JACK FROST NOT SO BAD AS HE IS PAINTED 



UPSETTING cherished popular notions is inevitable 

 as truth becomes uncovered, although to be sure 

 many beliefs in "what isn't so" die hard — they 

 have the vigor of age! The latest exploded theory 

 has to do with the effect of cold upon plant life. It 

 has been accepted that frost is the arch enemy of the garden 

 and that but for the winter cold we would have flowers, and 

 fruits, and verdant vegetation all the year round. Now the 

 scientists tell us that Jack Frost is, in the main, a beneficent old 

 fellow. It is admitted that if he comes too early, or stays too 

 late, his visit is likely to prove embarrassing. Yet if he did 

 not come at all — which means if we did not have any cold 

 weather — the majority of plants in the temperate zone would 

 show little, if any, growth in the spring. It is hard to believe 

 that the effect of cold is to stimulate rather than to retard plant 

 growth, but that is what actually happens so we are now in- 

 formed. 



One fact standing out clearly in the recent experiments of 

 Dr. Colville of the Dept. of Agriculture is that the dormant 

 condition of certain plants in winter is not the result of cold 

 and freezing; on the other hand, cold stimulates the revival of 

 life in the plant when spring comes. Such conception of the 

 effect of cold is new to the everyday reader, who is used to 

 looking upon winter temperatures as forcing the shrub into a 

 dormant state scarcely better than death. But healthy, husky 

 Blueberries which were in a government greenhouse "went to 

 sleep " just the same, despite the fact that the air was kept at a 

 growing temperature. 



The shrubs, it is true, did not go to bed so early as when Jack 

 Frost used to hurry them off, but go to sleep they did. Their 

 leaves dropped off, and in the warm greenhouse the plants went 

 into a dormant condition exactly like that of others outside in 

 the cold and snow. Moreover, they were late in waking when 

 spring came. Some, indeed, slept through the whole year. The 

 inference is that the plant's period of dormancy is a seasonal 

 matter not induced by the cold, but that the early and luxu- 

 riant growth cannot occur unless the plant has been through a 

 period of chill temperature. 



TWO interesting experiments were conducted with Blue- 

 berry plants. In the middle of February, a Blueberry 

 which had shed its leaves and become dormant in a warm green- 

 house, maintained at a temperature of 70 degrees, was repotted 

 and set in the south end of the greenhouse. A small opening 

 was made in the glass, through which one of the two stems of 

 the plant was thrust, the open space about the stem where it 

 passed through the glass being carefully plugged. During the 

 rest of the winter the plant was kept in the same position, the 

 pot and one stem remaining inside in the warmth, while the 

 other stem, projecting through the glass, was exposed to the 



rigors of winter outside. About the middle of April the out- 

 door branch (which had been frozen) started into normal 

 growth, while the indoor branch (kept continuously warm) 

 continued dormant. 



Another plant was set on a shelf outside the greenhouse and a 

 single branch run through the glass into the warm interior. 

 When spring came the interior branch remained dormant, all 

 the outside branches leafing promptly. Evidently the causes 

 that stimulated growth in the exposed stems operated in the 

 stem itself, not in the roots. The theory is that cold weakens 

 the plant cells, and by partial destruction turns the starch to 

 sugar. 



The importance of this chilling to those trees and shrubs 

 which are subjected each year to several months of freezing 

 weather becomes obvious. If so constituted as to start into 

 growth as easily in the warm days of late fall as in those of early 

 spring, many species would come into flower and leaf in the 

 mild autumn spells of " Indian summer," and the stored food 

 required for the plant's normal vigorous growth in the following 

 spring would be wasted in a burst of new autumn growth, to be 

 killed by the first heavy freezes. But when two or three 

 months of chilling are necessary before a newly dormant plant 

 will respond to the usual effect of warmth, such plants are pro- 

 tected against the dangers of growth in " Indian summer." It 

 is probable that all our native trees and shrubs are thus pro- 

 tected. 



A SIMPLE and instructive experiment may be made in the 

 fall and winter with such early spring-blooming plants as 

 Alder, Hazelnut, Pussy-willow, Jasmine, Forsythia, Japanese 

 Quince, Peach, Plum, etc. Brought into the living room and 

 set in water in mid-autumn freshly cut, dormant leafless branches 

 of these plants will not bloom ; but branches cut at later dates will 

 respond and flower though not, however, until the expiration 

 of the chilling period appropriate to each kind. 



In the tropics where there is no chilling weather, such as 

 we know it here, trees and shrubs spring into growth after the 

 dormant period of the dry season just as they do in temper- 

 ate climes after the dormant period of winter. There are 

 agencies other than chilling which will start dormant trees and 

 shrubs into growth even in our own latitude. 



Pruning a long dormant plant will often start it into 

 growth. Girdling produces a similar result. Notching the 

 stem does the same. Rubbing the stem may also start the plant 

 into growth. In all these examples of the stimulation of 

 growth by injury it is conceived that the enzym, or soluble 

 ferment which is found in all plants and which transforms starch 

 into sugar, is brought into contact with the starch as a direct 

 result of the breaking and straining of the cells, thus causing 

 sugar to be formed and growth to begin. Tropical plants 

 probably have various methods of coming out of their 

 dormancy, and there is every reason to expect that some 



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