Scotch Broom - An Alien Invader

Scotch broom is sometimes admired as a beautiful ornamental species. With bright yellow flowers and lush green stems, many people consider it to be attractive. Gardeners take samples from road edges to put in their garden, or take cuttings from their plants to share with fellow gardeners. However, scotch broom is considered a highly invasive non-native plant.

Broom is originally from Eastern Europe and was brought to BC in the 1850’s as a garden ornamental to new immigrants of their homeland. Since then, this seemingly harmless plant has spread dramatically throughout the Coastal areas of BC and is now moving into some areas of the Southern Interior, changing the landscape and its ecology. Broom is a member of the legume family and can form a close relationship with nitrogen fixing bacteria. The ability to access nitrogen helps the plant become established in disturbed areas with poor soil. Broom also acidifies the soil where it grows reducing competition from other plants. It is well adapted to grow in harsh conditions, and aggressively outcompetes native species.

Although it has been known as an aggressive plant on the coast of BC (it is their “knapweed”), the cold winters have held it back from spreading in the interior. But that may be changing as our climate gets warmer. It is also flammable, contributing to the local fire hazard of our region. Broom has escaped cultivation and continues to spread throughout the Central Kootenay. You may have noticed the thickets of bright yellow flowers in Nelson area, Riondel, and Nakusp.

Since broom has no natural enemies in BC, the only way to get rid of it is to remove it yourself. You can do this by pulling small seedlings (less than a pencil width) when the soil is moist. Larger plants must be cut down, preferably in May when the flowers are out but they have not yet gone to seed. It is important to prevent plants from going to seed as this is the major method of spread. Broom does not grow well in shade, so to help prevent older plants growing back, cover the cut stump in plastic to prevent light access. It is also important to remove cut plant material from desirable areas as these old plant parts will release materials that prevent re-establishment of desirable plants.

Added on May 8th, 2007 - Return to Special Features