Tough, hardy, shade-tolerant English ivy seems like the perfect groundcover. But if allowed to spread, it can blanket the area and climb into trees and onto buildings. Ivy clings to walls and tree trunks with aerial roots. These roots penetrate bark and find chinks in mortar and siding. The vines hold moisture against a tree or building, potentially leading to problems with rot.
If you can only do one thing to keep ivy under control, keep it from growing up trees. Cut vines that are beginning to grow upwards and keep a space clear of ivy around the base of the tree. When ivy grows upwards, it is triggered to flower and produce fruits. Birds disperse the fruits and ivy plants become established in new places.
If a tree is already shrouded in ivy vines, clear a 1- or 2-foot section all the way around the tree trunk at about chest height. You'll need to use clippers, loppers or even a small saw to cut through the vines depending on their thickness. Be very careful not to cut into the bark of the tree. Pull or pry the vines off that small section. Leave the vines above the cleared space to die and do not try to pull them off the tree. Pulling on them could damage the tree's bark. As the vines die over 1-2 years they will gradually dry up and fall off the tree. Below the cleared area, spray the vines with a Roundup® Poison Ivy Plus Tough Brush Killer product. Vines can be sprayed in early spring when new ivy leaves are expanding and before other plants have leafed out. Avoid soaking the bark of the tree as some damage could occur. Roundup Poison Ivy Plus Tough Brush Killer products contain an ingredient to help penetrate the waxy coating on ivy leaves and could penetrate the bark of young trees or damaged bark of older trees. It can also help to scar the leaves around the base of the tree with a weed whacker before spraying.
Use the same spray technique described above for ivy growing on the ground. Ivy has shallow roots and it's not hard to pull up the vines. Dense populations or old stands of English ivy can be very difficult to control with herbicides. Repeat applications may be necessary to attain acceptable levels of control. Mats of ivy can be pulled or pried up using a shovel and rolled up like a carpet. Ivy can also be smothered by placing a thick layer of newspaper or cardboard over it and a thick layer of mulch. Monitor treated areas for any re-sprouts.
If you use an herbicide or pull up ivy on the ground, you can replace it with another, less aggressive groundcover. Pennsylvania sedge, wild ginger (shown in picture), partridge berry, Christmas fern or Allegheny spurge are just a few great native groundcovers that could be used in place of English ivy.
Article by Sylvan Kaufman. Dr. Kaufman is a writer of popular scientific and gardening articles. She is also an ecological consultant.