What is Himalayan balsam?
Himalayan balsam (Impatiens glandulifera) is an invasive, non-native weed. Native to the Himalayas, it was introduced to the UK as a garden plant in 1939, but it quickly spread into the countryside. It’s typically found growing along moving water courses such as canals and riverbanks. Himalayan balsam is extremely vigorous and spreads quickly, out-competing native plants. Its flowers are loved by bees, and because of this it produces an abundance of seedpods, which explode, dispersing up to 800 seeds per plant. Himalayan balsam seeds often land in moving water, up to 4m from its parent plant, aiding further dispersal.
How to identify Himalayan balsam
Growing to a height of around 2.5m, Himalayan balsam is now the tallest annual plant in the UK. It bears large pink-purple flowers and light green, red-tipped toothed leaves and a reddish stem.
Is Himalayan balsam a problem?
Himalayan balsam spreads quickly and grows in dense patches. Its height, ease of spread and density of growth, along with its ability to grow in low light levels, means it can quickly out-compete native plants, many of which have important ecological benefits to specific insects. What’s more, because Himalayan balsam is so popular with bees, it’s thought that other plants may receive less pollination as a result. In many areas the whole ecological balance of the landscape has been altered by Himalayan balsam, and as such it’s regarded a huge problem by ecologists.
Is growing Himalayan balsam illegal?
Himalayan balsam is listed on Schedule 9 of the Wildlife and Countryside Act in England and Wales. It’s therefore an offence to plant or otherwise cause it to grow in the wild. It’s not an offence to grow Himalayan balsam in gardens but you must not let it escape into the wild. However, because it spreads so easily, it’s almost impossible to prevent it from spreading outside your garden. For this reason, we don’t recommend Himalayan balsam as a garden plant.
Removing Himalayan balsam
Himalayan balsam is a shallow-rooted annual, so is relatively easy to control, but you must not let it set seed. Simply pull up plants before they set seed, and keep checking back every few weeks to ensure no more plants have germinated. Larger areas can be strimmed regularly, again, providing this is done before any plants have set seed.
With regular checking and removal of new seedlings, it’s possible to completely eradicate Himalayan balsam within three years. Compost the plant material unless seeds have developed, if seedpods are present it’s better to burn the material.