Sweet Potatoes a Viable Crop for Northeast

Sweet potato crops grown at the UNH Woodman Horticultural Research Farm. Courtesy Photo.

Across America, millions of people will be sitting down at tables with turkey, stuffing and, most likely, sweet potatoes. While not a huge crop grown in NH, a recent study by the University of NH in Durham finds it’s a viable crop for the state.

“We demonstrated the potential to produce high yields of high-quality sweet potatoes, despite our relatively short growing season,” says Becky Sideman, a researcher with the NH Agricultural Experiment Station and UNH Cooperative Extension professor of sustainable horticulture production.

Between 2007 and 2012, sweet potato acreage in New England states increased more than eight-fold from four to 33 acres. Most individual producers have less than half an acre, according to the U.S. Department of Agriculture.

“It’s amazing. When we started this work, almost 10 years ago, no one was growing sweet potatoes at all [in New England],” Sideman says.

Sideman evaluated the performance of several different sweet potato plants grown at the UNH Woodman Horticultural Research Farm. Six types of plants were evaluated over four years, and an additional four cultivars were evaluated for two or three years.

Despite a relatively short growing season, the highest-yielding plants in each year produced 503 to 887 bushels per acre. That compares favorably with national average yields, which range from 310 to 550 bushels per acre depending on the state, with an overall average of 438 bushels per acre, according to the U.S. Department of Agriculture.

Sideman says the plant’s long storage life—up to one year in optimal conditions—makes it appealing for growers. “There are not a lot of crops we grow that you can successfully store past a few months,” he says.

One challenge to growing sweet potatoes commercially is the unique post-harvest management required, Sideman says. Sweet potatoes need to be cured at 80 to 85 degrees for a week and stored at temperatures of 55 to 60 degrees.

Lori Schreier of Fertile Fields Farm in West-moreland says her farm has a loyal following of sweet potato customers at farmers markets. “People are always asking when they will be ready for sale. They are being recognized as a super food, and people around here want to eat them more,” she says.

Fertile Fields Farm has been growing sweet potatoes for seven years and has sought out Sideman’s advice throughout the years on issues such as the condition of plants, fertilizer choices, use of plastic or row cover, and best planting practices.

Sideman says she does not know whether sweet potatoes will become a major crop in New England, but the results of the study are encouraging: that more growers could easily cultivate sweet potatoes. “It’s still what we call a specialty crop.”