Growers in California's San Joaquin Valley are preparing for freezing temperatures tonight and what may be at least one sleepless night as a cold weather mass from Alaska moves over the state.

The crop of concern is citrus, much of what remains unharvested. Because of their sugar content, oranges can take about four hours of temperatures of 28 degrees with minimal damage. Lemons are more susceptible to freeze damage because they don't contain as much sugar.

To view the full story in the San Francisco Chronicle, click here.