448 GARDEN FARMING 



about 1 2 to 1 8 inches deep, in the bottom of which are steam pipes 

 with perforations T a g inch in diameter every 2 inches. The perfora- 

 tions are arranged to come on the underside of the pipes, which 

 are in coils and far enough apart to allow the blade of a spade to be 

 operated between them. The boxes should be made large enough to 

 hold one or two cartloads of compost, and should have lids which 

 are carefully fitted to the boxes. After subjecting the soil to the 

 action of the steam a sufficiently long time to cook a potato buried 

 in it, it will be thoroughly sterilized. If a more permanent structure 

 than the box is desired, a brick pit 1 8 or 20 inches in depth can 

 be arranged for the purpose. The bottom should be paved or con- 

 creted, and the side walls made at least 9 inches thick and coated 

 with cement to make them as nearly air-tight as possible. Good 

 drainage should be provided, and a tight-fitting lid will be necessary. 

 Better than this type of pit, however, is one shallow and broad or 

 long rather than deep, as the sterilization will be accomplished 

 sooner in a comparatively shallow layer of soil than in a very deep 

 one. 1 After the soil has been sterilized or after the compost has 

 been made as first described, it should be spread upon benches so 

 constructed as to admit of placing steam or hot-water pipes beneath 

 them in order to produce the desired amount of bottom heat. To 

 secure the greatest economy of both labor and space, the heating 

 pipes may be placed close to the surface of the ground, and the 

 bed constructed only a few inches above the heating pipes, thus 

 making a small air chamber not more than 10 or 12 inches 

 deep between the bottom of the bed and the top of the floor or 

 ground. With such an arrangement and adequate openings along 

 the sides, the heat given off by the pipes beneath the bed will pro- 

 duce a sufficiently high temperature for the tomato. While best 

 results are undoubtedly secured from the use of bottom heat, a 

 large part of the tomato forcing houses are built with solid benches 

 and no bottom heat. 



Growing the plants for forcing. Two types of plants are used 

 for forcing purposes seedling plants and cutting plants. The 

 seedling plants are those grown specially for greenhouse culture. 

 It is customary in the latitude of New York and northward to 

 sow the seed for a forcing crop between August I and August 1 5 . 



1 See also the description of the Shamel sterilizer, page 25. 



