SOILS FOR THE FORCING-HOUSE. 51 



twice in the meantime, make a most excellent foundation 

 for a greenhouse soil. A satisfactory mixture may be 

 made by using one-third of these rotted sods, one third of 

 mellow garden loam, and one-third of fine old horse ma- 

 nure which has not been leached. If the garden soil has 

 itself been well enriched with stable manures, it will not 

 be necessary to add so much in the mixture. If the 

 completed soil contains so much clay as to be sticky, the 

 addition of sand will correct it. Leaf mold (not leaves) 

 in limited quantity is a most excellent substitute for ma- 

 nure. Broken and pulverized peat may also be used. It 

 is always important that the materials used in the forcing- 

 house soil should be fine and well broken down by the 

 processes of decay. Fresh and undecomposed materials 

 give variable and unpredictable results : they are the 

 "raw" soils of gardeners. Heavy clays are to be avoided 

 in the making of forcing-house soils, particularly if one 

 desires to grow the heading lettuces. 



The forcing-house soil is mixed by shoveling the ingre- 

 dients from piles into a central common pile, a given num- 

 ber of shovelfuls from each, and then shoveling the mixture 

 over once or twice. It is a good practice to cover the 

 bottom of the bench especially for melons and cucum- 

 bers with inverted sods, and then to put on the pre- 

 pared soil. Many gardeners do not take this trouble of 

 mixing the soil, and it is not necessary if one is able to 

 find a natural soil to his liking ; but unless the right soil 

 is at hand, it is always safer to take this extra pains 

 rather than to rely upon an indifferent soil. One cannot 

 afford to take any unnecessary risks in the forcing of 

 vegetables. 



When the crops are grown on benches as those must 

 be which require bottom-heat it is necessary to change 

 the soil every year. This is because the soil loses texture 

 or fiber and becomes partially exhausted of available plant 

 food, and it is likely to contain the spores of fungi or the 

 eggs of insects. Houses in which the soil remains un- 

 5 FORC. 



