Himalayan Balsam – Northern Ireland
If there was a Most Wanted list for plants (or maybe that should be most un-wanted) then Himalayan Balsam would surely be in the top 10. Native to the western reaches of the Himalayas, it was, as with almost all invasive species, originally brought here as a humble garden plant.
Active from spring to autumn, the optimum time to treat Himalayan Balsam is early summer before the plant can seed. Growing in thick ‘stands’ that over-shadow native plants and grasses, it produces a high level of nectar, making it an attractive proposition for bees. This leads to less pollination of native species, and a rapid annexation of the area by Himalayan Balsam. From October, the Himalayan Balsam’s presence reduces, leaving soil exposed to erosion in the absence of the native species.
Himalayan Balsam is also known as Indian Balsam, Jumping Jack, and Policeman’s Helmet, and its natural habitat is gardens, allotments, river banks, and brownfield sites.
How to spot Himalayan Balsam
So, what does Himalayan Balsam look like? Although the flowers (June to October) can vary in colour, they are predominantly pink, purple, and white. In fact, at first glance it’s easy to see why this attractive-looking plant was transported from the mountain slopes. Tall, at between 2m and 3m, the plant’s purple stem is silky smooth, hollow, and easily broken. The large leaves have serrated edges.
How does Himalayan Balsam spread?
One word…seeds! When the flowers mature and dry out it leads to the creation of delicate seed capsules. The slightest touch is all that’s required for these capsules to explode, catapulting seeds more than 20-feet from the parent plant. A single plant can produce close to 800 seeds in a season. As if that wasn’t enough, seeds can also be dispersed by contact with humans or animals, and by water.
How to control Himalayan Balsam
Japanese Knotweed Management offers a survey service that will quantify the extent of the problem and provide a long-term solution. There are traditionally two methods of dealing with Himalayan Balsam, Non-Chemical and Chemical. The former is the option of choice for most, involving the pulling or cutting of plants before they have a chance to flower. In many cases, however, digging is required for a minimum of two years as seeds are sustainable for that period of time.
If Non-Chemical control is not possible, chemical treatments can be used (following permission from The Environment Agency is used on riverbanks).