Livingston, California's sweet potato packing sheds store sweet potatoes for up to a year. Each year's crop is harvested from late August into early October. They are kept in the dark, in either 20 pound bins or 1,000 pound bins, in dry warehouses with temperatures of about 55 - 59 degrees Fahrenheit.
A noticeable percentage of the sweet potatoes go bad each month. (When sweet potatoes rot, they release moisture, which can help adjacent sweet potatoes also go bad.) Depending on the quality of the sweet potatoes, they are shipped to six different kinds of customers:
- Packing shed workers, who can take the pick of the crop home to their families as a perk.
- High quality groceries that insist on only getting the best. These grocery stores pay higher prices per pound.
- Good grocery stores.
- Grocery stores that only inspect the top layer of some boxes. (Each box contains 40 pounds of sweet potatoes. Ironically, some of these stores brag about the quality of their produce.)
- Companies that make candied yams. (They cut off the bad parts of sweet potatoes, and seriously cook the remaining parts.)
- Pig farmers.
The storage conditions matter. If sweet potatoes are stored in an environment (without air conditioning) that fluctuates between 70 - 105 degrees Fahrenheit, even handpicked sweet potatoes taken home by the packing shed workers will only last a week. Whereas pristine sweet potatoes from a high-quality grocery stored in a dry environment that fluctuates between 60 - 70 degrees Fahrenheit often last three weeks -- even after being trucked 3,000 miles. Worse quality sweet potatoes may last 4 - 10 days.