74 EXPERIMENTS IN BLUEBERRY CULTURE. 



(32) Plants of the swamp blueberry are' exceedingly hardy and pass the 

 winter in good condition outdoors when the soil is covered merely 

 with an oak-leaf mulch, but when not exposed to outdoor condi- 

 tions they do not begin their growth in spring in a normal manner. 



During the fall, winter, and early spring of 1908-9 a series of blue- 

 berry seedlings of 1907 was kept outdoors on a south window sill to 

 ascertain whether repeated freezing and thawing would kill them. 

 Most of the plants were in thin glass 3-inch pots, covered at the sides 

 with one thickness of gray blotting paper. One plant (to which 

 reference is again made on pp. 75 and 76) was in a 5-inch earthen 

 pot. None of the plants were mulched or covered in any way. They 

 were watered ^^'henever necessary to keep the soil from drying. In 

 cold weather the air circulated freely about the pots and the soil was 

 repeatedly frozen solid. On warm, sunny days the melting of the ice 

 took place rapidly. Hard freezing followed by quick thawing was 

 many times repeated, and the conditions of exposure were such that 

 the plants undoubtedly were subjected to a severer test for hardiness 

 than they would ever receive under cultural conditions. 



The plants passed the winter without losing any of their twigs. 

 The wood was plump and in excellent condition when spring came, 

 as was evidenced further by the remarkable uniformity with which 

 every dormant bud started to grow after the first few warm days. 



For the roots of some of the plants in glass pots, however, the 

 exposure was too severe. In some of the glass pots no root growth 

 followed the starting of the twigs, and the plants finally died. In 

 others the root growth at first was feeble and the plants lost some of 

 their newly started twigs by withering. Most of the plants, however, 

 including the one in the 5-inch earthen pot, made normal growth of 

 both twigs and roots, notwithstanding the extraordinarily severe 

 treatment to which they had been subjected. No difficulty is antici- 

 pated, therefore, in wintering blueberry plants successfully out of 

 doors under any ordinary cultural conditions. The seedlings of 1908 

 covered with oak leaves in their outdoor plunging bed of sand passed 

 the winter of 1909-10 in good condition. 



That blueberry plants must be subjected to some sort of exposure, 

 if they are to start satisfactorily in the spring, is indicated by the 

 behavior of certain seedlings of 1907 which were carried through the 

 winter of 1908-9 in a rose house, where the temperature at night was 

 about 60° F. and during the day about 10 degrees higher. These 

 plants, although subjected to most persistent coaxing, absolutely 

 refused to grow during the the five months from November to March, 

 although newly germinated seedlings grew luxuriantly under exactly 

 the same conditions. 



The comparison of these indoor plants with outdoor plants may 

 best be made by an examination of the buds shown in the accompany- 



193 



