One of the limiting factors for dry matter production in sweet potato (Ipomoea batatas Lam.) is the establishment of cut-sprouts or cuttings. To improve the establishment of cut-sprouts, factors affecting the rooting of cut-sprouts were investigated. First, the effect of the soil temperature on rooting was investigated. The optimum soil temperature for rooting and varietal differences, varietal differences in rooting ability at a low soil temperature, and the effect of high soil temperature stress on the rooting were analyzed under controlled environment. The effect of vinyl mulching on rooting and the formation of tuberous roots was analyzed under field conditions. Second, the effect of holding (storage) of cut-sprouts on rooting was investigated. Beneficial effect of holding for 5 to 10 days on the rooting, formation of tuberous roots and yield was revealed. The physiological mechanisms of the beneficial effect of holding were also analyzed.