OLASS STRUCTURES 



95 



bed will depend very much on the season of the year at 

 which the bed is made up, and the crop to be grown. In 

 the colder Northern states when the hotbeds are made up 

 at the beginning of March, from 24 to 30 inches of manure 

 should be used, and covered with six or eight inches of 

 rich soil. Later in the season 18 inches or even one foot 

 of manure may be sufficient. In favorable locations 

 hotbeds may be used all winter for growing lettuce, radishes, 

 etc. This is not often practicable in the extreme Northern 

 states, and cheap greenhouses are generally used there 

 during winter and hotbeds only during the spring. 



Fig. 34. A cross section of a hotbed. 



The hotbed and frames for early spring use should be 

 prepared in the autumn, so that no digging will have to be 

 done in the spring. The soil for spring use should generally 

 be put into them, covered with leaves, and the shutters and 

 mats put on to keep out the frost. If this has not been done 

 the sash may be put on in the early spring, which will par- 

 tially thaw out the soil in the bed; or, by another method, 

 more manure may be used, putting it on the surface of the 

 frozen land, and the frame may be set on top of it. In the 

 latter case the manure should extend at least one foot beyond 

 the sides of the frame and be one-half again as deep as when 

 placed in a pit, and the frame should be banked up with 



