GREEN-HOUSE STRUCTURES. 115 



and the manure become of the proper " sweetened " con- 

 dition. It is economy of the heating material to use a 

 pit for the hot-bed. This should be made from two to 

 three feet deep, six feet wide, and of any required length. 



After the heating material has been packed in the pit 

 to the depth of twenty to twenty-four inches, accord- 

 ing to the purpose for which it is wanted, or the season 

 of the year, (the earlier in the season, the deeper it is 

 needed,) the sashes should be placed on the frame, and 

 kept close until the heat generates in the hot-bed, which 

 will usually take twenty-four hours. Now plunge a 

 thermometer into the manure, and if all is right it will 

 indicate 100 degrees or more ; but this is yet too hot as 

 bottom heat for the growth of seeds or plants, and a few 

 days of delay must be allowed until the thermometer 

 indicates a falling of 8 or 10 degrees, when four or five 

 inches of soil may be placed upon the manure, and the 

 seeds sown or plants set out in the hot-bed. Amateurs 

 are apt to be impatient in the matter of hot-beds, and 

 often lose their first crop by sowing or planting before 

 the first violent heat has subsided. Another very com- 

 mon mistake is in beginning too early in the season. In 

 the latitude of New York nothing is gained by beginning 

 before the first week in March, and the result will be 

 very nearly as good if not begun until a month later. 



There are two or three important matters to bear in 

 mind in the use of hot-beds. It is indispensable for 

 safety to cover the glass at night with shutters or mats 

 until all danger of frost is over ; for it must be remem- 

 bered that the contents of a hot-bed are always tender, 

 from being forced so rapidly by the heat below, and that 

 the slightest frost will kill them. Again, there is danger 

 of overheating in the daytime by a neglect to ventilate 

 when the sun is shining. As a general rule, it will be 



