Time to Tackle English Holly in Lake Forest Park
Sunday, September 13, 2026
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| A holly-choked understory (left) blocks the sunlight and water native plants need to survive, leaving barren ground beneath. A healthy native forest floor (right) lets light through to support ferns, salal, Oregon grape, and other understory species. |
By Richard Saunders and Ross Baarslag-Benson
Lake Forest Park Tree Board
English holly (Ilex aquifolium), also known as common holly, may look festive, but King County classifies it as a non-regulated Class C noxious weed, meaning removal isn't legally required, but it's officially recognized as invasive and control is strongly encouraged.
The urgency is real: a University of Washington Bothell study at nearby Saint Edward State Park found wild holly populations doubling in area roughly every 5 to 6 years, spreading not only through bird-dispersed berries but also by root shoots and stem layering, which lets individual plants expand into dense thickets (Dick Olmstead, Washington Native Plant Society blog, November 2025).
English holly (Ilex aquifolium), also known as common holly, may look festive, but King County classifies it as a non-regulated Class C noxious weed, meaning removal isn't legally required, but it's officially recognized as invasive and control is strongly encouraged.
The urgency is real: a University of Washington Bothell study at nearby Saint Edward State Park found wild holly populations doubling in area roughly every 5 to 6 years, spreading not only through bird-dispersed berries but also by root shoots and stem layering, which lets individual plants expand into dense thickets (Dick Olmstead, Washington Native Plant Society blog, November 2025).
It's quietly reshaping our forests: as it spreads deep into greenbelts and backyards, its dense evergreen canopy shades out native plants and suppresses the trees and shrubs our ecosystem depends on.
It also carries real risks at home: its berries are toxic to children and pets, its spiny leaves can cause skin irritation or allergic rash, and its pollen can trigger hay-fever-like symptoms.
Removing it: Manual digging is best, remove the entire root system, since leftover roots resprout. For larger specimens (over 6" DBH, diameter at breast height), a City tree permit is required in Lake Forest Park; cut the trunk flush and treat the stump promptly with a systemic herbicide (see the King County English Holly Fact Sheet for guidance).
It also carries real risks at home: its berries are toxic to children and pets, its spiny leaves can cause skin irritation or allergic rash, and its pollen can trigger hay-fever-like symptoms.
Removing it: Manual digging is best, remove the entire root system, since leftover roots resprout. For larger specimens (over 6" DBH, diameter at breast height), a City tree permit is required in Lake Forest Park; cut the trunk flush and treat the stump promptly with a systemic herbicide (see the King County English Holly Fact Sheet for guidance).
Late summer/early fall is the ideal season, and cleared spots make great spots for a native replacement from LFP's Approved Tree List.
Lake Forest Park has long taken tree stewardship seriously. The City has been a Tree City USA for 45 consecutive years. Much of that legacy is thanks to local environmental groups, involved citizens, our all-volunteer Tree Board, which provides community education, organizes planting events, and advises City Council on tree policy, working alongside our staff Urban Forest Planner, a certified arborist who oversees permitting and tree health citywide.
Lake Forest Park has long taken tree stewardship seriously. The City has been a Tree City USA for 45 consecutive years. Much of that legacy is thanks to local environmental groups, involved citizens, our all-volunteer Tree Board, which provides community education, organizes planting events, and advises City Council on tree policy, working alongside our staff Urban Forest Planner, a certified arborist who oversees permitting and tree health citywide.
Together they help implement LFP's tree canopy ordinance (LFPMC Chapter 16.14), which protects significant trees while guiding smart replacement and removal.
Want to learn more, get involved, or ask about a tree on your property? Visit the Tree Board page
Want to learn more, get involved, or ask about a tree on your property? Visit the Tree Board page
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