Fresh vegetables wilt because of falling moisture content. As water evaporates from the produce, cell walls lose rigidity. The vegetables become soft and flexible and vitamin content drops. Wilting does not make fresh vegetables inedible. Intentionally drying vegetables preserves much of the nutritional value and flavor during long-term storage. Wilting could signal plant disease or rot. Portions of some wilted and discolored vegetables could be saved by careful trimming.
Wilting in the Garden
Wilting plants in the garden might fully revive after a thorough watering, but wilted yellow leaves and discolored leaves and stems indicate more serious problems. Many diseases working both above and below ground discolor and wilt leaves and affect the health and food value of the entire plant. Diseased produce rots quickly, so discard any part of the harvest damaged by bacterial, fungal or viral wilt. Weakened plants could produce small fruits of poor quality. If blights don't respond to sprays, destroying the plants and replacing them with a different crop could help prevent the spread of the disease.
Wilting in Storage
Unprotected fresh vegetables stored in a dry environment lose water and wilt quickly. Some volatile vitamins evaporate along with the water, but minerals, carbohydrates and many other nutrients remain. The flavor of fresh wilted vegetables changes, but wilted produce in otherwise good condition makes good soup, stew or stir-fry. To prevent wilt, refrigerate fresh vegetables and keep the refrigerated produce in plastic bags. Cut leafy tops of carrots and beets back to a half inch from the crown to stop the loss of root moisture through leaves. The tops of root vegetables could wilt and rot without affecting root quality.
After long periods of storage, produce wilts because of cell death rather than water loss. Fungi and bacteria accelerate the rotting process and cause chemical changes in the food. Toxins from fungi spread far from the visible infection in vegetables with a high water content, such as salad greens and cucumbers. Trimming out wilted and moldy sections of firmer vegetables, such as cabbage, carrots and broccoli, could save most of the food. Trim moldy parts an inch past the edge of the mold and don't touch the moldy section with the knife blade, recommends Baylor College of Medicine.
For anyone on a tight budget, using as much of the food you buy as possible makes good sense. Buying smaller quantities of fresh produce and using the produce quickly helps avoid problems with wilt and reduced food quality. Inspect produce before purchasing and set aside any that shows wilt or other signs of age. Bulb onions and potatoes store for months without refrigeration, and refrigerated carrots last up to three weeks. Cabbage heads keep for two weeks in the refrigerator. Most other vegetables have a shelf life of less than a week, and many last only three to five days.