Do you look at this picture and shudder in horror? Or does it fill your heart with happiness that someone has created such a wildlife-friendly vertical habitat? Well, I think for me it’s a mixture of both. But in New Scientist last week, writer Clare Wilson suggests that an ivy-covered wall can have lots of benefits that I for one hadn’t considered.
I have always admired the splendid ‘plant walls’ that are being created, both indoors and out, but they seem to be very difficult to maintain – the requirements for watering, feeding and protection from exposure seem daunting. When it’s done well, it can be spectacular.
However, most of us don’t have the money, time or know-how to create something like this. Wilson suggests that the Hedera species are a quick way of covering an ugly outbuilding or fence, and notes that birds like the berries, and many pollinators relish the flowers, including the recently-arrived ivy bee.
However, there are other benefits to an ivy-covered wall. For one thing, it can help to insulate your building. In a study by Tijana Blanusa at the University of Reading, it was found that ivy helped to slightly warm a room in winter. It also cools a room in summer both through creating shade and through the water evaporation from its leaves. It is better than either Boston ivy (Parthenocissus tricuspidata) or climbing hydrangea (Pileostegia virburnoides) at reducing the temperature in summer, probably because the leaf cover of ivy is so dense.
But, I hear you say, doesn’t it also destroy my walls? The RHS say that ivy doesn’t normally damage walls unless the masonry is already cracked – the aerial roots of ivy can’t penetrate sound mortar. Having said this, though, Wilson admits that once ivy gets going it can take over very quickly – in fact, she recommends only growing it where you’re happy to get on a ladder and prune back any eager shoots that are reaching for gutters or roof tile. Apparently anti-graffiti paint also works: it contains an ingredient called silane which reduces the attachment of the roots.
Wilson also suggests containing the plant by popping it into a pot, or putting it in a small patch with a few bricks – the words ‘good luck with that’ spring to mind, as in my experience you only have to go on holiday for a fortnight to come back and find that your garden has been transformed into an ivy-covered version of the Sleeping Beauty’s bower. Still, this is an extremely useful wildlife plant in the right place, and one of the very last sources of pollen and nectar for autumn insects.
I should probably put in a word here too about ivy in forests. I know people who loathe the way that the plant seems to smother trees, although it is only using the branches and trunk as a support. According to the BBC, ivy will not normally harm a healthy tree, which is big and strong enough to continue to photosynthesise in spite of its ‘hanger-on’. However, trees which are already weakened through disease or age can be brought down by the sheer weight of ivy, especially in high winds. I can think of a couple of trees at the edge of Coldfall Wood which are gradually being brought down by the volume of ivy.
On balance though, my personal belief is that ivy can be a good friend if you keep an eye on it in the garden, and tolerate it in other places. As we go into winter, it provides places for all kinds of animals to roost and hibernate, and it can brighten up all kinds of miserable concrete structures that would otherwise be an ecological desert. But what do you think? Let me know whether you’ve had to wrestle this plant to the ground, or if you have fallen in love with it. I’d love to know.