
14 
EFFECT OF LOW TEMPERATURES ON GREEN- 
HOUSE sri coNeis 
Having regard to the coal situation for the coming winter, a 
few notes concerning the experiences of the Brooklyn Botanic 
Garden during the winter of 1917-1918 may be of interest. 
About the middle of December it was considered to be ex- 
tremely doubtful if sufficient coal would be available to maintain 
the plant houses at a proper temperature for the rest of the cold 
season. It was immediately decided to conserve fuel by lower- 
ing the minimum temperature, normally maintained in all the 
greenhouses, ten degrees, the theory being that, although a num- 
ber of plants would undoubtedly suffer by such a course, that 
was preferable to losing the whole of the collections by a freeze up, 
occasioned by using all the fuel in maintaining ideal temperatures. 
All but the absolutely essential heat was shut off from the 
laboratory building. It was soon found that these measures 
would not result in saving enough coal to tide us over until further 
supplies could be secured. It was then decided to close off a 
number of houses (about half) entirely and remove their contents 
to the remaining houses. This of course resulted in much over- 
crowding, and probably caused almost as much damage as lowered 
temperatures. Three houses, containing plants that will with- 
stand cool conditions, from which it was not practicable to shut 
off the heat entirely, were maintained at a temperature just 
sufficient to keep the pipes from freezing. One of these houses, 
the Cactus and Succulent house, received the whole of its heat 
from the workroom below through the elevator shaft, which was 
left continuously open. 
ae following notes will give an idea of the effect of low 
temperatures on some of the plants. 
Cactus House-—Minimum winter temperatures maintained 
under normal conditions, 45°—50°. Lowest temperature recorded, 
30°. Temperatures of 32° recorded three times, 30° twice. The 
temperature fell below 40° on 25 occasions. 
Very little damage was done in this house. The leaves of 
several species of Pereskia were shrivelled, but the plants other- 
