24Aug 2010 - She remains best known for playing the youthful wizard Hermione Granger in the Harry Potter films. But now Emma Watson is weaning teenage shoppers away from mass-produced chainstore clothes in favour of ethical fashions made on a small scale in some of the world's poorest nations.Watson's latest collection for People Tree, which works using strict Fairtrade and environmental guidelines, will be launched at "a garden party to make a difference", a 12-day environmental festival organised by the Prince of Wales that will be held next month in the gardens of his London home, Clarence House.

Fashion experts say Watson, now 20, has a considerable amount of influence among girls and young women who have watched her gradually shed the image of the somewhat frumpy Hermione to emerge as a fully fledged fashion icon. "I think a lot of young women have grown up with her, seen her develop her style," said Emily Sheffield, deputy editor of British Vogue. "She is a classic English rose."

Traditionally, ethical fashion is a sector associated with older consumers more concerned with provenance than design. But Orsola de Castro, co-curator of Esthetica, the British Fashion Council's eco-sustainable initiative, believes this perception is changing and Watson is part of that. "We have to make ethical fashion available and interesting and glamorous for the public," she said. "Celebrity support is providing that platform."

Watson says she wants to create clothes for people of her own age, introducing younger lengths and fitted shapes to the People Tree brand. "Emma appeals to younger people and the collection has sold incredibly well on [online fashion outlet] Asos," said Safia Minney, founder of People Tree. "When clothes are worn by someone as lovely as Emma, it brings a whole new customer in."

Watson's previous collection, for autumn/winter 2010, will be for sale from Wednesday from People Tree. "Although I wasn't centrally involved in the design, I had a great fun in helping People Tree select some gorgeous Fairtrade textiles," she said. "There are even a few party dresses, such as the little black satin tulip dress which can be dressed up or down to suit any occasion."

The paradox is that while People Tree is relatively affordable – items cost as little as £20 – Watson is a highly visible fan of upmarket fashion and haute couture.