It’s easy to forget about sweet potato plants. Once established and mulched they don’t require much from a gardener. They quickly carpet their allotted space, have few leaf and stem problems (see small holes from tortoise beetle feeding in photo below), and are drought tolerant. As the days shorten I start to think about fall dishes and desserts, and the sweet potato plants in my garden.
Websites and books tell you that sweet potatoes are ready to harvest 90-120 days after planting. But the only way to know for sure is to gently loosen the soil and take a peek. I did this on Labor Day and unearthed a few skinny roots. I returned with garden fork on September 16th and was happy to see that it was harvest time.
I located the main stem for each plant and cut all of the vines growing from the base of the main stem (crown). I like to insert a sturdy twig or stick of some sort next to each slip that I plant in the spring. It makes finding the main stem much easier!
I moved aside the straw mulch and loosened the soil in a ring about 2 ft. from the main stem. Then I gently lifted each crown and moved my fingers through the loose soil to find other harvestable roots. Some were 1 ft. down! Handle each root very gently to avoid skinning injury.
I left the sweet potatoes lying on straw for a day and then moved the roots, with soil still attached, to the porch. I’ll let them “cure” hear for five or six days. Scrapes and small cuts will heal over and some of the root starch will convert to sugars. Ideally, this would happen at a constant 80-85⁰ F. air temperature and 90-95% relative humidity. Luckily, we’re having some warm, humid weather. The first sweet potatoes I use in the kitchen will be those I accidentally sliced during harvest.
An ideal long-term storage area for keeping the roots would be maintained at 55-60⁰ F. and 85% relative humidity. I’ll store the roots in my basement where it’s warmer and drier than ideal. These “short-of-the-mark” curing and storing techniques sill provide sweet, flavorful roots that last through most of the winter.
By Jon Traunfeld, Director, Home and Garden Information Center