CHAPTER XIII 
CONSTRUCTION OF GREENHOUSES 
171. Extent used. — Greenhouses are in far more gen- 
eral use among' market gardeners than they were 10 or 
15 years ago. They have become especially numerous 
near railroad lines affording satisfactory shipping facili- 
ties and large cities providing good markets for forced 
vegetables. When a grower learns that a greenhouse 
is a profitable investment the usual tendency is gradually 
to increase the area of glass, as many examples of such 
expansions will prove. The first house is perhaps very 
small and built for the purpose of starting early vege- 
table plants, for which it is found convenient and satis- 
factory; but the owner is often unwilling to have it idle 
more than half the year, and, therefore, he tries a forcing 
crop. If his efforts in the production of crops under glass 
prove successful, the greenhouse area is increased and 
new houses are built from year to year, until the grower 
is known as a vegetable forcer rather than a market 
gardener. The greenhouses furnish better conditions for 
starting early plants and they may be used 10 or 11 
months in the year if the establishment is properly 
handled. It is not uncommon for market gardeners to 
operate an acre or two of greenhouse space, while a much 
larger proportion of growers have from 1,000 to 10,000 
square feet of glass. 
172. Advantages. — If forced vegetables can be made 
profitable in connection with market gardening, there 
should be no hesitation in constructing greenhouses. 
They enable the grower to keep in touch with the market 
the year round, and they provide employment in the win- 
ter when it is often difficult to find sufficient work to 
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