Just over two years ago, when I first moved into my house, the garden was overrun. You couldn’t see one side of the house for brambles and ivy, and it was a job making it to the front door without getting a ladder in your tights.
One plant in particular was causing myself, and my family, lots of worry. The culprit was the Common ivy (Hedera helix), which ran fervently around the house and along the garden walls. It covered the borders and wrapped around trees.
So, like explorers in the jungle, we cut our way through, received death by a thousand cuts and started to tackle the ivy-laden overgrowth. After all, that was the right thing to do, right?
Perhaps yes, perhaps no.
The benefits of ivy
The main case against ivy is that it is seen as a Day of the Triffids-esque parasite; a plant which leeches the life from trees, plants and buildings.
However, ivy does not penetrate a tree’s bark or roots – the short, root-like growths visible on climbing stems are for support only. And, according to the RHS, “[the ivy’s] own root system below ground supplies it with water and nutrients and is unlikely to be strongly competitive with the trees on which it is growing.”
Ivy as an insulator
An study from Building and Environment in 2012 found that Common ivy increased the mean external temperature of a North-facing wall in winter by 0.5°C and reduced temperature fluctuations by over 3°C. This resulted in a reduction in energy losses of around 8%.
Ivy as a pollinator
I was inspired to write this post two weeks ago after coming across the most amazing ivy bush (Atlantic/Irish ivy -Hedera helix subsp. hibernica) which was teaming with insects and birds. I saw bumblebees, honey bees, hoverflies, wasps, ladybirds and other insects humming around the plant, all very much in their element.
In terms of bees, a study from the University of Sussex found that on average 89% of pollen pellets brought by worker bees to hives were from ivy. And 80% of honey bees foraging on ivy were collecting nectar. Having access to this supply of nectar and pollen late in the year improves the chances of successful over-wintering for the bees.
Ivy as a habitat
In my own garden, I have seen a charm of goldfinches and a host of sparrows hide out amongst the ivy, as it provides shelter and camouflage. Ivy can also provide berries and a suitable place for nesting. I feel that having varied and suitable habitats in the garden can often benefit birds more than putting out bird food, and can be more cost-effective.
Ivy is also an important source of food for some butterfly and moth larvae such as holly blue, small dusty wave, angle shades and swallow-tailed moth.
Ivy as a source of colour in the winter
Ivy is evergreen and due to the varieties available, it can come in many different shades and textures. This makes it an attractive option to add colour to your garden in winter months.
The real benefit is clear in terms of wildlife and habitat, as it is becoming increasingly clear that a more diverse and wildlife-rich garden is key for keeping pests and diseases to a minimum.
When to remove ivy
Everything in moderation, as they say. Despite the benefits listed above, there is still need to remove ivy, or any plant, in the garden if it becomes a threat.
If the ivy is causing structural damage
Boston ivy (Parthenocissus tricuspidata) is not likely to cause any structural damage to walls, but Common ivy can, as it supports itself by aerial roots which can penetrate cracks in the stone.
It has been recommended that ivy is not grown on the following materials:
- weakened brick
- old brick
- wooden walls and fences
- painted surfaces.
It is worth noting that ivy on your house is unlikely to cause damp (the thought being that dampness is increased due to slower drying conditions following rain) and may, in fact, have a slight drying effect on mortar and will also provide some degree of insulation in winter, particularly evergreen ivies covering exposed north and east-facing walls.
If the ivy is smothering the crown of a tree
If ivy reaches the top (the ‘crown’) of the tree, it will flourish and create a type of sail and can catch the wind. In strong winds, the tree is at risk from toppling over. In this instance, it would be advisable to take preventative measures and remove the ivy, especially if the tree is old, weak or damaged.
If the ivy grows over a neighbour’s property
This applies to any plant, shrub or tree in your garden. You are responsible for where the plant grows. It is polite to keep plants in check, and if they do get out of hand, notify the neighbour first before removing ivy that has travelled over onto their property.
If you or someone you know is allergic to ivy
Traditionally, English ivy isn’t poisonous, unlike its American cousin Poison ivy, but that doesn’t stop people being allergic to it. If someone who uses the garden frequently and is allergic, it’s probably best to get it removed.
Check out the RHS guide on how to safely remove ivy.
With all this in mind, only remove ivy if you truly have to. They say the most wildlife-friendly gardens are those of which are allowed to run amok, the ones where nature takes over and an ecosystem can be sustained. The nectar, pollen and berries that ivy provides are an essential food source for insects and birds during autumn and winter when food is scarce.
At the end of the day, ivy can be the least of the problems your garden. In my opinion, dealing with things like badgers, or – god forbid – Japanese knotweed are far more pressing, as both can carry serious financial and emotional ramifications.
Ivy’s not that bad: it’s not killing your tree, remove it only if you have to.
Further information about ivy: