"We should take care not to cheapen the product by reducing quality - for example, through planting on bad sites - or by selling on price just to get some money back," he said.
"It's not an industry to invest in if you expect short-term profits or require financial leverage on your investment," he added.
There has already been a 45 per cent growth in the hectarage of English vineyards in the past five years, delegates heard.
An English Wine Producers representative said: "The popularity of sparkling wine has dictated that it is Chardonnay, Pinot Noir and Pinot Meunier being planted."
But she added: "Outside the South East, that could be more difficult. Growers need to do their research on soil conditions and varieties. It's vital that what comes through is of quality."
She pointed out that 2011 was "high on quality, but lower on volume than expected", although final figures will not be confirmed until spring.