraging preferences in bee species which results in bees focusing their attention on Balsam and neglecting native species (Lopezaraiza et al., 2008).
Balsam is one of the easiest INNS to remove, its shallow roots and noticeable characteristics make it easy to find and pull up. ‘Balsam bashing’ groups tend to organise around areas which are highly infested.
To remove Balsam:
- Pull up the plant by grasping the stem as close to the root as possible (ensuring it does not snap, leaving the root in the soil)
- Snap or crush the plant close to the root, at the lowest node (the bulge closest to the roots)
- Hang the snapped plant on a tree branch or pile it up, this will dry it out and prevent it from re-rooting.
- If hanging the plant, make sure not to overload the tree branches to prevent them snapping.
- If it is not possible to hang the plant then pile it up on the ground, preferably on a surface where it cannot re-root and in a shallow pile so that it can dry out
Balsam pulling season is over now but look out for Balsam pulling sessions next year between April – June!