172 PRODUCTIVE FARMING 



spring from seed potatoes. The whole potatoes are planted 

 in fine, rich sandy loam in hot-beds (Figs. 88, 89). These 

 may be heated either by manure or by fuel. The tempera- 

 ture at first is kept at 80 or 85 F. Before the plants are 

 pulled from this bed to be transplanted to the field the 

 temperature is gradually lowered to 60 F. The growth in 

 the hot-bed requires about six weeks. 



PIQ. 88. Sweet potatoes in a hot-bed ready to be covered. They will produce 

 young plants for field planting. (Experiment Station, N. J.) 



In the Field. The soil is prepared as for corn the sur- 

 face being left smooth and even. In some places the farmers 

 ridge the field and set the plants on the ridges. Others 

 practice the level culture. Planting in the field should be 

 done when the soil is moist enough to produce a rapid growth 

 after setting the young plants. Where level culture is prac- 

 ticed the plants are often set two or two and one-half teet 

 each way. Where ridges are made the rows are often three 

 and one-half feet apart and the plants fourteen to eighteen 



