Erdem Moralioglu has transformed the girlish garden print into a modern fashion statement, beloved by everyone from Keira Knightley to Michelle Obama. He talks to Carola Long

So verdant that you can practically smell the petals, Erdem's prints are the freshest take on the summer dress this season.

The London Fashion Week designer has successfully moved the classic garment away from any lingering associations with Laura Ashley or Hyacinth Bucket, and turned it into something both pretty and modern. More cool cocktail party than the Queen's garden party.

"Accidentally beautiful," is how Erdem Moralioglu describes his aesthetic, and it's this sweet, unaffected prettiness that has won over women who normally 'don't do florals'. That, and the fact that his silhouettes tend to be clean and graphic – all the better to offset the intricacy of his designs. "There's all these flowers and it could be quite saccharine," he says, "but actually there is something quite strong and graphic about them."

However, you don't need to buy designer clothes to feel his influence. All those blurred, digital, or meadow-flower prints on the high street – such a breath of fresh air after the fierce Eighties shapes and colours of the previous season – have been inspired by the impeccably well-mannered and modest 32-year-old with 1940's librarian hair and heavy glasses. What these homages don't have, however – and this is where the designer has cleverly made himself rip-off proof – is Erdem's attention to detail, his combination of imagination, painstaking craftsmanship and quality; he uses lace from Sophie Hallette, which supplies many of the couture houses. And Erdem's dresses aren't just about print; his spring/summer collection included a dress made from overlapping three-dimensional petals in shades of pink, lilac and lime green, and taffeta dresses in cornflower blue and coral appliquéd with delicate pieces of scattered black French lace.

His printing technique involves the designer playing around creatively on his computer for hours, digitally altering prints by blurring them or re-sizing them, painting over them and destroying them. "It's always quite a lengthy, organic process and we never really know what the end result will be," Erdem says. "The previous season had been quite blurred, and this time we wanted something really saturated and hyper-real in a weird kind of way."

The starting point for the collection came from a trip to Kyoto in Japan, where he found Japanese studies of English flowers and illustrations of "modan garus" – a phonetic Japanese translation of "modern girls" – who in the 1920s eschewed kimonos and started wearing Western dress.

"They were financially independent, sexually liberated women, and that started me on this whole kind of trip," he says. "I loved the idea of women taking apart a kimono and putting it back together again, and that was the starting point for some of the dresses."

The prints in the spring/summer collection – which range from intense Chelsea-Flower-Show-on-acid profusions of brightly coloured pansies to monochrome patterns – could give the impression that Erdem is London Fashion Week's answer to Alan Titchmarsh. That's not the case, though: "I'm not hugely into gardening," he says. "In fact our garden looks very much like Chernobyl."

Erdem's studio is in East London, the established stomping/training ground for young British designers. However, like Christopher Kane, based in the same area, Erdem has successfully moved beyond the London Fashion Week stereotype of young, East London scenesters making imaginative but sometimes difficult-to-wear creations. He designs clothes with such finesse and attention to detail that they are desired all over the world. Erdem's 35 stockists include Barneys, Saks Fifth Avenue and Harvey Nichols in Hong Kong.

The sophisticated, universal appeal of Erdem's dresses and skirts – he's not really a trousers kind of designer – is evident from who's worn them and to what occasions. Sarah Brown increased her fashion credibility tenfold when she chose an abstract-print Erdem dress for the Labour Party Conference last autumn; Samantha Cameron wore his designs throughout the election campaign and asked him to design diaries for Smythson last autumn; and Michelle Obama has worn one of his watercolour floral skirts. Away from politics, on the more overtly glamorous red carpet, Claudia Schiffer, Keira Knightley and Romola Garai have all worn his dresses. Although Erdem has said in the past that he was "thrilled" to see Anna Wintour wear one to a gala in New York, today he's more philosophical about the real effect of celebrity endorsement, asking: "Have you ever bought something because someone famous has worn it? No. I think that's true across the board. Women buy things because they have an emotional response to it and they think it will look good."

This sense for modern femininity over trends, and the potential for establishing an enduring label, were among the reasons Erdem won the first British Fashion Council and Vogue Designer Fund in March. Worth £200,000, it's the largest sum ever awarded to a fashion designer in the UK – by a long way – and is intended to help designers create a viable business as well as beautiful clothes. Although it's by far the biggest financial award Erdem has received, it's by no means the only accolade he has under his belt. He won the 2007 Swarovski BFC Fashion Enterprise Award, followed by the BFC's Fashion Forward Award in 2008.

Born to a Turkish father and English mother and raised in Montreal, Erdem moved to London to attend the Royal College of Art, where he received his master's degree in 2003. After graduating he relocated to New York to work in Diane Von Furstenberg's design studio, before returning to London to launch his eponymous label in 2005. He says he always wanted to become a designer; aged six, after his parents took him to see The Nutcracker in Montreal, he came home and designed clothes out of paper for the cast. Were his parents impressed? "I think they were a bit worried," he laughs.

Erdem can't remember wanting to work in any area other than fashion, and the only ambition he can think of right now is to have a shop in either London or Paris. Would he want to show in Paris? "I'm very happy in London," he says. Thanks to his irresistibly romantic vision, London is very happy to have him.