English ivy (Hedera helix) is a woody, evergreen, perennial vine commonly seen in urban and suburban forests in King County. It was first introduced in the United States by European settlers as ornamental plants. Since then, it has spread throughout various regions across the country, including King County. There are four cultivars of English ivy (Hedera helix) that are listed as a non-regulated Class C noxious weed in King County. They are Baltica, Pittsburgh, Star, and Hibernica. Although landowners are not legally required to control these plants, KCD strongly recommends controlling, or at least containing them, as well as discourages planting them.
English ivy vines have tendencies to spread horizontally and climb vertically. They don’t directly poison trees, but do negatively affect tree health and increase the likelihood of the tree becoming hazardous to surrounding areas. The thick vines decrease light exposure and make trees vulnerable to tree bark disease and rot. Physically speaking, the sheer mass and surface area that English ivy adds to a tree can make it more susceptible to falling over during high winds.
To contain English ivy and promote tree health, KCD recommends creating a survival ring. Although it may be tempting to remove ivy by pulling it off of a tree, KCD advises against that practice due to the likelihood of potentially damaging the tree or creating hazardous falling debris.
First, to remove the ivy from the tree and its surrounding area:
- At about shoulder height, cut the ivy around the tree (making a ring), severing its connection to the roots.
- Strip the ivy down from the ring that was initially cut. Clear and remove the ivy within a 5 to 10 feet foot radius of the tree to prevent regrowth back up the tree.
- Make sure ivy roots are removed by cutting and pulling them out.
Now that you have the survival ring created, see how to deal with the ivy mass by creating a compost raft.
Related Information from external sources
King County Noxious Weeds English Ivy Information Page
King County Noxious Weeds English Ivy Fact Sheet (PDF)
King County Department of Natural Resources Ivy Control Best Management Practices (PDF)
Green Seattle Partnership Forest Stewards Resource Guide
Program Coordinator, Urban Riparian Habitat Stewardship
O: 425-282-1919 – C: 425-773-8017
Ashley joined KCD in December 2017 with a background in stream restoration and environmental education. Native to Washington, Ashley grew up in Kent and later moved to Bellingham to attend Western Washington University, where she earned a Bachelor of Science degree in Environmental Science with an emphasis in marine ecology. Outside of work, Ashley enjoys hiking, biking, traveling, and caring for her pets.