The essential act of pruning

I just bought a pair of Felcos. This actually makes me a fully paid-up grown-up. Felco, if you didn't know, sells the tippity-top class of secateurs. The coolest girls at Kew Gardens wear their Felcos on the belts, which thread through their skinny jeans in a leather holster. It's this holster which is the key to the Felco appeal - along with the distinctive, rather thin red pair of handles, which have some sort of patent Swiss action that allows them to glide back and forth with gruesome ease.

Now I just need something to chop, so who better to consult than the author of a new book called How to Prune? John Cushnie is the owner of the warm, lilting tones on Radio 4's Gardeners' Question Time. Deeply charming but possessed of a dry sense of humour, Cushnie is often to be heard gently taking the rise out of his fellow panellist Bob Flowerdew.

So, does he have a pair of Felcos? "Ah, no. Nor do I have a holster. I absolutely refuse. You see all these people, friends of mine, walking up and down like it was a showdown at the OK Corral. Honestly. I'm from Northern Ireland," he adds, laughing. "With all the troubles we've had, you can't walk around with a holster on."

Cushnie is the perfect person to tackle the question of pruning, his blunt, practical approach matched with a gentle sense of humour about human nature. "We all have gardens, so we all have to garden. If you can walk from your front gate in to your house, you've either done it with a machete or you have gardened.

"But so many times," he adds, as if it was the saddest story in the world, "a man and a woman have bought a selection of plants and there comes a time when she sends him out to knock the thing into shape. If he has any sense, he'll do it the day he's told. But so often, it's totally the wrong moment in the year, and it kills the plant."

This is where Cushnie's expertise comes in. His argument is that everybody needs to cut things back, so everyone should know how to do it properly, and he starts right at the beginning: "Clean, sharp blades."

Though he shows a sad lack of interest in the brand name of his secateurs, the neat job he does of pruning is inspiring: his newly tidied plants give me the same sense of satisfying order that I get from an airing cupboard full of nice ironing.

What a shame he isn't always on hand. Luckily, his book lets everybody have him as a sort of pocket granddad. You can look up the plant you need to prune, then follow the photographic guide with before and after pictures - perfect illustrations to help me with my black bamboo, old enough now to need thinning. I find it easy to work from a picture of what the finished article should look like, directly copying his neat example.

Does this professional interest make it difficult to walk down the street without thinking about pruning? "Oh, well, possibly there is a wee bit of that. People do make some catastrophic mistakes - you'll see them dotted all around the country." I find myself longing to ask him the worst thing he's seen. "On Gardeners' Question Time, you find time and again that someone asks a question, and you are wondering how to say 'You've done this completely wrong' without being terribly rude."

Cushnie's answer was to write his book, which is encyclopaedic without being overwhelming, a gentle romp through the world of pruning, rather than a technical slog. You'll go out in the garden, Felcos or not, knowing what you are meant to be doing, and why. And you can cheer yourself after a brutal session with tempting images of the fruits and flowers you'll have if you prune properly.

"People are afraid to cut things back. But left to their own devices, plants just get to be untidy messes with fewer flowers and fruit. We prune to increase growth. It's a lesson that has to be learnt. People deserve to know more about it."

'How to Prune' by John Cushnie (Kyle Cathie, 19.99) is out now. Felco secateurs are available from www.worldoffelco.co.uk