Why the ivy can be bad news for some trees

Nature: Yes, ivy can look very decorative. But it has its dark side too, says Rex Hancy.

Every time I leave by way of the kitchen door I am reminded I must trim back the ivy which threatens to overwhelm the garage wall. Years ago I planted a decorative form for its potential ornamental effect. After a long wait, success was achieved and we have a fan of variegated green to take the eye off monotonous concrete blocks. That is all very well but the price is high. Twice a year I am forced to trim back the luxurious growth. The last cut was in September. Since then the top growths have put on another foot and could work their way into the roof structure.

A well-rooted plant and another mild winter has meant ivy has suffered no check. The result may be seen all around us. Ivy has a place in the great scheme of things. Most people are able to recite a list of benefits conferred by this paragon of plants. Actually, ivy has benefited itself by a highly-successful PR campaign. Anyone uttering a word against it is in danger of being roundly condemned, as indeed have I.

In fact, I agree with the list of virtues but continue to state that it is possible to have too much of any good thing. After the recent big blow, I was not at all surprised to see gaps in roadside verge hedgerows where young trees and shrubs had been toppled because too much of the creeper had led to what is known as the sail effect. This, I have been told in the past, is impossible because ivy grows prolifically on only aging or weak specimens of trees and shrubs. My one and only example of a blackthorn bush was almost destroyed before I became fully aware of the situation. Naturally remedial action was taken and last year we saw flowers there again. This spring I have had to cut back the clinging tendrils which threatened to engulf our magnificent spindle tree. Enough ivy has been left lower down to provide the much-publicised benefits. In a fairly short space of time the job will have to be repeated. Ivy can be decorative and beneficial but it can also be hard work.