Himalayan Balsam An Explosive Spreader
Himalayan balsam (Impatiens glandulifera) also known as policeman’s helmet, is native to the western Himalayas. This annual herbaceous plant was originally introduced to Canada as a garden ornamental. It has escaped from people’s yards and is now found in nearly all the provinces. Himalayan balsam is intolerant of frost and drought. It wilts quickly without water and will not survive a long drought. It needs more water than some invasive plants. It is often found in riparian areas but can be found in disturbed areas and woodlands. It grows in dense monocultures. It can grow up to 3 metres high. Himalayan balsam spreads by seed. Each plant produces up to 800 seeds. The seed pods explode open when mature shooting the seeds up to 5 metres from the plant. The seeds stay in the seed bank for about 18 months. The purple to reddish stems are hollow. The flowers are pink, almost orchid like and some say look like an English policeman’s helmet. The leaves are toothed and 5 to 23 centimeters long. It has a shallow root system.
Biodiversity is important. Himalayan balsam limits habitat and nutrient availability. It shades out native plants. It draws pollinators away from other plants. It spreads quickly and outcompetes native plants. All these things reduce biodiversity. It replaces native perennial plants along stream banks which leads to soil erosion. Soil erosion increases the risk of flooding.
Control of Himalayan balsam can be accomplished in 2 years if you stop all the seed from reaching the soil. Infestations can be controlled by hand pulling. Pulling before there is seed is your best option. You don’t want the seed pods exploding while you are pulling the plants. If you can’t pull the plants before the seed is set, you can put a bag over the plant to stop the seed from spreading while you pull. Bag the plants and take them to the landfill once pulled. Mowing or cutting is effective but you must cut the plant below the lowest node to prevent regeneration. Chemical treatment is effective, but you must follow the instructions on the label. As Himalayan balsam is often found near water it is especially important to follow the most stringent guidelines for the use of herbicides. If you have Himalayan balsam in your flower garden, please don’t let it go to seed and don’t share it with your friends. It can cause a lot of problems if it escapes.
Red columbine (Aquilegia formosa) is a B.C. native that is a great alternative to Himalayan balsam. Red columbine flowers attract hummingbirds, butterflies and bees and the dry seed heads attract finches and other small birds. For more information please contact the Boundary Invasive Species Society 250-446-2232, firstname.lastname@example.org, www.boundaryinvasives.com and on Facebook.