Monday, 9 August 2010
Keep Warm with Ivy
If it doesn't destroy your house, ivy may save it. It can protect your home from pollution or salt, and it can provide the ultimate 'living' insulation.
A study commissioned by English Heritage, and reported in the lastest issue of the Royal Horticultural Society's magazine The Garden, has found it can warm walls by an aversage of 15 percent in winter and cool them by 36 percent in summer.
Of course in Australia ivy (Hedera helix) does other things, like escape into the bush where it strangles native trees and suffocates other plant life. It's a much hated weed in many parts of the country. But...if you can contain it to your home and keep it free of berries, it might just be a good thing. Maybe....
Like lichens, mosses and algae on your roof, it may not always be a bad thing. If you like the look of it and you can control it's spread into places where you (or the bush) doesn't like it, then things that cling to your house can be good.
The study does accept that if a wall is unsound, ivy can get into cracks and holes and make then worse. The same is true of other penetrating creatures like lichens.
But if you have a 'sound' wall, the benefits are likely to outweight any problems. The message is, I think, to not see the world as black and white, right and wrong, and so on. Consider everything on its merits, even that pesky ivy.
The obvious question is what other creepers could you grow to the same effect that might have a lesser impact on the environment. These might be Australian natives, plants local to your area or exotics that don't spread. The creeping fig (Ficus pumila) might be one alternative but you do have to keep it regular pruned - to stop it turning into a large-leaved shrub.
A website on weeds of the Blue Mountains suggests replacing Ivy with: Old Man's Beard (Clematis aristata), Twining Purple Pea (Hardenbergia violacea), Milk Vines (Marsdenia suaveolens,
M. flavescens, M. rostrata), and Native Violet (Viola hederacea), although some of these are ground covers and none will cling to the wall quite like ivy.
There must be others you can think of?
Image: Ivy as insulation and weed, at Malmsbury in central Victoria.