24 GREENHOUSES 



steam pipes may be run through these flues 

 if desired, or they may be placed along the 

 sides of the frame above the soil. 



COLDFRAMES 



The forcing house, because of its conveni- 

 ence, possibility of heat regulation and com- 

 parative cheapness of operation is rapidly 

 taking the place of the hotbed in a commer- 

 cial way in the starting of early plants, but 

 it is promoting the use of coldframes. These 

 structures rarely receive artificial heat and 



Fig. 10. A good type of coldframe with angle iron 

 corners, A. 



are used largely for the purpose 'of growing 

 and protecting plants during mid or late 

 spring, after they have been started in the 

 hotbed or forcing house and until they are 

 ready to plant in the open. They are, . in 

 reality, simply hotbeds without artificial 

 heat. When banked with manure and pro- 

 tected with mats, these frames will protect 

 tender plants at temperatures of 15 or 20 de- 

 grees below freezingj if of short duration. 



