Sister act: Rodarte is New York's hottest label

Fans include Anna Wintour and Natalie Portman – yet high art, not the red carpet, inspires their collections. Alex Fury meets Kate and Laura Mulleavy, creators of New York's hottest fashion label, Rodarte

You can't help but wonder what Kate and Laura Mulleavy – the siblings behind the New York label Rodarte – were like in high school. In-crowd or outsiders? Fêted or shunned? The one thing they could never have been is average.

The same is true of their Rodarte catwalk shows, a polarising force in the midst of New York fashion week, where they've shown since 2005. Buyers either see their work as exquisite sartorial investments, or shock-frocks destined to clutter sales racks. Reviews oscillate from hyperbole to hostility, some press applauding Rodarte as a blast of fresh creative fire, others condemning them as a case of the Emperor's New Clothes. Their latest collection, shown in June as part of Pitti Immagine in Florence, was a prime example: a clutch of jewel-coloured silk dresses and hammered-gold jewellery presented in a blasted-out, mid-century shopfront. For every reviewer who rhapsodised about beauty amid brutality, there was another who saw nothing more than Technicolor kitsch dressed up with art-school pretensions. High art, or high camp?

Speaking with the Rodarte sisters, however, puts your mind to rest. Maybe the lines are drawn between those who have and haven't met the sisters themselves. 'Art-school Goth' is a label attached not only to the clothes (all inside-out seaming and clever ways with handicraft embroidery) but the designers, too. Both sisters fall into the pale and interesting camp – they look so alike they're often mistaken for twins. In person, they're less intense than their clothes initially suggest. What puzzles me most is how two girls can stay quite so pale under the sun of Pasadena, California. Perhaps that's just stereotyping – the California of Rodarte isn't bleached-blonde, bikini-ed or perma-tanned. "We see a different side of California," says Kate Mulleavy, aged 32. She's the one with poker-straight hair; Laura, aged 30, looks a little like Winona Ryder in Heathers.

That movie reference feels entirely appropriate for the pair, not only because they both dress, and count among their friends, the kind of Hollywood A-listers that other fashion designers would open veins for – Kirsten Dunst, Reese Witherspoon and Natalie Portman, whose costumes they helped created for Black Swan – but because cinema is part of their cultural language. A few years ago, I asked the Mulleavys how they would describe modern fashion. They said "cinematic" – something they still feel today. "For me, fashion is a way of telling stories that are visual, in the same way as cinema," states Laura, before Kate throws in: "Film has become a modern way to communicate. If I tell someone I come from where they filmed The Lost Boys, they get it". That's probably a way into the Rodarte world, too, where their California girls wear gladiator skirts, melting-wax shoes and Ming vase-print organza dresses. "We love beauty in a strange way," is the Mulleavys' simple explanation.

California is key to understanding the Rodarte story. The Mulleavys still live in Pasadena with their parents, the Rodarte studio a short downtown drive away. That wasn't always the case: the first Rodarte collection in 2004 was put together in the family living room, assembled on domestic machines and funded with a meagre $20,000 start-up capital, garnered by Laura slogging her guts out waitressing and Kate flogging a prized, vintage record collection. It won them a place on the New York fashion week schedule and an audience with Anna Wintour. That's the kind of fly-by-the-seat-of-your-pants fairytale beloved by both fashion and Hollywood.

Their collections, oddly enough, all have a link with their hometown – they've recently published a high-brow, high-art monograph in collaboration with photographers Catherine Opie and Alec Soth that seems to explore the synergy between the Sunshine State and Rodarte's decidedly dark designs. "You explore the things that you know," said Kate, Laura interrupting with, "We lived in Alabama for two years – and that does creep in every now again!".

The Mulleavys' distance from New York – where they show their collections – is not only literal but also ideological. New York fashion is lean and mean, streamlined. It's Calvin Clean, Oscar Pay-My-Rent-a. Rodarte collections aren't about reinventing notions of evening dressing or the 'transpersonal' trouser. They are inspired by bordertown sleep-walkers, by Japanese horror films, by myths of women exploding in fire and rising phoenix-like from the ashes. They show collections patterned with Seventies woodgrain. They hand-knit mohair on broomstick handles. If they gold-leaf their models' chignons, it's not about a 'total look' or 'modern luxury' – it's about making the girls look like C-3PO from Star Wars. It's no wonder the American press who saw their early collections pronounced the label's name 'Rod-art'. Art was the only term they could think of for it.

