Harvesting and Curing Sweet Potatoes
Anxious to harvest sweet potatoes? Hold off! While you can technically harvest as soon as the tubers reach a decent size, the longer they are in the soil the sweeter and higher in vitamin content the sweet potatoes will be.⠀
Ideally, gardeners should wait until right before the first frost to harvest to achieve the best flavor. This requires you to watch for when frost is predicted and harvest right before that. Sweet potatoes can survive a frost but since they are a tropical plant, there is always the risk that a frost will kill the vine which will cause them to start rotting in the ground. (We typically harvest our sweet potatoes in late October depending on the timing of the first frost.)
While sweet potatoes can be eaten straight from the ground, you are likely to be disappointed in the flavor. Curing triggers the sugar-producing enzymes and heals nicks, so skipping this step results in starchy, tasteless sweet potatoes with limited shelf life.
Curing is a two step process. First, leave the tubers in the sun for several hours to dry the skin in order to prevent rotting during the next step. Then move the potatoes to a warm, humid place for 4-10 days. This is when the starch is converted to sugar. Ideal conditions for this step are 85-90°F and 85% humidity. A hoop house usually provides optimal conditions but a pantry with a small bucket of water and space heater will achieve this (keep an eye on the temperature). The closer you get to those ideals the better but those two options aren’t always the most practical for gardeners. We have also seen success form those who lay their sweet potatoes out in a sunroom or porch where there is plenty of air and protected from rain. We have even met people who have had success laying them on their dining room table with a fan running. No matter how you do it make sure to regularly check the sweet potatoes and get rid of any that are spoiling. At the end of the curing process, place them in a cool spot for storage. Ideal conditions are 55-60°F and 75% humidity. Basements frequently approximate these conditions.