From Dr. Joseph Mercola.
Once vegetables are picked they begin to lose nutrients. While there is no way to avoid this loss – other than 
growing the vegetables yourself and eating them right from the vine – you can easily increase the staying power of your vegetables by storing them properly.
The key is to keep as much air away from the vegetables as possible once you get them home. To do this, simply squeeze as much air as you can out of the bag that holds the vegetables and then seal it. The bag should look like it is vacuum-packed. This will double or triple the normal storage life of the vegetables.
Washing your vegetables is also important. This is especially important if you are unable to obtain organic vegetables, as you will want to remove as much of the pesticide residue as possible. Don’t worry if you can’t buy organic – any vegetables are better than no vegetables at all. To clean your vegetables, soak them in a sink full of water (ideally this should be filtered water, not tap) with 4 to 8 ounces of distilled vinegar for 30 minutes.
