Watercress sales are growing faster than the wider leafy salads market, enjoying a 14.5% rise in demand in the multiples last year, according to producers.

"The total market for leafy salads was up only 1.4%, so watercress had a good year in terms of performance," said Simon Conway, commercial manager for Vitacress Salads. A scientific study highlighting the crop's anti-cancer properties provided a sales boost of between 50% and 60% last February, he said, while a mild April provided an early start to the season.

Watercress can be gathered as early as late February and is harvested as late as Christmas.

National Watercress Week, from 11-17 May, marks the traditional start of the UK watercress season, however.

This year's sixth annual festival, at Alresford in Hampshire, will mark the bi-centenary of watercress growing. It will open with free cookery demonstrations by Antony Worrall Thompson.