276 



GARDEISERS' CHRONICLE 



Electric Light Speeds Up Plant Growth 



E. S. MACKAY 



I'lant.i Grown at 'l\cicc Tlicir Xnniial A'li/r zvilli iJic .lid of Six 



500-U'iitt Electric Lciml^s Turned on From 8 /'. ^1/. to 



1 A. M. During Six IVeeks' Test. 



IX a six-weeks test ju-~t completed 1(\- the Westiiii^house 

 Lamp Company, in co-operation with Peter 1 lender- 

 son & Company, at the Henderson proving grounds at 

 lialdwin. L. I., the value of electric light for accelerating 

 the growth of a variety of plants was conclusively proven. 

 Many of the specimens subjected to electric light grew 

 during the test upwards of twice the size of similar 

 plants receiving daylight only, and were considered liy 

 exjierts to he from fourteen to twenty-seven davs in ad- 

 vance of normal growth. Of the plants selected for 

 testing, flowers and vegetables having large leaf sur- 

 faces such as lettuce and endive, responded most readilv 

 to the stimulating effect of the light. The tests indicate 



that electric light will be useful to Horists and gardeners 

 in forcing flowers for definite dates such as Christmas 

 and Easter, and in reducing the time re(|uired for seed- 

 lings to grow large enough to permit transplanting. 



"No use of artificial light, in addition to that which in- 

 volves the eye, can be of greater benefit to humanity than 

 this recently developed application to stimulating the 

 growth and development of plants and vegetables." says 

 Samuel ( i. llibben. National Secretary of the Illuminating 

 l-".ngineering Society and Manager of the Illumination 

 r.ureau of the Westinghouse Company, under whose 

 direction these recent investigations have been conducted. 



"In a general way we have known that artificial light 

 influences the growth and flowering of certain plants, but 

 no well organized research work has been done until 

 recently to prove whether the application of electric 

 light was commercially feasible as a means of supple- 

 menting davlight. We now know that this stimulation of 

 growth does not necessarily require the same intensity of 

 light as daylight, nor does it seem necessary to reproduce 

 exactly the color qualities of daylight. We know further- 

 more that ]3lants must rest, and that the application of 

 artificial light is advi.sable over only carefully chosen hours 

 when daylight is inadequate. 



.IX Cyclamen. Mmli-iil and .iriiticial Light. 

 A-Y Cyclamen. Sunlight Only. 



■i-X Uypsophila /;7i\i;ini.v. .S'ioi/i.ii/i/ and .Irtilicial /.(.-/i^ 

 4-V Gy/'so/'hila Elegans. Sunlight Only. 



"What this development means to the agriculturist is 

 hard to predict. It seems, however, to jjromise a means of 

 doubling the speed of development of many sjiecies, and 

 bids fair to enable the horticulturist to bring his flowers 

 into bloom at the time when their market is at its best. 

 This has all been made jxj.ssible by the i)erfection of flex- 

 ible and cheap sources of light, and in it are contained 

 ad\;intages that seem as ti'emendous in their benefits to 

 humanity and as far reaching in their scci])e as anything 

 \yhich has ha])i)ened since Luther I'.nrliaiik developed the 

 .Shasta daisy or s])ineless cactus." 



< )n the first of .Sei)tember twelve varieties of vegetables 

 and twelve of flowers were sown in shallow (3 inch) 

 l)oxes, or flats, as gardeners term them. The soil u.sed 

 \\;i> an ordinary liglit sandy soil such as is generallv used 

 lor starting seedlings. Two sets of flats were sown, one 

 set for growing mider the electric liglit and one for grow- 

 ing without artificial light. 



The following varieties of seeds were selected for the 

 experiment : 



Smiwliall (auliflowiT Transvaal Daisy 



liasy lilaiK-hiiiR Celery Ora?iKc Calciuliila 



Tender (irecii I'.ean Bhu' I.ace Flower 



