RHUBARB 



193 



deep coldframes are then placed over them. The plant- 

 ing distances must be such as to best utilize space in the 

 frames. If the frames are 6 feet wide, there may be 

 three rows of plants running lengthwise in them, and the 

 plants may be 2 feet apart or even less than that if the 

 beds are given special care previous to the forcing period, 

 so that they will grow strong roots. 



Trenches heated by steam or hot manure, as explained 

 on page 184, may also be used, but it is doubtful whether 

 the plan is practicable when labor costs as much as it 

 does in the United States. 



In the Boston district, cheap permanent benches are 

 built over the rhubarb plantations, where the plants are 

 set about 2 feet apart each way. Such houses ordinarily 

 contain board walls. There are wooden rafters to sup- 

 port hotbed sash, placed to make either an even-span or a 

 shed form of roof. For use in winter, a few coils of steam 

 or hot water pipes are installed for the maintenance of 

 proper temperature. For use early in the spring, no heat 

 will be required in addition to that supplied by the rays 

 of the sun on the glass sash. At the close of the period 



Fig. 63. Rhubarb growing in coal ashes in an ordinary cellar. 



