Jill Severn’s Gardening Column

A civics lesson about English Ivy

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An opinionated reader writes that “the geologic record suggests to me that all species are initially ‘invasive’ and that all species eventually become extinct. Himalayan blackberries, English ivy, mammoths, Homo sapiens.”

That’s not a cheery thought. But it represents one extreme of a spectrum of opinion about the many non-native species that harm or crowd out the natives. Some people are alarmed about all invasives; others want to make exceptions for invasives they like; still others, like our opinionated writer, just shrug it all off.

But even the shrug-it-all-off people will likely find it hard to deny that English ivy – a non-native invader – is a bad actor that kills the trees it climbs. Ivy also carpets the forest floor, creating a ground-covering mat so thick young trees often can’t get enough light to germinate, and ferns and other forest understory struggle to grow. In urban areas where it spreads as a rampant ground cover, it’s also prime habitat for rats and other rodents.

English Ivy was brought to North America by European or English settlers in the 18th century. It took over 200 hundred years for us to figure out it was a problem.

Raymond Willard, State Roadside Landscape Asset Manager at the Washington State Department of Transportation (WSDOT), writes that they “used ivy extensively as ground cover in Western Washington urban interstate roadside settings throughout 1970-80 and into the early 1990s.”

“If we had today's knowledge and experience, we would clearly not have planted Hedera helix in our Western Washington cities… If we had the resources, we would begin systematic removal and replacement of ivy plantings in Western Washington. In Olympia along I-5 our maintenance workers have to spend weeks per year manually cutting and removing overhanging ivy growth along retaining walls at the edge of high-speed traffic.”

“If we had only known” is a common refrain about invasives.

There has been a state Noxious Weed Control Board since 1970, but it for many years it mostly focused on ranchers and farmers’ need to control weeds that affected crops or livestock. (If you want to know what they have to say about English Ivy, see the .PDF file attached to this column.)

The state’s Invasive Species Council wasn’t created until 2006 to address both plant and animal invasives.

The state’s Weed Board decides which plants to list as noxious (which means “harmful,” not necessarily poisonous), and to classify them. The three classifications include:

  • Class A weeds (or plants) that are mostly new in Washington, and still rare enough that there is hope they can be completely eradicated. Landowners are required to get rid of them, root and branch. All Class A weeds are on a statewide quarantine list, and their sale or distribution is prohibited.
  • Class B weeds are widespread in some parts of the state, but absent in others. An example is scotch broom, which is widespread in Western Washington, but has mostly been cut off at the pass and kept out of eastern Washington. Landowners may be required to get rid of it in some counties, but not in the counties where total eradication is impossible.
  • Class C weeds have been here so long and are so widespread we can never get rid of them. English ivy is one of them. Landowners are generally not required to control them unless they are a threat to agriculture or to sensitive places such as riparian areas or natural preserves.

But ivy is so damaging – especially in parks and local forests – we might argue with that. In Squaxin (formerly Priest Point) Park, the fight against ivy is a Sisyphean task, requiring zillions of staff and volunteer hours over many years, and there is no end in sight for this struggle.

It’s up to local county weed boards to enforce the weed laws. Enforcement varies widely from one county to another. In Thurston County, the local board doesn’t even include English ivy on its noxious weed list. On the phone, a representative says they consider it just “an annoying weed” that is not a priority for any action.

As in many science-related fields, there is still ample room for opinion to play a role in decision-making.

And here’s what makes this problem so intractable: When ornamental English ivy plantings are allowed to bloom and make berries, birds eat them and then distribute them far and wide when they poop.

So this was a long road to get to these two points:

  • If you have ivy on your trees, get it off. You don’t have to climb the tree; just cut it off a couple of feet high, and cut it again about six feet high. Strip out what’s between the two cuts. Job done. But watch it, and don’t let it regrow.
  • If you have ivy growing anywhere else, either get rid of it (an arduous task, but at least it doesn’t have thorns), or cut off all the buds and flowers now, and never, ever let them become berries.

We wish this message had been delivered by our local Thurston County Weed Board. We might never be able to eradicate English ivy, but public education and prevention of berry production would help slow it down.

Jill Severn writes from her home in Olympia, where she grows vegetables, flowers and a small flock of chickens. She loves conversation among gardeners. Start one by emailing her at  jill@theJOLTnews.com

Comments

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  • AugieH

    Reminiscent of kudzu, "the vine that ate the South."

    Friday, October 7, 2022 Report this

  • JulesJames

    So when do the berries ripen? And do these berries alway grow up high? Or should we be looking in the ground cover?

    Friday, October 7, 2022 Report this

  • AugieH

    It wasn't noted in the article that the Himalayan Blackberry is a Class C noxious weed.

    Saturday, October 8, 2022 Report this

  • FirstOtter

    An additional reason to destroy ivy is that rats just love it. Not to eat...to live under.

    Tuesday, October 18, 2022 Report this