Text and photos by Nancy Cleeland
Like rust, English ivy never sleeps. It escapes yards and creeps down embankments and over rocks and up trees all year long. Planted by colonists in the 1700s and still sold in garden centers as a carefree ground cover, this ivy smothers the ground with dense mats and drapes the canopy with heavy, sun-blocking, deadly vegetation.
English ivy (Hedera helix L.) is one of the most destructive invasive plants in our local natural areas, according to the field guide Plant Invaders of Mid-Atlantic Natural Areas, which describes it as “an aggressive invader that threatens all vegetation levels of forested and open areas, growing along the ground as well as into the forest canopy.” Ivy outcompetes vegetation on the ground and trees for water and nutrients, and when it encircles trees, it holds moisture near the bark, encouraging rot.
According to the guide, “An infested tree will exhibit decline for several to many years before it dies. The added weight of vines also makes trees susceptible to blowing over during storms.” Also of note, English ivy only matures when it climbs, and then it produces berries that birds can carry long distances to infest new areas.
But there is some good news: With steady, determined effort over many years, English ivy can be cleared from invaded areas to the point that occasional sweeps are enough to keep it in check.
English ivy’s year-round growth habit makes it easy to spot in winter, when its waxy green leaves stand out from the brown landscape. Ease of spotting is one reason it is often targeted for removal at this time.
On a brisk morning in mid-February, about 30 volunteers gathered at a parking lot near Spout Run for a foray into National Park Service land along the George Washington Parkway, where the ivy was thick. Amy White, an ARMN member and Weed Warrior volunteer with the National Park Service who organized the event, described our priorities—freeing the ivy-choked trees that were still alive. Loppers and saws were the tools of the day; mere garden clippers were no match for vines at least several inches in diameter.
In clearing ivy, one must be careful not to pull the entire length of the vine, which can tear off attached bark and harm the tree even more. The recommended technique is to cut roots around the base or cut an ivy-free band around the trunk, as described on this ARMN web page. Unrooted, the vines will eventually die, turn brown, and disintegrate, allowing the tree to breathe again. The cut ivy can be left behind on branches and logs to dry out, as long as it doesn’t touch the ground to resprout.
It’s important to distinguish between destructive English ivy and beneficial native vines such as native wild grapes (Vitis spp.) and poison ivy (Toxicodendron radicans), which should remain untouched in parks and natural areas.
We spread out, climbed the steep embankments and chose targets from among the many ivy-choked trees. In some cases, the ivy was so thick it resembled a second skin of bark. It can take 15 minutes or more to free a single tree in this state—prying a bit of ivy loose and sawing out a chunk, one at a time. What a great feeling it was to liberate a tree, which seemed to sigh its gratitude.
We worked silently, focused on the task at hand. After a fast two hours, our scheduled time was up. Reluctantly, we packed up our tools and filed back to the parking lot. So many trees were left behind, but we had certainly made a dent in the problem. According to Amy, by morning’s end our group had “saved” about 300 trees. More events will be scheduled this spring.
In contrast, a few days earlier at Gulf Branch Park in north Arlington, a crew of volunteers fanned out and canvassed the ground for any ivy plant that dared poke above the leaf litter. The trees were gloriously free of choking vines. Jen Soles, Arlington County’s Natural Resources Specialist, directed our group along both sides of the stream, where we also spotted and removed a few other early blooming invasive ground plants.
Jen had been Park Naturalist at Gulf Branch for 10 years before her promotion, so she knew the terrain well. She recalled arriving at a park draped with choking ivy and chipping away at the problem over a decade. Volunteers from ARMN and other groups helped battle the vine, cutting it off trees and pulling roots out of the ground. It kept coming back. The game changer came when Arlington began using trained contractors to apply selective herbicides to the roots to prevent regrowth, she said. That combination of boots on the ground and expert application of herbicides eventually created the more natural landscape we see today.
ARMN, National Park Service Weed Warriors, Tree Stewards of Arlington and Alexandria and more local groups clear invasive vines and other destructive non-native plants every weekend. If you’re interested in joining us to liberate a few trees from the deadly choke of ivy, check out ARMN’s Volunteer Opportunities page with a calendar of events.