How should lettuce be stored?

Lettuce should be stored at a temperature of 40°F. or lower within two hours of purchasing. A head of lettuce needs to be wrapped to protect it from other refrigerator odors and  dehydration. It  should be loosely wrapped in plastic film or placed in a perforated bag.  These materials will help reduce dehydration and won't allow the growth of dangerous bacteria such as the one that causes botulism. 
 
Don't store lettuce at or near freezing. Moisture in the lettuce will turn to ice and destroy the lettuce's cellular structure. When brought closer to room temperature, the lettuce leaves will be wilted and perhaps even slimy.
 
Source(s):
FDA "Safe Handling of Raw Produce and Fresh-Squeezed Fruit and Vegetable Juices"
 
Susan Brewer, Ph.D. University of Illinois, Department of Food Science and Human Nutrition