Raise that idea with the sisters and you get a mixed response. "You can't deny the way that you work. I think that our tendencies are more artistic than anything," says Laura. "If you're an artist and you make a dress, the idea behind it makes it art. It's not necessarily just the medium." That was Kate; she studied Art History at UC Berkeley, hence the analytical slant. Laura's focus was literature and the Modern novel: "I like telling stories," is Laura's response to questions about why she designs.

This lack of a traditional fashion education is part of what makes their approach to design so interesting. "We were never taught how to put a collection together. We didn't even know seasons, really. We didn't know we had to do coats for winter!" says Kate. That sense of art-school impracticality has informed Rodarte's designs from day one – sometimes to dazzling effect, sometimes hampering the translation of those concepts onto the body of a woman. "I don't really know what wearable means, honestly," says Kate. "When we discuss our ideas about a collection – if we didn't tell someone it was a fashion collection, they could think we were telling a story or making a movie or something. There's an interesting dialogue."

Rodarte may shy away from calling what they do art, but they're not afraid of an art-school reference. The Pitti Immagine collection drew on Fra Angelico and Bernini, which are pretty hefty, Renaissance guns to pull out for a dozen evening dresses. But as with so many of their catwalk shows, there was something magical about the experience – fresco-bright colours glittering with embroidery against crumbling plaster walls, the dresses looked like Blessed Virgins ensconced in provincial hillside shrines.

There's a dose of the High Renaissance of Italian fashion to these clothes, too. It's easy to imagine them doing quick business at the Oscar roster – Natalie Portman famously eschewed Christian Dior for Rodarte at this year's Academy Awards. But the Pitti Immagine dresses are destined for the permanent collection of the Los Angeles County Museum of Art – "It ended up going to LACMA and not Neiman Marcus [the department store]. That's great – I think you can do both," says Laura.

You certainly can, but in a time when designers are under increasing pressure to churn out ever-faster fashion – witness the proliferation of commercially-motivated, trend-focused 'resort' collections, barely-masticated before being spat out into the consumers' wardrobes en masse lest a label be seen to be missing a trick – the Mulleavys' painstakingly-wrought one-off pieces seem to buck the general trend. It's tempting to think of it as an 'anti-resort' collection, but the Mulleavys have a handle on the realities of the fashion business. "I feel you have to be aware of commercial restraints. You can't run your own business and succeed if you're not dealing with the business aspect," Laura says.

The Rodarte label approaches couture not only in quality, but in price: a handful of exclusive stores across the world stock a handful of exclusive pieces, such as hand-knitted cobweb sweaters, artfully tattered chiffon dresses and hand-painted and embroidered Ming-vase dresses, all retailing in high four-figures. However, in 2009 the label linked up with the American chain store Target for a mass-market line, and it now designs a more 'accessible' (read: cheaper) capsule collection for the New York boutique, Opening Ceremony.

How much of a concern, then, is wearability for these designers lauded as New York's answer to haute couture? "There's things stores need, there's things clients want to see, and there's things you want to make," say Laura carefully.

"In the best scenario they're all overlapping." "I think you're there to challenge people," counters Kate. "I don't care how wearable it is, it could be the most wearable thing in the world, but people will be more interested if it just challenges them a little bit."

Sometimes, it's a little dizzying being tag-teamed by the Rodartes: they finish each other's sentences, elaborate on statements, talk over one another – but in the best possible way. Rather than guarded, press-ganged conversation, it's an impassioned dialogue at breakneck speed.

Seven years and several awards after their first homemade collection hit the coveted front page of Women's Wear Daily and catapulted them to instant fashion fame, the Rodarte sisters have an undiminished passion for what they create. "The truth about clothes is that they transform you. There's no boundaries in terms of what's interesting," says Kate. Laura, of course, interjects: "It's about making you look amazing. That's why people buy our clothes."