GLASS STRUCTURES. 



65 



the bed is ready to receive the seed. A hotbed made up in 

 this way in March will continue to give out heat five or six 

 weeks, after which it will be practically a cold frame, but since 

 after the middle of April the sun is pretty high and the bed 

 well warmed, the plants will continue to nourish. 



Hotbeds require more water than cold frames and more 

 care in the matter of ventilation. They should not be started 

 until a short time before one is ready to use them. If seed- 

 lings are to be raised in them to be later on transplanted, 

 start only enough sashes to grow the seedlings and do not 

 start other hotbeds until the seedlings are big enough to be 

 removed into them. 



For the ordinary farm garden four or five hctbed sashes 

 is a great plenty, and no more should be started than can be 



Figure 25.— Fire hot-bed. 



properly attended to. These should be started about the first 

 of March. This number will be found sufficient for all the 

 early radishes, onions, lettuce, cress and other greens for the 

 table in early spring, and for raising tomatoes, cabbage and 

 other vegetable plants to be set out later on in the open 

 ground. 



Shutters and mats are used for covering the sash of hot- 

 beds and cold frames at night to prevent too rapid radiation 

 of the heat. 



