As Spring slowly but surely approaches, the mind of the gardener will inevitably begin to drift towards all the jobs that need doing to spruce up the garden in preparation for the growing season. Perhaps you might well consider removing the ivy that is creeping up a wall or tree or along the bottom of a hedge as you fear it may cause damage or swamp the flowers. But before you get the loppers out of the shed I implore you to reconsider – and think of the wildlife that lives in your garden; for Ivy is quite possibly one of the most important plants you have for a vast array of species.
Too many times have I passed a large tree either in the countryside or in town that has a mature, but very dead ivy plant crawling up it – that is severed at the base. This is presumably done out of kindness for the tree, because of the fear the ivy will ‘smother’ it or compete with it for sunlight; as though it were an Amazonian strangler fig – which kills its host tree and replaces them like a vampire. But Hedera helix (also known, quite aptly, as ‘bindwood’ or ‘lovestone’) is better likened to a vertical meadow, because like a field full of flowers and grass, it provides both food and shelter to many animals – both large and small.
The Ivy plant is evergreen, so for humans it is aesthetically pleasing as in winter it adds much missed green foliage to trees and walls throughout the country, which is why we often collect it along with Holly at Christmas to decorate our houses. Structurally the Ivy is very useful, because its many branches and twisting, forked trunk provide a dense cover for birds to roost in and both mammals and invertebrates to spend the winter in – safe from the worst of the weather and much warmer than on an exposed branch. The plants thick and supportive network of hairy twigs are also excellent for building a nest in; which is why Robins and Thrushes in particular regularly breed in the well-hidden interior. The leaves are also a food-plant for many invertebrates – whether they be caterpillars or larvae or adult insects, perhaps most well known is the small Holly Blue butterfly, whose second brood of caterpillars feed not on Holly but on Ivy – surely the sight of these sapphire blue insects is worth putting the loppers away?
Ivy produces its flowers in late summer, and although they are not much to look at, you should keep an eye on them because they are a major attraction for many insects, including; butterflies, hover-flies, beetles, true flies, moths, wasps and bees. The flowers are sticky with nectar and bulging with pollen, I recall watching an Ivy bush on a warm September day and seeing four or five Red Admirals quarreling over the flowers amongst bright orange hover-flies all gulping to their hearts content (in order to get their body reserves stocked up for a long winter in someones attic). If you consider how common Ivy is around the country and also that it is usually the only significant source of nectar at that time of year you can appreciate how important it is for our insect populations (and the other animals that eat them!).
The end result of all those smelly flowers however is just as important – in late autumn and even into winter the Ivy swells its ovaries to reveal hundreds of wine-gum black berries. This late crop of food is very welcome for our resident and wintering birds – notably the thrushes – seeing as insects are getting thin on the ground (and in the air) and other nut or fruit bearing shrubs have long been scoffed by squirrels and hordes of Redwings.
If we consider the claims that Ivy kills mature trees and should be cut, it is clear that often this is a case of misunderstanding; many people believe Ivy actually parasitises trees (it doesn’t) or weighs down their boughs (again, not really, unless the branches are already dead and weak), or even that it takes all the sunlight (Ivy rarely grows bushy enough to swamp a tree to that extent and Ivy does not want to kill the tree that is supporting it). Regarding walls, Ivy will only damage the brick work if you try to remove it – which is very difficult due to those suckers on the stem, so the simple answer is – don’t remove it!
(P.S. The main painting attached to this post is by Van Gogh)