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. 
