414 VEGETABLE FORCING 



houses make beds 10 to 12 inches deep sometimes, but this 

 is of doubtful expediency. The more generally approved 

 plan is to use only the specially composted manure, mak- 

 ing beds with a total depth of 8 to 10 inches, after the 

 manure has been firmed or compressed by the use of a 

 board or other convenient device. A certain amount of 

 compacting of the manure is necessary to prevent it from 

 becoming too loose and dry. 



After the beds have been filled, the temperature of the 

 manure may rise for a few days and then it will begin to 

 decline, but there should be no spawning until it is down 

 to 75 degrees or preferably 70 degrees. The moisture of 

 the beds between filling and spawning should also be 

 carefully watched. If the manure has been properly pre- 

 pared and the beds and houses are well constructed, 

 there should be very little trouble in this connection. 

 However, light sprinkling is sometimes necessary in 

 order to maintain proper moisture conditions. A practi- 

 cal test is to squeeze the compost in the hand at the time 

 the beds are filled. If no drops of water are squeezed out 

 and the hand remains distinctly moist, additional water 

 is not required. But too much emphasis cannot be placed 

 upon the importance of having perfect moisture condi- 

 tions when the beds are filled. Skillful growers never 

 water the manure in the beds. 



Spawn. Success in growing mushrooms depends very 

 largely upon the use of good spawn. English spawn was 

 used almost exclusively in this country until a few years 

 ago, and although it was regarded as the best, results 

 from its use were very uncertain. Great credit is due 

 Duggar for his work in developing pure culture spawns 

 which have placed the whole proposition on a more cer- 

 tain, scientific and satisfactory basis, thus making it com- 

 parable to other lines of horticultural production. 



The making of pure culture spawn is in itself a special 

 enterprise requiring skill and laboratory equipment, and 



