60 THE USE OF GLASS 



Greenhouses furnish the most ideal conditions for starting 

 early vegetable plants, for in a properly constructed house any 

 desired temperature can be maintained to a nicety no matter 

 how cold the weather (Fig. 33). Greenhouses can be used for 

 growing certain crops to maturity in the dead of winter, as well 

 as for starting early plants to be later transferred to coldframes 

 and the open ground. In addition to the better control of tem- 

 perature, another great advantage of a greenhouse over hotbeds 

 and coldframes for starting early plants is that the gardener can 

 give the plants better attention in bad weather. On stormy 

 days, when it may be entirely impracticable to work at plants in 

 hotbeds, the gardener can go into his greenhouse and give the 

 plants the attention they need. It is a decided advantage to the 

 gardener and to the plants if both can be under the same roof when 

 the weather is bad. 



The advantages of hotbeds and coldframes, as compared with 

 greenhouses, are their cheapness of construction and cost of main- 

 tenance, and the facility with which they can be thoroughly venti- 

 lated (by removal of the sash) when the warm days of late spring 

 arrive. A spring crop of lettuce is more certain to develop prop- 

 erly in a coldframe than in a greenhouse. On the whole it may be 

 said that each type of glass structure has its place in vegetable 

 gardening operations and none can be fully substituted for the 

 others. 



CONSTRUCTION OF MANURE HOTBEDS* 



A manure hotbed may be made very cheaply by placing a 

 sash-covered frame on top of a flat pile of fermenting manure 

 (Fig. 34). However, such a bed is badly exposed to winds, and is 

 less satisfactory in cold weather than a bed made by placing the 

 frame above a pit containing the manure. The pit may be merely 

 an excavation in the ground or may be walled up with plank, 

 or even brick if a permanent bed is desired. The bed must be in 

 a well-drained location if the manure is placed in a pit; otherwise 

 water would likely seep into the pit and interfere with the proper 

 fermentation of the manure. 



The preparation of manure for a hotbed should begin at least 

 three weeks before the hotbed is to be used. Fresh horse manure 

 from grain-fed animals should be placed in a compact pile. The 



* Directions for the construction of both manure and fire hotbeds have 

 been adapted from Illinois Bulletin No. 144, 



