I have a dream: Stop fantasising about what to do with the garden as spring hoves into view

It's hard not to get carried away fantasising about what to do with the garden while you're huddled indoors. But for once, says Emma Townshend, I might have had a vision I can actually pull off.

Never mind the bulbs and blossom – for my money, early spring is the optimum moment for crazy outbreaks of unrealistic garden fantasy. "This year I will grow all my own vegetables for Christmas dinner." "This is just the right moment to build a golden pergola festooned with roses named after my entire family." And my personal favourite: "Ooh, think I might install an outdoor shower-slash-cocktail-bar." The horticultural equivalents of deciding to make a Battenberg cake: great in theory; in practice, bonkers.

Not all spring fantasies are this grandiose, of course. Even more modest manifestations such as wanting some really good garden furniture can spread like a contagion through the whole population, brought on simply by those rare quasi-spring moments when the British sun pokes out its head and threatens to raise the temperature from freezing to just mildly cold.

It doesn't help that, like Glenn Close in Fatal Attraction, winter has a nasty habit of resurfacing just when we thought it was gone for good. Yep, there we were feeling all relieved that the nightmare was over, and then the Wicked Witch of the Snowy North bobs back up with icy bubbles streaming out of her nose. In the face of which we retreat to the sofa with our daydreams for another week's unrealistic, yet extraordinarily detailed planning.

This year I find myself pondering sweet peas. New and seductive varieties for 2013 include "Old-Fashioned Scented" from Suttons, a selection of smaller, more fragrant blooms that remind me of 1970s village show prize-winners (£1.85 a packet, suttons.co.uk). Thompson & Morgan, meanwhile, has a tropical "Blue Shift" (£2.49 a packet, thompson-morgan.com) , which changes from mauve to Caribbean azure during its flowering. And most tempting of all, there's "Almost Black" from Sarah Raven, a delectable shade of deep, dark purple (£1.95, sarahraven.com). Whichever way it goes, in my dreams the sweet peas are very promising this year.

And frankly I can always be suckered by a temptingly optimistic spring offer. I'm pretty partial to the one Suttons is doing on strawberries: £50 worth of plants, plastic mulch and a grow tunnel for only £19.99. Ahhh, my own fruit by June, wandering out into the garden, picking a few and putting them into a glass of Pimm's…

Sorry, I wandered off a bit there. Anyway, I should know now about the fantasy bit, because I've just had a session of effective horticultural psychotherapy. Slightly desperate about my own garden, this January I called for Ann-Marie Powell, Chelsea-gold-medal-winning garden designer, whose work on small plots I'd got to know better while writing a piece for this very magazine about her recent book.

She turned up looking both extremely cheerful and very glamorous. "Ignore this," she said, "I don't usually turn up dressed like this, I'm going on to a party." We soon got down to basics. "I'm starting to hate my back garden," I practically wept. "I can't get it under control and I'm not sure any of it is actually usable. For normal things like, um, sitting."

Talking through your garden with a good designer is a totally fascinating process. What bits of the garden do I want to emphasise? What do I want to keep, and where am I aiming to get to? I showed her Los Angeles gardens I've had lifelong crushes on: Richard Neutra glass-and-concrete creations, Huntington's crazy desert cactus accumulations, and the wilder whimsy of celebrated set designer Tony Duquette, who made several gardens in the mountains using wooden orientalist treasures saved from the productions of massive movies such as Ben Hur.

"But are you sure this is really what you want?" asked Ann-Marie, clearly accustomed to this kind of bonkers, as she interrupted me in mid-sentence ramble about that bar-slash-outdoor shower. "This doesn't sound that much like you. Is this your fantasy of all the things you wish you were, but really actually aren't?"

This stopped me in my tracks. For several days I pondered her wisdom. Fantasy plays more of a role in my garden than I had hitherto realised, but a few more days conversation with like-minded fools made me realise how much company I have in my affliction. I still want the outdoor shower. Just maybe not this year. And hopefully I've got just enough realistic energy to grow those deep, dark, almost black sweet peas.