24 BULLETIN 579, U. S. DEPARTMENT OF AGRICULTURE. 
perature of the celery in the center usually is several degrees higher 
than the temperature of the air. In the standard crate, 22 inches 
wide, the center of the celery is 11 inches from an air space, while 
in a crate 14 inches wide the center of the celery is only 7 inches 
from an air space. 
The cold air being heavier than the warm air it naturally falls to 
the low levels and the warm air rises. An artificial system of circula- 
tion tends to equalize the temperature and prevents the formation of 
cold-air pockets. In most storage houses, the aim is to maintain a 
temperature of about 32° F. ; but as the thermometers are usually 
placed a few feet from the floor they do not record the temperature 
near the top of the room, near the floor, or in the corners. Often 
when the thermometers register 32° F. the actual temperature at the 
height of the top tier of crates is 35° or 36° F., and near the floor and 
in the corners of the room the temperature is 2 or 3 degrees below the 
freezing point. The aim of the manager of the storage house should 
be to equalize the temperature and keep it as low as possible without 
allowing the celery to freeze severely. Slight freezing does no dam- 
age if the temperature is not raised quickly above the freezing point. 
In most storage houses, a temperature which does not freeze the out- 
side stalks of celery in the lower tiers of crates is too high to maintain 
the celery in the top tiers in a satisfactory condition. 
It is suggested that thermometers be placed at different heights 
throughout the storage rooms, in the corners as well as in the center 
passageways. All of these thermometers should be tested, and when 
the temperature shows much variation in the different parts of the 
room the air should be set in motion. This can be done by using fans 
or blowers, or by opening doors on opposite sides of the room when 
the outside temperature is about the same as the temperature in the 
storage house. Some houses are equipped with suction fans which 
draw off the warmer air at the top of the room. Cold air is then 
forced in. 
SUMMARY. 
Celery is one of the important truck crops grown in the United 
States, having a farm value in 1909 of $3,922,848. 
Six States — New York, Michigan, Massachusetts, Ohio, Pennsyl- 
vania, and New Jersey — produce about two-thirds of the celery crop, 
and a considerable portion of this is stored for a period of one to 
three months. 
The old method of storing celery in the field and in houses of the 
cellar and semicellar type is not satisfactory, because temperature and 
moisture conditions can not be controlled. 
