Reprinted from Virginia Cooperative Extension Service Sweet potatoes are not true yams - they belong to the morning glory family, while true yams belong to the plant family which grows only in the tropics. The true yam is rarely available anywhere in the United States even though some say a few may be found in the extreme southern part of the country. Plant traditional vining type sweet potatoes in raised ridges, in light, deep, loose soils.
Ridges permit fast growth of smooth, properly shaped roots and make digging easier.
Set plants when danger of killing frost has passed. Leave 6 to 8 inches between them and 3 feet between rows. Harvest before frost - handle roots carefully to prevent cuts, bruises, and broken roots. Use sweet potatoes soon after harvest.