Injury from Cold During Growing Period. 129 



plants may be smothered in warm winter weather. For 

 taller plants, as the grape and raspberry, the soil is 

 usually the most convenient and satisfactory covering, 

 as a litter covering tends to attract mice, that often 

 injure woody stems. To assist in bending down the 

 stems, a little earth is usually removed at the base on 

 the side toward which they are to be bent. Shrubs too 

 large for bending down may be inclosed in straw or 

 similar material. 



202. A Northerly Exposure is generally Least Try- 

 ing to Plants in winter, because it is least subject to 

 fluctuations in temperature. The influence of the sun 

 is here less perceptible and snow remains longer than 

 upon other exposures. The summit of a hill is usually 

 less trying than a valley, because the cold air tends to 

 seek the lower places, especially in still weather (209). 



203. Wind-Breaks, i. e., plantings of trees intended 

 to break the force of prevailing winds, act beneficially 

 in lessening damage from cold, in so far as they prevent 

 snow from drifting off the soil and mitigate the effects 

 of drying winds (189c). 



B METHODS OF AVERTING INJURY FROM COLD DURING 

 THE GROWING PERIOD. 



204. Plants are much more susceptible to injury from 

 cold during their growth period than during their dor- 

 mant period (170). Comparatively few plants, how- 

 ever, are injured by cold at any season until the tem- 

 perature falls below the freezing point of water (32 F., 

 C.), or when so-called hoarfrost occurs. It is this 



