Is ivy killing my tree?

Ivy has its own roots in the ground and uses the tree only for support. It does not draw sap, it does not throttle the trunk, and a vigorous tree with ivy on it usually stays a vigorous tree with ivy on it. It is also one of the most valuable wildlife plants in Britain — late nectar when almost nothing else flowers, winter berries, roosting and nesting cover, and hibernation sites. That is worth weighing before reaching for a saw.

What you'll need

• A pruning saw or loppers
• Gloves
• A chisel (optional)

Step by step

1. Establish that ivy is not a parasite.It roots in the soil and its stem-roots are adhesive holdfasts, not feeding roots. It takes no water or nutrients from the tree. The competition it does create is at ground level, for soil moisture, and on a mature tree that is minor.
2. Judge how far into the crown it has gone.Ivy confined to the trunk is doing very little. Ivy that has spread through the branches and is carrying its own dense evergreen canopy adds substantial weight and windsail, particularly in winter storms when a deciduous tree would otherwise be bare. That is the real mechanism of harm.
3. Assess the tree's own health first.A strong healthy tree tolerates ivy indefinitely. A tree already in decline, with crown dieback, decay or a poor root system, is one where the extra load and the shading of remaining foliage genuinely matter. The tree's condition decides the answer.
4. Consider whether the ivy is hiding inspection points.This is the most under-appreciated problem. A dense skirt of ivy over the base and lower trunk conceals fungal brackets, cavities, cracks and soil movement — exactly the signs you need to see. Clearing a band from the base upwards restores the ability to inspect.
5. Cut a band through the stems at the base if you decide to remove it.Sever every ivy stem at about knee height and again near the ground, and take a section of stem out so it cannot rejoin. Cut carefully with a saw or loppers without gouging the bark. The ivy above will die over the following months.
6. Leave the dead ivy to fall rather than pulling it.Ripping live or dead ivy off a trunk tears bark and takes patches of it with it, which does far more harm than the ivy did. Let it die back and decay in place; it drops over a year or two.
7. Dig out the ivy roots if you want it gone for good.Cut stems will resprout from the base. Dig out or repeatedly cut back the ground-level growth, or the whole job repeats in three years.
8. Check for nesting birds and roosting bats before cutting.Ivy is heavily used by nesting birds and dense ivy on a tree is a recognised bat roosting feature. Both are protected. Check thoroughly, avoid the nesting season, and take advice if the tree has other roost features such as cavities or loose bark.
9. Leave it if you reasonably can.On a healthy tree away from buildings, ivy is a net gain. It is one of the last nectar sources of the year for bees and hoverflies, it fruits in late winter when birds are short of food, and it shelters a great deal of wildlife. Removing it from every tree as a matter of routine is not good practice.

Tips

• Ivy on a wall is a different question from ivy on a tree. On sound masonry it does little harm and provides insulation and habitat; on poor pointing or render it exploits existing weakness.
• If you cut ivy, do it in winter when there is less chance of disturbing nesting birds, but check for bats and hibernating wildlife anyway.
• A tree that dies with ivy on it usually died of something else. The ivy then becomes very obvious and gets blamed.

Common mistakes

• Pulling ivy off the trunk — The holdfasts grip firmly and tear bark away with them. Cutting at the base and waiting is slower and does no damage.
• Removing ivy from every tree as routine maintenance — It destroys a great deal of habitat for no benefit on a healthy tree, and takes away one of the few late nectar sources in a British garden.
• Cutting ivy in spring without checking — It is one of the densest and most-used nesting habitats in a garden, and nests in use are protected.
• Ignoring ivy on a tree you are worried about — It hides exactly the signs — brackets, cavities, cracks, soil heave — that you need to see at the base.

If it doesn't work

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