Flower prices may rise and bouquet sizes get smaller as suppliers try desperately to mitigate soaring costs, growers have warned.

Rocketing fuel costs have made the cost of heating glasshouses unsustainable, claimed a leading UK flower grower, who asked not to be named. Gas and oil prices have more than doubled since last year, with the South Ossetia conflict threatening to send fuel costs even higher.

At current levels retail price rises of at least 12% were needed to make the glasshouse production industry sustainable, said the grower. “If I don’t get an increase in price soon then I won’t be turning on the generators this winter,” he added. “I may as well just write a cheque to my supermarket customers otherwise.

“The only person who can resolve this is the consumer. They have to accept higher prices.”

Another option under consideration was to decrease the number of flowers in a bouquet, he said. That would mean the number of stems in a typical bouquet of cut flowers could fall from five to four in winter, or from seven to six in summer.

Pot plant growers producing under glass were also struggling, said Philip Austen, chairman of the British Protected Ornamentals Association, with some companies being forced to reassess their futures.

“Those growers using the most energy, such as orchid growers, are seeing a massive rise in their energy bills,” he added. “If there’s to be a sustainable industry here the prices will have to go up. They’ve been too low for too long.”

Dutch growers were also struggling with huge fuel bills, he said.

Although producers in naturally warm countries such as Kenya, Egypt and Colombia depended upon natural sunlight rather than glass, their airfreight costs had increased massively, meaning retailers could not simply expect to switch to cheaper imported varieties.