‘Balsam Bashers’ needed in Rossmore Park


Would you like to learn about, and perhaps even help stop the spread of invasive plants in Monaghan? If so, read on. Invasive species are those which are not native to a specific location and that tend to spread rapidly causing damage to other more native varieties. Dermot McNally tells us about two of the common invasive species found in Rossmore Park – Himalayan Balsam and Rhododendron.

 Dermot McNally

Himalayan Balsam is an attractive annual flowering plant with a sweet smell. It can form dense stands and can reach 2 – 3m in height. The stem of the plant is smooth, hairless and hollow. The flowers of this plant can vary in colour but are usually shades of pink. Between June to October each plant can flower and produce up to 800 seeds which can be dispersed widely as the plant pods shoot their seeds up to 7m away. Seeds can remain dormant in the ground for 2 years.

Rhododendron is an extremely hardy and large evergreen shrub (growing up to 8m tall) with flowers of various colours. Its popularity, adaptability to Irish climate and soils, shade tolerance, along with its highly successful and multiple methods of reproduction and dispersal, means that it has spread rapidly. It was originally planted as an ornamental plant in the 18th Century and, in Rossmore, is found along the banks of the Castle Lake, adjacent to the head of the wooden giant Roddy Den Drum.

Roddy Den Drum in Rossmore Park


Because of the speed and height of Himalayan Balsam’s growth, it can quickly shade out native plants and saplings reducing native biodiversity. From October onwards, the plants die back leaving the soil, especially along rivers, much more exposed to erosion. A further impact is that the nectar found in Balsam is more attractive to bumblebees resulting in less pollination of our native species. Rhododendron forms dense impenetrable thickets and is thought to be toxic to both mammals and invertebrates. The deep shadow cast by the plants and toxic leaf litter produces a dark sterile environment, which suppresses regeneration of other species.


Himalayan Balsam can be removed quite safely and simply by pulling up the entire plant, root included. Gripping lower down on the plant avoids snapping the stalk and ensures the plant cannot regrow. The plants can be piled and crushed underfoot to prevent any residual development of flowering heads. Long sleeves and gloves are all that are needed to perform the task. It is best to undertake the removal before seed pods form as disturbance at this later stage can cause the seed pod to shoot its seeds. Large scale Rhododendron removal involves cutting all standing rhododendron in the first instance and following up to treat stumps or using machinery to dig out the roots.

Thankfully there is something that volunteers can do: small plants can be easily pulled by hand and each plant removed is a help. This Saturday, the focus will be on tackling Himalayan Balsam. Ask not what Rossmore Park can do for you…

If you are interested in taking an hour to learn to identify and help eradicate Balsam from Rossmore, then head for the Park this Saturday morning at 10.30, see Notices for further details.

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