Start sweet potatoes indoors six to eight weeks before average last frost in your area. These plants require 100 to 110 days of frost-free growing, and do well with early starts for a longer season.
Push five to six long toothpicks into the middle to top one-third of the sweet potato, angled outward. These provide your supports for growing.
Fill a large glass or jar with water. Stick the pointed end of the sweet potato in the water and leave the toothpicks resting on the rim. The top one-half or one-third of the sweet potato should stick up out of the jar or glass.
Put the jar in a warm, sunny location for rooting. Mix water-soluble 10-10-10 fertilizer into the water for potato nutrition and maintain an adequate water level until transplant.