Vectors of Spread:
General: Scotch Broom can be identified by its small, bright, pea-like yellow flowers and its rigid woody stems.
Flowers: Pea-like, bright yellow and often with a red center. The flowers are usually 2 cm long and have 5 petals.
Stem: Scotch Broom stems are rigid and woody and range from green to brownish-green. Young branches have 5 green hairy ridges, but they become smooth as they mature. Mature plants can be 1-3 m tall.
Leaves: Lower leaves are stalked and composed of 3 leaflets, while upper leaves are un-stalked. The leaves may fall off early in the year, leaving the stems bare.
Seeds: Scotch Broom flowers mature to form flattened seedpods (legume looking) that change from bright green to brown or black before they dry out and split. Each pod contains between 5-12 seeds.
Gorse (Ulex europaeus) is a (very!) thorny shrub with inch-long sharp spines that may grow up to 1.8 m tall. The flowers, similarly to Scotch Broom, are yellow and pea-like; however the flowers are around 0.8 cm long and cluster on the ends of the branches.
St. John’s Wort (Hypericum perforatum) is a perennial that grows to about 1 m in height. It has showy, bright yellow flowers with 5 petals that turn rusty red when they mature. It prefers dry, sandy soils and full sun.
Spanish Broom (Spartium junceum) is another invasive Broom plant with yellow flowers. You can spot the difference by their stems: Spanish Broom stems are round, whereas Scotch Broom stems are ridged. Spanish Broom also flowers later in the year.
Habitat and Origin
It was brought to North America from Scotland as a garden ornamental by Captain Walter Grant and planted on Vancouver Island in Sooke. Amazingly, Captain Grant only brought over 3 Scotch Broom seeds with him in the 1850’s and the plant has managed to spread and thrive across Vancouver Island, the Lower Mainland and Squamish at an incredible rate.
Scotch Broom grows in open, disturbed sites at low elevations and can be found along roads, railway lines and utility right-of-ways. It grows in areas with well-drained, sandy soils.
Propagation and Vectors of Spread
Scotch Broom can spread by seed as well as by lateral bud growth. The yellow flowers mature to form flattened seedpods that change from bright green to brown or black before they dry out and split. Each pod contains between 5-12 seeds. Mature plants can produce up to 3,500 seedpods, and each seed can stay viable in the soil for up to 60 years.
Scotch Broom is an extremely aggressive spreader and can quickly cover fields, meadows and deforested areas. It thrives in sunlight but can also grow in shady areas.
Economic and Ecological Impacts
- Threatens biodiversity and disrupts the food chain by altering the nitrogen composition of the soil, which in turn can alter the potential composition of the surrounding area
- Displaces native plant and animal species
- Contains toxins that can harm animal health
- Limits the movement of large animals due to the size and density of the thickets
- Dense thickets also act as fuel loads, increasing the chance of forest fires
- Obstructs sight lines on roads, railways and utility right-of-ways, resulting in increased maintenance costs for removal
- Grows quickly in clear-cut forested areas, making the potential for forest re-growth extremely difficult, or nearly impossible
- Takes over farmlands:
- Once the plant roots, it can become a tripping hazard for horses and livestock within that enclosure
- Toxic to animals
What Can I Do?
The best approach to controlling the spread of Scotch Broom is PREVENTION.
Learn to identify Scotch Broom: use the images presented in this profile page.
What to do if you spot it: You can report any Scotch Broom sighting by clicking here.
- Regularly monitor properties for weed infestations.
- Ensure soil and gravel is uncontaminated before transport.
- Quickly re-vegetate disturbed areas with fast-growing competitive, native plants can limit growth of Scotch Broom and is a fundamental tool to limit it.
- Minimize soil disturbance in area surrounding infestation.
- Ensure plants (particularly flowering heads or root fragments) are bagged or covered to prevent spread during transport to designated disposal sites (e.g. landfill).
- Plant Scotch Broom in a garden, no matter how well-contained its enclosure may seem.
- Move soil that has been contaminated with Scotch Broom.
- Unload, park, or store equipment or vehicles in infested areas; remove plant material from any equipment, vehicles, or clothing used in such areas and wash equipment and vehicles at designated cleaning sites before leaving infested areas.
- Mow or weed-whack Scotch Broom plants, as the fragments can propagate as new colonies. Frequent mowing may also accelerate shoot development, leading plants to spread laterally from the parent plant
Mechanical Control: Small seedlings (less than a pencil width) can be hand-pulled when the soil is moist. Larger plants must be cut down at the base of the stem before they begin to flower.
Due to Scotch Broom’s need of sunlight to photosynthesize, covering the newly-cut stem with soil, moss or plastic will help prevent regrowth.
Chemical Control: Commonly-used herbicides include triclopyr, imazapyr, aminopyralid and glyphosate, applied alone or in combination with 2,4-D. Herbicides can be applied from spring to late summer using selective spot spraying, basal stem injection, or cut surface application.
We recommend that any herbicide application is carried out by a person holding a valid BC Pesticide Applicator Certificate. Before selecting and applying herbicides, you must review and follow herbicide labels and application rates; municipal, regional, provincial and federal laws and regulations; species-specific treatment recommendations, and site-specific goals and objectives.
Biological Control: Seed-feeding beetles have been used in Washington State and have moved north along with two other agents that are not yet in BC, but are close to the Canada-US border. Grazing goats and chicken have been used in places such as Vancouver Island, and have been shown to reduce infestations.
Broom Busters, About Broom, http://www.broombusters.org/about-broom/
Invasive Species Council of BC, Scotch Broom Info Page, https://bcinvasives.ca/invasive-species/identify/invasive-plants/scotch-broom
Invasive Species Council of BC, TIPS Factsheet, https://bcinvasives.ca/documents/Scotch_Broom_TIPS_Final_08_06_2014.pdf
Nature Conservancy of Canada, Scotch Broom, http://www.natureconservancy.ca/en/what-we-do/resource-centre/invasive-species/scotch-broom.html
Washington State Noxious Weed Control Board, Scotch Broom, https://www.nwcb.wa.gov/weeds/scotch-broom