I have a friend who owns blueberry farms (plantations?). He told me that shelf life can range from 7-30 days, and that the key to hitting the upper end of that is maintaining a relatively constant temperature throughout the supply chain (i.e. cold and cool are both fine, but you shouldn't switch between them).

Proof point (and an interesting experiment for me). We have a large bag of Italian parsley that we harvested from the garden at the end of August, before we went on a 10 day vacation -- in these parts, it will typically go to seed or die at that time of year if not watered and snipped constantly. My wife put it in a plastic bag with a paper towel to keep it dry, and stored in the refrigerator crisper drawer. We don't use a lot of parsely but I grabbed another small handful 2 nights ago. Its finally beginning to wilt a bit, and is at the end of its life after 3 months. Dry, cool storage seems important.

I'd love to see what would happen with home grown lettuce, but we eat it too quickly. I may have to explain that its for science which, if I'm lucky, will get me an eye-roll and passive acceptance. :)