CHAPTER XVI 



GLASS STRUCTURES AND CARE OF GREENHOUSE 



CROPS 



IN producing early vegetables glass structures are es- 

 sential. These are used both as a means of starting plants 

 early in the spring and of growing crops during the winter 

 season when it is impossible to produce them out of doors. 



Hotbeds. Hotbeds are the simplest and cheapest forms 

 of heated glass structures. A well-drained spot, protected 



Fig. 189. Cross section of a hotbed. 



from the north and west, conveniently located, and acces- 

 sible to a liberal supply of water, are the essential condi- 

 tions governing their location. The heat furnished the 

 beds is usually produced by the fermentation of manure. 

 Since from fifteen to thirty inches of manure is required, a 

 pit should be dug one and a half to three feet deep. For 

 starting plants that require high temperature for a long 



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