Widely planted as a groundcover, English ivy (Hedera helix) has turned out to be one of the most aggressive non-native plants ever seen in the Pacific Northwest. Highly tolerant to shade, ivy grows quickly along streambanks and forests. Combined with an ability to resist dry conditions and to grow during winter months, it simply out-competes native groundcover plants.
However, ivy has a deadly effect on trees by:
- Robbing trees of moisture and nutrients;
- Preventing photosynthesis by blocking sunlight from reaching leaves;
- Adding weight to limbs and trunks, causing them to fall;
- Acting as a reservoir for bacteria that cause leaf scorch, which causes leaves to die.
Any combination of these factors can lead to a decline in tree health in only a few years. However, the good news is that you can do something to prevent it.
Cut ivy vines (but not the tree trunk!) at ground level to kill upper portions. The vines will probably grow back; simply remove them when they appear. While groundcover ivy can be pulled up by hand, it's more easily removed during the wet winter months when the ground is softer.
For more information about ivy removal or protecting trees along Salem's streams, contact:
City of Salem Water Resources
Marion County Master Gardeners
Useful web sites: