Propagation by Cuttings. 199 



the pipes need to make many turns, steam is usually 

 more satisfactory than hot water. 



368, The Propagating Bed. A certain part of the 

 greenhouse is usually set apart for propagating plants 

 from cuttings. The propagating bed is made upon the 

 ordinary greenhouse bench, directly over the flue or heat- 

 ing pipes. To furnish the bottom heat (362 a), the space 

 beneath the bench is boxed in with boards. Horizontal 

 doors are, however, provided which may be opened when 

 it is desirable to allow a part of the heat to pass directly 

 into the house. The floor of the bench should not be so 

 tight as to hinder drainage. 



In large commercial establishments, entire glass houses 

 are often devoted solely to propagation. Such houses 

 are usually eleven or twelve feet wide, with low side 

 walls. Sometimes lean-to houses are built for propaga- 

 tion, on the north side of a wall, where direct sunlight 

 is cut off". 



In making the propagating bed, a thin layer of sphag- 

 num moss is usually spread over the floor of the bench 

 and covered to a depth of two to four inches with well- 

 packed, clean, rather coarse sand, brickdust or powdered 

 charcoal. Sometimes the whole bed is made of moss. 

 These materials are used because they will not retain an 

 excess of water if the proper provision is made for drain- 

 age. Sand is most used because it is as a rule readily 

 obtained, but it needs to be selected with care, as it often 

 contains injurious mineral matters. Sand found along 

 the borders of fresh- water streams or lakes may gener- 

 ally be used without washing, but that dug from sandpits 

 should in most cases be exposed to the air for a few 



