SYSTEMS OF CROPPING 381 
chicory, for example. But the question of demand should 
be carefully considered before planting any crop. 
(2) Character of the houses. Low, poorly constructed 
houses would not do at all for winter cucumbers or to- 
matoes, while they might give at least fair results when 
planted with lettuce or radishes. 
(3) Character of the soil. This is not so much of a 
factor as might be supposed, unless one desires to grow 
head lettuce, when the soil should contain a large per- 
centage of sand. Any good agricultural soil may be 
made to yield profitable greenhouse crops, but the lighter 
types are preferred. 
(4) Ease with which the crop may be grown. Some 
crops are much more difficult to grow than others. It 
would be folly for an inexperienced grower to make any 
attempt to produce melons under glass. As experience is 
gained, the more difficult crops may be tried and, if 
desired, they may be grown at midwinter, when the 
greatest skill is required. 
(5) Labor supply. Some crops require more work 
than others. Winter cucumbers or tomatoes, for instance, 
require far more attention than lettuce. - ae 
(6) Personal preference. Farmers succeed best with 
the class of livestock which they like the best, and grow- 
ers of greenhouse vegetables obtain the best results from 
crops which appeal to them the most. 
Single cropping.—It is unnecessary to enter into a 
lengthy discussion here of the disadvantages of a one- 
crop system of farming, whether in the open or under 
glass. It is never economical in the utilization of the 
applied or natural sources of fertility, and fungous and 
insect pests are likely to be much more destructive than 
when a rotation of crops is followed. When one crop is 
grown from early fall until August 15 of the following 
year, advantage cannot be taken of differences in light 
and temperature due to seasonal changes. Not one of the 
