English ivy (Hedera helix), a heavy, woody vine with beautiful, dark-green waxy leaves, is believed to have been brought to the New World by European colonists in the 18th century. They likely appreciated its shade tolerance, its versatility as a ground cover and climbing vine, and its rapid growth.
But today, they are classified as an invasive species in many parts of the United States, where they grow quickly and can choke, starve and weaken trees.
If you live in one of those areas, you’ve probably seen them climb tree trunks. And you are probably painfully aware of how difficult it is to eradicate it.
Threat to trees
The vine works its way up the tree and under the bark, holding its roots and branches firmly as it grows. Simply pulling out the ivy will also remove the bark, which serves as vital protection for the tree from insects, diseases, and the elements. In addition, dense ivy leaves can block sunlight from reaching the tree, preventing photosynthesis, reducing the nutrients it can produce.
The weight of the vine weakens the branches and can cause the tree to fall during severe weather, endangering people and property. It is also a host plant for insect pests that can attack the tree, and mosquitoes that can attack you.
Because its stem and vines cling tightly to surfaces via three different methods—aerial roots, tendrils, and a sticky substance called glycosides—English ivy removal must be done carefully to avoid damaging the trees.
How to remove it
Always wear gloves when handling English ivy, because the glycosides will stick to your skin and irritate it. Some people have also reported breathing difficulties when working around the plant; The mask will provide protection. If you suffer from allergies, it is best to have someone else do this task.
Cut the ivy all around the tree, at a height of 3 feet from the ground, using pruners or a hand saw. Then, one by one, carefully separate the separate top of each branch from the bottom, which will still be growing out of the ground.
Next, work your way around the base of the tree and dig up all of the ivy’s roots and remove the plant from the soil. Keep an eye on new growth from any roots you may have missed and pull out new shoots when you see them.
Allow the cut off top of the ivy to remain on the tree. Over the course of about a year, it will die and release its stronghold from under the bark. The wilted foliage will eventually come off.
Protect the walls too
English ivy growing on the side of a brick house threatens to damage the structure. As the plant climbs walls, its tendrils become lodged in cracks or gaps in the mortar, which will weaken if the ivy is left in place. Pulling the chrome down will likely damage the grout as well.
Avoid the temptation to use chemical herbicides, as they may stain the brick. The waxy coating of the leaves protects them from most weed killers anyway.
Instead, start by treating the vine as if it were growing on a tree: cut it back at the point where its trunk meets the wall and remove the lower parts of the soil.
Next, cut each vine as close to the wall as possible, but allow the young roots to remain embedded in the mortar for a few weeks. Once these roots darken and die, use a stiff brush and detergent to scrub them safely.
Be sure to assess any damage caused by the factory and make repairs as soon as possible.
Jessica Damiano writes the award-winning Weekly Dirt newsletter and regular gardening columns for The Associated Press. Sign up here to get weekly gardening tips and tricks delivered to your inbox.