Located in a rural area of Lexington County, SC, is a dilapidated sweet potato drying house. If you’re unfamiliar with the concept of a sweet potato drying house, welcome to the club. I, too, had no idea such a structure existed until I happened across it recently.
From its appearance, it’s safe to say that it’s been many a year since any sweet potatoes were cured in the rectangular wooden structure. The building has a single door, four openings in the roof, and four small windows and one larger window. It was definitely not built for comfort.
Estimating its age is inexact at best, but because it was built with round-headed nails it was almost certainly built after 1890 and, from its appearance, most likely before World War I.
The structure recently achieved higher visibility because, after many years of being surrounded by thick woods, the land surrounding it was cleared, leaving it sitting in the open.
When constructed, sweet potatoes were a staple of the American diet. At the beginning of the 20th century the tubers were the second most-important root crop in the nation. Per-capita consumption of sweet potatoes in 1920 was 31 pounds, but by the start of the 21st century that figure had dwindled to just 4 pounds per person, according to the US Department of Agriculture.
Storing sweet potatoes is a relatively straightforward. The bottom line is to cure the tubers, than keep the potatoes dry, to fend off rot, and prevent them from getting too warm or too cold.
The main goal behind curing is to heal injuries so that sweet potatoes remain in good condition for marketing during the winter and to preserve “seed” roots for the next crop, according to the Cooperative Extension Service at the University of Georgia College of Agriculture.
Healing takes place rapidly at 85 degrees Fahrenheit and between 85 to 90 percent humidity, for four to seven days.
Sweet potatoes in all their glory.
“Curing should start as soon after harvest as possible to heal injuries before disease-producing organisms gain entrance,” according to the Georgia Cooperative Extension Service. “Healing involves production of cells that are very much like the skin in their ability to prevent infection. These new cells form in a layer just below the surface of the injuries. Because this layer is corky, it is commonly called wound cork. Healing is more rapid under clean cuts and skinned areas than in deep wounds where tissue is crushed. The rate of healing differs a little among varieties.”
In the above structure, heaters and exhaust flues were used to promote circulation, remove excessive condensation and prevent accumulation of carbon dioxide produced by sweet potato roots.
The four holes in the roof were used to vent the flues.
After the tubers were cured, the temperature in the storage house was brought down to a narrow range of between 55 and 59 degrees Fahrenheit, with relative humidity maintained at between 85 and 90 percent.
Much below that and sweet potatoes experienced an increased susceptibility to rot and discoloration, and the quality of roots was diminished, hurting their ability to produce sprouts when planted the following season.
It’s unclear how common standalone sweet potato drying houses were. It’s likely most individuals who raised the tubers simply relied on earthen structures, whether dug into banks or put into holes then simply covered with dirt.
Standalone structures like the one shown above would likely have been used by more than one farmer, a cooperative of sorts, or by an individual with an extremely large spread.
(Top: Old sweet potato drying house, located in rural Lexington County, SC, west of Columbia.)