THE HORTICULTURAL SOCIETY OF NEW YORK 



ination the plants have grown and brought fruit in a little more 

 than half the time required under the daylight alone, in other 

 words, the artificial light causes about double the rapidity of 

 growth and development. 



"After harvesting about three quarts of string beans, or about 

 90 cents worth, an estimate of the power rate of 54 cents per kw- 

 hr. was made and the beans actually cost $167.00." 



It seems that this experiment was not carried on with its 

 economic worth kept in mind, and certainly in the light of past ex- 

 periments there were too many lamps used on such a limited space 

 and without consideration of the economic expenditure. Never- 

 theless the same report gives out the following: 



"Assume, for instance, that the plants are in 6-in. pots. By 

 proper arrangement one 500-watt lamp could illuminate a circle 

 6 ft. in diameter, thus accommodating 144 pots. Intense illumin- 

 ation for one week or seven days, 18 hours per day, would acceler- 

 ate the development by about five days and would require 63 kw- 

 hr. At 5 cents per kw-hr., this would cost $3.15 or a little over 2 

 cents per pot, an expense which would be fully warranted eco- 

 nomically if it makes the product salable at the high seasonal prices. 

 Probably a materially higher cost for correcting a retardation of 

 several weeks would be economical." 



According to the Yearbook of 1920, United States Department 

 of Agriculture, W. W. Garner and H. A. Allard carried on some 

 valuable experiments. They found in some instances that plants 

 were brought into flower and fruit by shortening the day at certain 

 seasons. The Biloxi and Peking Soy-beans were used. The com- 

 mon wild aster when exposed to 7 hours of light daily was in bloom 

 in 36 days, as against 122 days when exposed to light for the en- 

 tire day. Other plants such as Lima Beans from Pennsylvania, 

 ragweed. Chrysanthemums and others responded in a similar way 

 to the soy-beans. 



On the other hand, experiments show that some plants such as 

 those that flower in the late spring and early summer do not re- 

 quire short days to reach the flowering stage. Among this group 

 of plants are the winter annuals and many of our common vege- 

 tables. 



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