The volume of UK-produced asparagus could more than double as growers introduce new production techniques and increase the amount they plant in a bid to meet soaring demand.

The UK crop will have risen from 1,812 tonnes last year to 3,925 tonnes by 2010, claimed growers attending an asparagus industry conference this month. An increasing amount would be produced under cover using various types of polytunnel and heated glasshouse, they predicted.

Such methods have already extended the season beyond the usual eight weeks starting in May.

Asparagus produced in heated glasshouses by S&A Produce for Tesco hit shelves on 12 February and Sainsbury's also stocked early produce in March. To reflect the earlier start to the season, St George's Day - 23 April - has been designated the "official" start.

UK growers were also considering planting other varieti es, according to Piet Beutskens, sales manager at Limseeds, which has a 75% share of the European market. Limseeds currently produces the seeds for the Dutch-bred Gijnlim and Backlim varieties that form the backbone of the British crop. Another variety being trialled by UK producers is Avalim, introduced in 2004. While it doesn't produce the volumes of Gijnlim, it is said to produce a higher proportion of larger spears.

The industry is also throwing its weight behind a more aggressive marketing campaign. Adrian Barlow, chief executive of English Apples & Pears, has been drafted in to do a similar job raising the profile of asparagus as he has already done with apples and pears.

"Multiples are estimated to take 82% of the crop, but because of overall demand they still have to import 30% of their requirements. With consumer preference for British quality, this represents a major opportunity for the industry," Barlow told the conference.

"Customer penetration has increased to 14%, but 25% is realistic. So new production should not be seen as competition. If we get things right with the multiples it will lift up the results for everyone else."