One of the most important things to keep in mind when harvesting sweetpotatoes is that the roots of the sweetpotato are alive. The roots require sufficient oxygen to survive, even in storage. Changes in the envi­ronment, such as temperature and rela­tive humidity, will affect the shelf life of the sweetpotato. Keeping these facts in mind will help you make good man­agement decisions for your sweetpotato crop.

Sweetpotatoes are usually stored in nonrefrigerated commercial or farm warehouses. This method of storing of­fers the primary advantage of orderly marketing several months after harvest­ing. After they are harvested, sweet­potatoes should be cured. Do not wash sweetpotatoes before curing or storing them. Curing promotes the healing of cuts and bruises that occur during har­vesting and handling. It also protects the roots from many storage diseases and excessive shrinkage while starches are being converted to sugars and other flavor components. Curing the roots in­creases the post-harvest life of the sweetpotato. To cure roots, hold them at 85 degrees F with 90 to 95 percent relative humidity (RH) for 4 to 7 days.

After curing, reduce the storage temperature to 55 to 60 degrees F at 80 to 85 percent RH. Most properly cured sweetpotato cultivars will keep satisfactorily for 4 to 7 months at this tem­perature and RH. Due to the sweet­potato’s tropical origin, roots will incur chilling injury if held at temperatures below 54 degrees F. Short periods at temperatures as low as 50 degrees F need not cause alarm, but after a few days at 50 degrees F or shorter periods at lower temperatures, sweetpotatoes may develop discoloration of the flesh, internal breakdown, off-flavors and hard core when cooked, and increased susceptibility to decay. Temperatures above 60 degrees F stimulate develop­ment of sprouts (especially at high hu­midity), pithiness, and internal cork (a symptom of a viral disease) when the virus is present.

Sweetpotatoes are usually stored in bulk bins or slatted crates. Palleti­zation of crates and use of pallet boxes facilitate handling. Some of the newer storage facilities equipped for pal­letized handling have separate curing and storage rooms. Sweetpotatoes can be cured in palletized field boxes in a room designed to provide recommend­ed conditions for curing. After curing, the sweetpotatoes can be carefully moved by forklift to rooms in which storage conditions are maintained con­tinuously. Refrigeration is now used in some large sweetpotato storages to ex­tend the marketing season into warm weather, when ventilation alone will not maintain low enough temperatures.

Sweetpotatoes are usually washed and graded, and sometimes waxed, be­fore being shipped to market. Roots should be treated with a fungicide to reduce decay during marketing. Consumer packaging of sweet­ potatoes in film bags or overwrapped trays is done mainly to aid marketing and should not be done before storage. The shelf life of washed and fungicide­-treated roots in consumer packs is only 2 to 3 weeks. Weight loss of roots dur­ing marketing is much less in perforat­ed film bags than it is in mesh bags.

Download a PDF of Harvesting and Curing Sweetpotatoes, ANR-1111.