Some gardeners like the look of ivy twining up a tree trunk. However, vines that twine too far can be bad news for the tree, according to Sharon Yiesla, plant knowledge specialist at The Morton Arboretum in Lisle.
“A few vine stems on a tree’s trunk are mostly harmless,” Yiesla said. They cling to the bark with fine, hairlike rootlets but don’t penetrate the wood.
However, “if a vine grows up into the branches, it can crowd out the tree’s leaves,” she said. “The vine’s leaves may block the sunlight that the tree’s leaves need to manufacture food.” Eventually, a tangle of vines can weigh enough to break tree branches.
A large vine also will compete with the tree. “The vine has its own root system, which is absorbing water and nutrients from the same soil as the tree’s roots,” she said. Over time, competing with a vigorous vine may weaken a tree, making it more susceptible to drought, pests and diseases.
In city and suburban yards, vines that climb trees are usually woody ground covers such as English ivy and euonymus. Hardy and shade-tolerant, they often are planted beneath trees where there isn’t enough sun for grass to thrive. They spread readily to cover shady areas. Unfortunately, they also can spread rapidly up into the trees, grabbing onto the bark crevices. Boston ivy, frequently planted to cover walls, also can grow up trees.
Two native vines that often cover trees in natural woods as well as gardens are Virginia creeper and poison ivy. “That’s why you should always identify the plant before you remove a vine,” Yiesla said. “You don’t want to accidently tangle with poison ivy.” The Plant Clinic (mortonarb.org/plantadvice) can help with plant identification.
If multiple small vines are growing up a tree’s trunk, simply peel them off the bark and yank the roots up by the stems. The roots will come up more easily if the soil is moist.
“Pulling the plants up with their roots is safer and more effective than using a weed killer spray,” Yiesla said. “The herbicide in the spray might harm the tree or other plants.”
In a ground cover bed, try to remove all plants within 6 to 8 inches of the tree’s trunk. Check every few months, and remove any vines that encroach again.
When vines are growing all the way up into a tree’s branches, cut the stems at about waist height. Pull up the lower portion with the roots. Gently try to pull the upper portion out of the tree, but if it doesn’t come easily, don’t force it and risk breaking any branches. “Leave the vine to die and dry out,” Yiesla said. “When it’s brittle, it will most likely fall down by itself.”
Sometimes you’ll find an older vine with a tough, stiff, woody stem that may be larger than your finger and deeply attached to the trunk. “Don’t try to tear it off,” she said. “That might damage the tree bark.” Instead, cut it at the base with a sharp pair of loppers or a pruning saw, being careful not to harm the tree’s bark. Leave the vine attached to the trunk, and let it die on its own.
Digging up such a big vine’s stump could be difficult and might damage the tree’s adjacent roots. Instead, to keep it from resprouting, apply a systemic herbicide to the cut surface of the stump to kill the root system. Consult the Plant Clinic to choose an appropriate product and get advice on applying it safely.
“Keep vines under control on a regular basis, so they never become a problem for your trees,” Yiesla said.
For tree and plant advice, contact the Plant Clinic at The Morton Arboretum (mortonarb.org/plantadvice or [email protected]). Beth Botts is a staff writer at the Arboretum.