Space invader: She thought it would add charm to the front of her house; now Emma Townshend is locked in a desperate battle to tame her rampant, triffid-like Wisteria

I recently read about a study that alleged wisteria is one of the most unpopular plants with house buyers. "How can that possibly be?" I thought, "Lovely old wisteria, how unfair." All my life I've longed for a wisteria-covered house. I love how it looks in winter; its grey winding stems, its neatly pruned buds. And then I love the dozens of spring blooms, the amazing perfume, and the way the leaves sit in layers around the house, making it look protected, and tingeing all the interior light with green.

This was, of course, before I had a wisteria. Well, it was when I had a little wisteria. I notice that most people with a wisteria seem to have chosen some reasonable sized one that grows about halfway up the house and then neatly stops. Somehow, when I went round the garden centre, I had to choose a cultivar of titanic proportions. Even though it's competing with a whole front garden full of plant friends, it grows like a triffid.

Worse still, in this summer's heavy rain my roof started to leak. An investigation in my attic revealed a) the biggest wasp nest I've ever seen; but more vitally, b) the wisteria's pointy brown old witchy fingers have crept under the tiles, dislodged the liner, and are responsible for the brown patches on my bedroom ceiling.

Firstly I thought I should deal with the wasps, but happily, they had already vacated the premises. Maybe they got the fear that it was only a matter of time before the wisteria came for them too.

But what am I supposed to do about the wisteria, a plant so territorially aggrandising that it will grow into a completely darkened roof space, rather than stay outside where photosynthesis is actually possible?

I had to buy a new ladder just to reach the wisteria, which is now growing along the telephone lines. In the 1780s, a Dr Bertholon discovered that plants are actually attracted to electrical currents, it gives them some sort of buzz. Well, they are ruining mine.

So instead of giving the wisteria the orderly July pruning (the length of an arm in July/August, the length of a hand in February), I ended up hacking off whole sections of plant. Believe me, it doesn't even look upset. This plant has the hauteur of a Roman emperor in full toga get-up. It stared down at me from the front of the house with the cold compassionless gaze of a five-year old looking down at an ant.

I mounted the ladder with trepidation. For a start, it's five metres long, which is considerably higher up the outside of a house than I usually want to be. It feels a bit too much like the start of a Casualty episode. Then I got into a row with one of London's top graphic designers, who was holding the bottom of the ladder for me: "You're being dangerous! I'm walking away!" he growls, taking one hand off the ladder in a threatening gesture of non-cooperation. I have to come back down and actually beg. "Please stay! Please hold the ladder!" Which he eventually does, despite his low opinion of my safety protocols.

The interesting thing is that once you resign yourself to hacking at a wisteria, you are on the road to somewhere better. These domestic tyrants will flower best when grown according to the sort of scheme you see on French houses in spring: one main stem, with clear outreaching branches going equally in both directions, pruned back almost to the wood, to create a profusion of blooms close together.

In what should be every plant lover's bible, The Well-Tempered Garden, by Christopher Lloyd, he argues that without a firm pruning in the middle of wisteria's growing season, you may wait years for the flowers. Which are surely the main point of growing the thing. So if you haven't done it already this summer, shorten all the current season's growth to a couple of feet, and take a saw to any branches that are going the wrong way. This way there is still some sunshine left (in theory) to fatten up next year's buds.

And, if you don't get it right the first time, you'll have at least cleared enough to see where you need to get to next. As long as you can find someone to hold the ladder. n