Bright blooms are unwelcomed guests

— image credit:
by Laurel Moulton
and Cathy Lucero

It’s July and peninsula roadsides are blazing with the yellow flowers of scotch broom. But scotch broom (Cytisus scoparius) isn’t a natural part of our roadside scenery. Brought to Pacific Northwest gardens in the 1800s, it was later planted to reduce erosion on highways. Scotch broom has since escaped into the wild and become one of the most iconic noxious weeds in the Pacific Northwest.


As soon as scotch broom flowers open, the Clallam County Noxious Control Weed Program is inundated with calls from concerned citizens wondering what they can do to get rid of this weed.


It’s always best to do something as soon as possible, before the problem gets too big. In the spring smaller plants are easy to pull by hand and larger ones can be removed using a tool called a Weed Wrench. The Noxious Weed Control Program can provide specialized control advice if there is too much broom to pull by hand. Over the years a significant seed bank can build up in the soil, allowing new plants to sprout even after larger plants are long gone. Scotch broom control is a long-term commitment with a rewarding outcome.


Because scotch broom is so prevalent and because the Noxious Weed Control Program is required by law to prioritize and focus its limited resources on less widespread invaders, scotch broom is listed as a “selected Class B” noxious weed, meaning it is only required to be controlled in specific high risk locations within the county. This includes places like quarries where seeds are likely to be moved around to start new infestations. In addition to requiring scotch broom control in high risk locations, the Noxious Weed Control Program has enlisted specialized insect predators that eat broom seeds.


But what is wrong with having this brightly flowered, European traveler? Scotch broom is a hardy survivor.

It makes lots of long-lived seeds, up to 12,000 or more per year that can survive for well over 50 years in the soil. But its most important weapon is the special bacteria in its roots that help it to make its own fertilizer virtually out of thin air! This ability, called nitrogen fixing, is common to all members of the pea family and it allows scotch broom to quickly take advantage of disturbed areas even with poor soils. The changes that scotch broom causes to the soil where it grows stunt the growth of nearby plants, allowing it to gain a foothold.


Unimpeded, scotch broom grows densely and more quickly than native plants or commercially planted tree seedlings. Indeed, experts claim that scotch broom accounts for forest production losses exceeding a whopping $1 million annually in Washington. Scotch broom infestations have tended to be worst in western Clallam County, likely spread inadvertently by equipment and gravel infested with broom seeds.

Unmanaged, broom easily can overrun pastures, sharply reducing grazing and hay production.


The past few years have seen the yellow invasion spreading farther into Sequim. There we’re likely to see some other more common, everyday impacts. As scotch broom infestations grow, many people experience increased allergies that are enhanced by the strong fragrance of scotch broom flowers. Also, scotch broom contains volatile oils that burn readily and there have been concerns about increased fire risks during dry summers.


But this unwanted march of scotch broom across the county can be halted and reversed if more people are willing to get involved. No one person or group can do it all. But broom has been pushed back successfully wherever there has been concerted and sustained effort by county chain gangs, volunteer groups and private citizens. It can be as simple as pulling out one plant every day on your daily walk or getting together with a couple of neighbors to tackle bigger patches. Adopt a county road! What a great way to exercise and reduce stress!


Call the Noxious Weed Control office at 417-2442 for Weed Wrench loans or for more information about controlling scotch broom and other noxious invasive weeds. A $50 refundable deposit is required for each Weed Wrench at the time of pick- up.


Cathy Lucero is the program coordinator and Laurel Moulton is a field inspector and crew leader for the Clallam County Noxious Weeds group.


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