68 The Sweet Potato 



to have the hotbed extend east and west as the sun-rays 

 concentrated by the glass will be of substantial value in 

 supplying heat. Sash-bars or cross-rafters to slide the 

 sash on may or may not be used ; if the walls are prop- 

 erly supported at the comers and at intervals along the 

 sides by 2 X 4 inch stakes driven into the ground, cross 

 rafters are not essential. 



A layer of fresh horse-manure at least 12 inches 

 deep is placed in the pit a week before bedding the 

 potatoes and thoroughly packed by tramping. Manure 

 which contains old sweet potato refuse or culls from 

 the storage-house should be carefully avoided as dis- 

 eases may be conveyed in this manner. Before using, 

 the manure should be piled and forked over two or three 

 times to insure uniformness throughout. In case the 

 manure is dry, it should be watered, as moisture is an 

 essential to the decomposition which produces heat. A 

 layer of clean sand 3 or 4 inches deep is spread evenly 

 over the manure as soon as heating starts. This sand 

 should always be obtained fresh from the woods, a pit, 

 or some place where it has had no chance to become 

 infected with disease. Some of the most serious dis- 

 eases develop in the plant-bed and every precaution 

 should be taken against their introduction. Fresh 

 sand should be used for bedding each season, as disease 

 may remain in the sand and carry infection over until 

 the next year. The woodwork of old beds should be 

 sprayed each year as a precaution against disease. 



After the bed has been prepared, it is best to place 

 the sash in position and allow the heat to become con- 

 stant before the seed are bedded. When the tempera- 

 ture has dropped to 80 or 85 degrees F., the tubers are 



