Tomato prices are on the rise and shortages have been reported at some restaurant chains in the United States due to an unusually cold winter growing season in Florida.

The Sunshine State lost 70 per cent its tomato crop during a devastating January cold snap that saw temperatures plunge as low as -17 Celcius in the state capital of Tallahassee.

Since then, wholesale prices in the U.S. have jumped by as much as five times. And some American restaurants have cut back their tomato orders.

"The tomato prices definitely have gone up, and the quality isn't so great either," said Matthew Villareal, manager at Costello Sandwich and Sides in Chicago. "We just kind of eat the cost."

Florida's usually exports 11 million kilograms of tomatoes per week. But exports have fallen to less than a quarter of that, said Reggie Brown of the Florida Tomato Grower's Exchange.

As a result, the average wholesale price for an 11-kilogram box of the fruit has jumped from US$6.50 last year to US$30.

Fresh tomatoes cost consumers an average of US$1.64 a pound during the week of March 4, according to the U.S. Department of Agriculture. That's 22 per cent more than during the same week in 2009.

The shortage was being felt by some American fast-food customers. Signs were posted at Wendy's restaurants saying tomatoes would be provided only if a customer requests them due to limited availability.

Smaller businesses were taking similar steps.

"We're a little more careful with our tomatoes," said Bill Murphy, owner of Murphy's Red Hots in Chicago. "You still owe it to your customers to get them out there and get them on the dogs. You try to get an extra piece out of every tomato if you can. You don't toss them around like they're pennies, you toss them around like they're quarters."

Other U.S. states grow tomatoes year-round in greenhouses, but Florida's crop is by far the country's largest, making persistent cold weather in there particularly bad for tomato suppliers.

"Anecdotally, from talking to some real long timers, as well as people who watch the weather, this has been the most extended cold in maybe 60 years," said Terry McElroy, spokesman for the Florida Department of Agriculture.

Brown said he had been hoping the state's surviving tomato crops would recover by the beginning of April. Now he's hoping for mid-April.

With files from The Associated Press