Storing Heads of Lettuce
Leave heads intact and do not wash until you are ready to use them. Whole heads of lettuce will stay fresher much longer than chopped pieces or individual leaves. Remove any damaged or wilted outer leaves, then wrap in a few paper towels. Store in the crisper drawer of your refrigerator until ready to use.
Reviving Sad Lettuce
If lettuce is slightly wilted, it may be revived by submerging the leaves in a bowl of ice water. Let it sit for about 5 minutes, then remove and thoroughly pat dry. This will shock and crisp up the leaves.
While it will vary from one head of lettuce to another, when properly stored, leafy greens should stay fresh and crisp for 7 to 10 days. A whole head of lettuce will typically last longer than individual greens.