CHAPTER V 
SOIL PREPARATION 
Ideal conditions in the greenhouse must be created, for 
no soil in its natural state possesses all of the requisites 
for the successful production of forcing crops. The 
vegetable forcer should be able to grasp the particular 
problems relating to the preparation of the soil to be 
used. Hard and fast rules cannot be laid down, because 
conditions are extremely variable. Different soils 
demand different treatment. But whatever the soil, it 
must have the required physical properties and contain 
an abundance of available plant food. It must also be as 
free as possible from harmful insects and plant diseases. 
The greatest care should be exercised in the preparation 
of soils for forcing purposes. 
Changing soils.—In the early stages of the greenhouse 
business gardeners and writers on vegetable forcing 
considered it necessary to change the greenhouse soil 
every year or two. Renewal was regarded necessary in 
order to provide a soil which possessed the correct 
physical and chemical properties. It was found, too, that 
insect pests and plant diseases became troublesome 
unless the soil was changed quite frequently. The 
custom is a good one for small greenhouses and private 
places where it is not practicable to employ modern 
methods of soil preparation. There are hundreds of 
private and small commercial houses where steam is not 
available for sterilizing the soil. Under such circum- 
stances it may be best to renew the soil quite frequently. 
On the other hand, it is highly probable that summer 
mulching with manure and sterilizing with formalin 
would be just as satisfactory in most instances as chang- 
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