Ivy is not a parasite and it can provide significant ecological benefits. We look at the facts about this prolific climber.
Many people believe the climbing plant ivy (Hedera helix) is harmful to trees and should be removed because it strangles them. This is essentially a misconception as ivy is generally harmless to the trees themselves (it is not parasitic) and has numerous other benefits.
Ivy is our only native evergreen climbing plant. Its growth on tree trunks provides valuable shelter and habitat for nesting birds and roosting bats beneath the leaves and stems, the flowers are a good source of nectar for insects later in the season and the birds feed on the high-protein berries during the winter. Overall it is valuable to biodiversity and should normally be allowed to grow unchecked.
So what are the disadvantages of ivy in trees? Large masses of ivy in the crown of a tree may overburden it and make the branches or stems more likely to fail during high winds. The evergreen foliage may compete with the tree for light in extreme cases or, if a tree is already in poor health, ivy may sometimes hide defects on a tree and make inspection more difficult.
The benefits of ivy generally outweigh its drawbacks but if it does need to be removed, clearing a metre or so section of the lower trunk is normally sufficient, leaving the upper parts of the plant to die away naturally.