by SCMG Betsy Karrer
In grocery stores, “sweet potato” and “yam” often are used interchangeably. My question always has been, “Which vegetable am I buying?” Are they the same thing? The answer is yes and no. The USDA requires that the label “yam” also include “sweet potato.” Therefore, most “yams” found in U.S. grocery
The sweet potato (Ipomoea batatas) is the tuberous root of a trailing vine that quickly covers the soil, rooting at the nodes along the way. It needs sandy soil and a long frost-free growing season (120-240 days). It is possible to grow sweet potatoes in warmer areas of California. This crop may not be successful in the coolest microclimates in Sonoma County.
There are two types of sweet potatoes: one with yellow skin and dry, whitish flesh and a darker skinned potato with moist, sweet orange flesh. Orange flesh varieties recommended by Sunset Western Garden Edibles include ‘Centennial,’ ‘Jewel’ and ‘Kona-B’ as well as two bush types that take less space: ‘Vardaman’ and ‘Vineless Puerto Rico.’
Sweet potatoes are cultivated with the use of “slips” which are cuttings from
Harvest the tubers before frost, late in the fall. Stop watering and allow the soil to dry just before harvest. The young green leaves and stems of the plant are edible as well. According to Pam Peirce in Golden Gate Gardening, cure the sweet potatoes by putting them in a warm humid place (80 degrees) for two weeks. Then, wrap each root in newspaper and store at about 55 degrees. They get sweeter after curing.
A quarantine in California to ward against the sweet potato weevil means that you cannot order sweet potato roots from most sources outside the state. Sources for organically-certified, clean, rooted slips can be found in Pam Peirce’s gardening reference or you may consult your local nursery. Two diseases, black rot and scurf, can attack sweet potatoes as well as the usual insect pests who are attracted to green growth and vertebrate pests who eat root vegetables. A good reference for pest control is UC Davis’ Integrated Pest Management page.
The sweet potato is quite nutritious and has no fat. A serving has three grams of fiber. Orange and yellow varieties of sweet potato are high in vitamin C and