CONSTRUCTION OF HOTBEDS I09 



should give all the protection needed by plants ordinarily- 

 grown in frames. (2) The labor in the management of 

 the frames is reduced, because there are no mats to be 

 handled morning and evening. (3) The plants receive 

 the light during the entire day, because there are no mats 

 at any time to obstruct it. (4) A growing temperature 

 is reached earlier in the day, and is maintained longer, 

 unless there is little or no sunshine. 



Disadvantages that may be mentioned are: (i) Double- 

 glass sash are much heavier to handle, and this is one 

 of the greatest objections raised by men who handle sash 

 by the hundreds. (2) They cost about one-third more. 



(3) On account of the accumulation and retention of 

 moisture between the two layers of glass, it is thought 

 that the sash will not be so durable as single-glass sash. 



(4) The two layers of glass and the accumulation of dirt 

 and moisture between the panes reduce the amount of 

 light entering the frames, and in consequence produce 

 weaker plants. This new type of sash can be used to 

 advantage for many purposes, although the single-glass 

 type will doubtless continue to be popular in sections 

 where hotbeds are used extensively. Oiled paper and 

 special waterproof cloth are substituted for glass some- 

 times. Although less expensive, they lack durability and 

 do not generally give as satisfactory results as glass sash. 



158. Manure and its preparation. — Practically all 

 manure hotbeds are made with horse manure. Poultry 

 and sheep manures are also desirable, although they are 

 too valuable in fertilizing garden crops to be used for this 

 purpose. Spent hops from breweries, and forest leaves, 

 may also be worked into the hotbed manure, which 

 should be fresh and not too compact nor too loose. If 

 it is composed almost entirely of the solid excrements 

 of the horse, with whatever urine it has absorbed, it may 

 fail to heat, or the fermentation may be too violent and 

 of too short duration. Two parts of excrement to one 



