The optimum planting date, plant spacing, and harvest time for production of small-sized sweetpotato was evaluated in 2003 to 2004 at the Mokpo Experiment Station. Small-sized sweetpotato is important as snack food in Korea. Optimum planting date and plant spacing were with plastic mulch, and mid-April and 75×15~20 cm respectively, mid-June and 75×15 cm respectively without plastic mulch. Storage root yield decreased with early harvest, but the ratio of small-sized sweetpotato was higher in plots harvested after 100 days of planting (DAP) than that of 80 or 120 DAP. Considerable differences in storage root yield was noted with planting dates and plant spacings, but the use of plastic mulch resulted to smaller yield variations in plots, harvested in mid-April. Planting in mid-April and harvesting after 100 DAP increased income by about 32~61% compared with plantings midMay.