The Washington State Department of Agriculture is considering adding English ivy (Hedera helix) and Atlantic ivy (Hedera hiberica) to the Noxious Weed Seed and Plant Quarantine.

The rule prohibits the sale and distribution of certain species in Washington due to their invasiveness. The department is currently considering rulemaking, said Scott Brooks, manager of WSDA’s plant services program.

“English ivy and Atlantic ivy are a problem in Western Washington where they have spread into forested areas,” Brooks said. “Both species can climb native trees and eventually kill them.”

English ivy and Atlantic ivy are widespread in Western Washington, he said, with a higher concentration near urban areas and along roads.

“These two species are not native or naturally-occurring,” Brooks said. “In the past, they were popular ornamental plants, but over time escaped cultivation and became established in new areas where they can dominate and outcompete natives.”

“Throughout the entire Pacific Northwest coast, English ivy and Atlantic ivy have been doing immense damage to our landscape,” said Michael Feerer, founder and executive director of the nonprofit Whatcom Million Trees Project. “It kills virtually every tree it climbs up on eventually, shortening the tree life. It’s degrading our forests.”

Feerer estimates millions of dollars of damage per year, affecting thousands of trees. The nonprofit is one of the original petitioners to the state requesting the change.

The project has identified more than 3,200 mature trees in Whatcom County that have ivy climbing up the trunk, and cleared ivy from more than 1,940 trees.

Difficult to control

Control of English ivy and Atlantic ivy “is very difficult and requires a lot of manpower and resources,” Brooks said.

Certain cultivars of English ivy and Atlantic ivy are already Class C noxious weeds in Washington.

“WSDA is considering adding the entire species of Hedera helix and Hedera hiberica to the quarantine, rather than certain cultivars,” Brooks said, citing an example from Oregon. About 15 years ago, Oregon enacted a prohibition on the sale of certain cultivars of English ivy and Atlantic ivy but found that to be difficult to manage. Oregon later updated the rule to prohibit the sale at the species level to avoid confusion.

“WSDA sees a lesson in that and is considering prohibiting the sale all cultivars of English ivy and Atlantic ivy,” Brooks said.

Impact to nurseries

English ivy and Atlantic ivy do not appear to be heavily sold in the nursery trade or installed as a landscape plant, Brooks said.

“As part the rulemaking process, WSDA is required to assess the impact to small businesses if they could no longer sell, grow or install these species,” Brooks said. “That assessment is happening now.”

But Feerer said the plants are sold in box stores and nursery wholesalers.

“If you look back at home landscaping books 15, 20, 30 years ago, they all tout the benefits of English ivy because it grows so rapidly,” he said. “But no one back then realized the impact it has on trees … There’s more of an understanding of that now, and more of a need to be cognizant of what’s happening to our trees due to our new climate era we are in.”

Because ivy is so aggressive, nurseries might have a slight economic gain with a ban as they pivot to different ground covers, he said.