Finding the plot: Anna Pavord meets a first-time gardener who fell in love with the growing game

"Well that's a first," I thought as I turned up earlier this year at Laetitia Maklouf's flat in west London and found, pinned to the door, a note saying "Gone into labour". What with the new baby (her first) and other things, months passed before I caught up with Maklouf and her balcony, which is what I wanted to talk to her about.

She lives in a first-floor flat, converted in the Eighties to make one big living space. Glass fills the south-facing side with massive sliding doors leading to the balcony (about 5m long and 2m wide) added during the conversion. When the glass door slides back, the balcony, filled with plants, becomes part of the living space, a green jungle of ferns and summer jasmine, hanging baskets and tubs, cyclamen in pots with arums towering over them. Beyond is a dense urban skyscape of roofs and chimneys, but veiled by the growing stuff that fills so much of the view.

The flat, she said, had previously belonged to the model Kate Moss, who had abandoned it before it was finished. The balcony was mostly filled with stuff destined for a super-modern kitchen (long lengths of stainless-steel worktop) which never happened, but which was all left behind when Maklouf moved in. For five years, the balcony remained a junk yard. Maklouf was a party animal, the flat a base but not a home.

So what changed, I wondered. What hooked her into growing things? A Christmas stocking, Maklouf says, found at the back of a cupboard in her flat. She was in her late twenties, at a lowish point in her life, temping in various unsatisfactory jobs, when she came across the stocking which still had in it a walnut, a dried-up tangerine, a £1 coin. And a packet of sweet-pea seed.

"I'll plant them, I thought. Then they'll die. And that'll prove how ghastly my life is. So I got a mug from the kitchen, went downstairs and filled it with earth from the bit of garden there – probably cat poo I thought, not earth at all. I pushed some of the seeds in. And they grew. It was a complete miracle. They didn't survive to flowering size, of course, because I had nowhere then to grow them on. But the fact that they came up at all was a complete revelation to me. My God! I thought. How on earth did that happen?

"It was like a springboard, a catalyst. I suddenly had this burning desire to understand how all that sort of stuff worked." So Maklouf got in a couple of flatmates to provide her with an income while she enrolled at the English Gardening School, based at the Chelsea Physic Garden in London. "I did everything I could – practical horticulture, plants and plantsmanship, garden design. I suppose I had some idea, like everyone else there, of setting myself up as a garden designer."

That never happened, but she cleared out the junkyard on the balcony and started filling it with plants. She grew sweet peas again, but provided them with two deep wicker baskets instead of the mug, with tall wicker canes to cover with their flowers. She fell in love with auriculas, and was surprised to find they survived rather well, arranged in pots on a small round table on the balcony. She acquired a triangular plant stand to jam into a corner and started to collect scented-leaved pelargoniums. She caught the grow-your-own bug and planted herbs, garlic, lettuce and baby carrots in windowboxes.

She made a moss garden on an old iron tray – her grandmother's – and kept it at the end of her dining table, spraying it to keep it cool and damp. She added ferns, arranged pebbles and shells among them. And again, was amazed to find that the moss and ferns prospered. "I'm not obsessive about it. I'm just trying to catch a bit of the essence of gardening. I love having things growing around me. I like things to look pretty, but I don't struggle. It's supposed to be fun, after all."

Maklouf, who is now 35, likes success, ease and not too much work (or dirty fingernails) in her gardening. She likes the ceropegia (called hearts-on-a-string) that, with very little help from her, dangles down from a ledge beside the fireplace, its heart-shaped leaves smudged with silver like a cyclamen. She likes the Mexican daisy (Erigeron karvinskianus) that flowers all summer long in her pots, the flowers drifting from white to deep pink as they age. She likes the big Nicotiana mutabilis pushed into a corner of the balcony, a four-foot airy stem covered in blooms.

The balcony waves at you as soon as you turn into the neighbourhood, because there's less gardening going on in this area than I would have imagined: one or two brave magnolias (loaded with fabulous red fruit), a wild elder bushing out from a corner, yellow corydalis helping itself to basement steps, but little attempt to plant front gardens, few windowboxes even. So the balcony is an exuberant oasis, limited only by its size and the fact that the floor of the balcony above makes a ceiling that is rather too low over Maklouf 's own space.

But she's continued to be surprised and delighted to find that things mostly grow. A pot of chillies balances next to a pot of lemon verbena. Euphorbia mellifera with sea-green leaves rubs noses with a crinum. There's clipped box and campanula, violets, strawberries in hanging baskets.

Out of this delight has come a book, The Virgin Gardener (Bloomsbury, £20), a kind of recipe book for first-time gardeners full of projects that she hopes will "replace a fear of failure with a sense of fun". It's as much about decorating as growing, about ways of putting things together in unusual ways. The book, she explains, covers "the things I wanted to know when I began, set out in a way I would have understood."

Between them, book and baby (Jemima Velvet, well-trained enough to give Maklouf some gardening time between 12 and 2pm) have put a different perspective on the balcony. More space is now needed, both for prams and plants. So the hunt is on for a patch of real earth, with a bit of living space attached. Until then, Maklouf "lies in the bath dreaming about it".