8 VEGETABLE FORCING 
handicapped by transportation charges and other diffi- 
culties. In order to meet the competition of both classes 
it is necessary to use every possible means to maintain a 
low cost of production. Greenhouse growers have suc- 
ceeded remarkably well in this respect, and nothing has 
contributed so much to the advancement and extension of 
the industry. : 
Various factors enter into this problem, the following 
being the most important: (1) Durable and substantial 
greenhouses of semi-iron frame construction at moderate 
cost. (2) The elimination of benches, concrete beds or 
other fixtures, which increase the cost of construction and 
maintenance, interfere with tillage, handling of manures 
and the general management of the house. (3) Improved 
systems of heating and ventilating. (4) Overhead water- 
ing, which reduces the cost of labor for this operation to 
a minimum. (5) Better facilities for harvesting and 
marketing greenhouse crops. (6) Larger greenhouses. 
The cost of growing 100 pounds of lettuce in a house 
covering one-tenth of an acre is necessarily greater than 
in an acre or a five-acre range. (7) Soil sterilization and 
better sanitation have made possible the use of the same 
soil indefinitely, the heavy expense of making frequent 
changes of the soil being thus eliminated. (8) Improved 
varieties adapted to greenhouse culture have done much 
for the industry. (9) Proximity to market, railroad, and 
supplies of manure and coal. (10) A trained and regular 
force of employees. 
Capital required—The capital required to engage in the 
vegetable-forcing industry depends upon conditions 
which are so variable that it is difficult to give estimates 
of definite value. The cost of a good semi-iron form of 
greenhouse construction for an acre is approximately 
$20,000, although such houses have been constructed for 
several thousand dollars less than that sum; two acres of 
land in the suburbs of a good market would probably cost 
