About broom

Broom species, particularly Spanish, French, and Scotch broom, are significant problems in California due to their aggressive colonization after disturbances such as high-severity fires. They often spread through human activities, including the use of heavy equipment, road maintenance, and land development. Once established, these hardy plants outcompete native vegetation, altering ecosystems and reducing biodiversity.

One of the key reasons for their success is their prolific seed production—each plant can produce over 8,000 seeds, which remain viable in the soil for up to 25 years. This long-lived seed bank makes eradication challenging, as even after removal efforts, new plants can sprout years later. Additionally, broom plants create dense thickets that suppress native plant regeneration, alter soil chemistry by fixing nitrogen, and increase wildfire risk due to their high flammability. These combined factors make broom species a persistent and costly invasive threat in California.

Origin

The broom plants, originally from Europe, were introduced to the United States in 1850 for ornamental use and erosion control. By the early 1900s, they spread along the West Coast, particularly after fires near highways.

Spanish and French broom originate from the Mediterranean region and the Azores, while Scotch broom comes from Central and Southern Europe and Northern Africa. Today, Spanish and French broom are found along the Pacific Coast, from British Columbia to Southern California and Hawaii. Scotch broom, however, is more widespread, thriving along both the Atlantic and Pacific coasts, as well as in Alaska, Idaho, Montana, and Utah.

Why it’s a problem

Three Species of broom in Lake County

Prevent Broom From Entering the Property

  • An important key to managing broom is preventing the spread of it to other properties. Clean and sanitize the tools  with a 10 % bleach solution to prevent it from establishing on other parts of the property or on other’s properties. 

  • French broom may still be offered for sale, under a different common name, so take care to avoid purchasing the species by checking the Latin name of any plants you purchase. 

  • Keep an eye out for new broom seedlings in areas near existing populations and remove them while they are still young before they go to seed. Mulch area thickly to prevent seed germination and re-plants with site-appropriate species that will shade out any future seedlings.

How to remove Broom from your land

  • Hand pulling is the most effective removal method, especially during the wet season when the soil is soft, allowing the entire taproot to be removed. Since broom are perennial plants with deep taproots, removing them entirely is crucial to prevent regrowth.

    For larger, more mature plants, a "weed wrench" may be necessary to extract the roots. Always start by pulling new infestations first before moving on to more established areas. Minimize soil disturbance as much as possible to prevent seeds from germinating from the seed bank.

  • Cutting broom shrubs just above ground level can be an effective control method when timed correctly.

    • Cut Broom in Bloom: The best time to cut is during April–May when the plant is flowering. Exposure to the sun at this stage often kills the plant.

    • Winter Cutting: If cutting in winter, trim the main stem 8–18 inches above ground level and remove all branches. While this won’t kill the plant immediately, it will prevent flowering. The main stem can then be cut again in summer when the heat will finish killing it.

  • For resprouting broom or plants too large to pull, girdling is an effective method. Use a knife or sharp tool to remove a strip of bark around the main stem, severing the vascular cambium. This disrupts the flow of nutrients between the roots and foliage, slowly killing the plant over time.

    • Glyphosate 1.5-2% mixed in water 

      • Apply just as flowers are blooming for most effective control

      • Can apply to the cut stump a few minutes after cutting

    • Triclopyr 50%

      • Can apply to the cut stump a few minutes after cutting or when leaves present

    • Clove Oil

      • Can apply clove oil to the cut stump