Fighting English Holly In Western Washington

Typically associated with Christmas Time, English holly is becoming a big problem for western Washington forest lands.  English holly, famous for its shiny leaves and red berries, is spreading aggressively, crowding out native plants and damaging wildlife habitat.

Washington State University Extension forester Kevin Zobrist says holly is now one of the region’s most prolific invasive species.

“It’s up there with Himalayan blackberries as one of the most prolific invasives we deal with,” Zobrist noted. “It’s rare that I visit a landowner and we walk through their forest without finding holly.” 

How Did Holly Spread?

Originally planted intentionally more than a century ago, and even promoted in the 1920s as part of a “Holly State” campaign, the shrubs have since taken over parks and forests.  And while the the “Holly State” moniker may have failed, other parts of the campaign were a runaway success.  The wife of a prominent lumber executive and the founder of the Seattle Garden Club, Lillian McEwan recruited school children to plant holly in local parks.  In 1928, Girl Scouts planted 1,500 holly seedlings on Arbor Day in Seattle’s Seward Park.

Similar planting projects took place in other communities. Over a decade, an estimated 30,000 Western Washington children planted holly in their local parks and forests. In addition, birds help spread the seeds, and underground runners form dense colonies. 

Once established, holly is hard to eradicate. “Studies show that left unchecked, holly will spread at an exponential rate,” Zobrist said. “It will completely take over the forest understory.” 

Zobrist says cutting it often makes it worse.  He has to use a special herbicide-injection tool, but it can cost more than $1,500. 

The Fight Continues

Becky Chaney has been fighting holly on her four-acre property near Carnation for about 30 years.

“It’s pretty common in my neighborhood for people to think of holly as being desirable,” said Chaney, who chairs the King County Noxious Weed Control Board and previously worked as an environmental consultant. “Holly is one of those invasives that lingers in the background. By the time you notice them, they’re pervasive and hard to control.”

Through constant vigilance, Chaney has been successful with mechanical removal on her property. Young holly starts are removed by hand. She trims back the branches on established hollies, weakening the trees until she can dig up the taproot.

In Washington, there are no requirements for controlling holly on your property.

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