62 THE PRINCIPLES OF FLORICULTURE 



battens and braces. The form is only temporary, being 

 removed as soon as the concrete sets. Sometimes it is 

 not necessary to place a form on the outside face of the 

 sub-frame. The soil at the back is cut down, making a 

 straight, even surface. This holds the concrete in place 

 until it sets. 



The standard mixture for concrete is one part cement, 

 two parts clean, sharp sand and five parts broken stones, 

 cinders or some similar material. This concrete is 

 poured into the frame and tamped securely in place, care 

 being taken that the finer mixture is against the outside of 

 the form, thus making a smooth surface. Cross strips of 

 two-by-three inch material are embedded in the top of the 

 frame, before the concrete hardens. They are spaced 

 every three feet and serve to support the sashes after they 

 are placed. In making the concrete hotbed, it is necessary 

 to board both sides of the form above the grade. The 

 height of the frame above ground is usually the same as 

 that described for the steam-heated frame. When once 

 in place, the concrete hotbed is practically indestructible, 

 provided it is well made. A concrete hotbed such as 

 the one described, twenty-five feet long by six feet wide, 

 should be built for approximately 813.50; this would re- 

 quire eight sashes. The cost of the foundations and frame 

 above ground for each sash would therefore be about SI. 62. 



The next best material, from the standard of durability, 

 is probably bricks, but while very satisfactory, brick frames 

 are not so easily made as the concrete frames. Chestnut 

 and cypress are the two most lasting woods. Two-inch 

 plank is used for the sides of the frames, and two-by-four 

 inch material for the battens and braces. Hotbeds may 

 be used as coldframes if decomposing manure is not 

 needed for heating the soil. Deep frames of this sort 



