368 GREENHOUSE MANAGEMENT. 



mer, the plants should be examined two or three times 

 and should receive water, if .they show the need of it. 

 While cistern water can be used, for most plants, it is 

 desirable that the chill be taken from water brought 

 directly from springs. For stove plants and others 

 requiring a moderately high temperature, it will be 

 necessary to provide some- method for warming the 

 water. This can generally be done by providing tanks 

 through which steam or water pipes can pass. 



SUB-IRRIGATION. 



For several years, experiments have been carried on 

 in watering plants growing in greenhouse beds, through 

 subterranean pipes. In nearly every case good results 

 have been obtained, as there was not only a larger and 

 earlier development of the plants, but the labor of appli- 

 cation was greatly reduced, and a smaller amount of 

 water sufficed. In many cases, too, the danger from 

 attack of various plant diseases was lessened. Among 

 those who have had most experience with sub-irrigation 

 in the greenhouse is Professor W. J. Green, of the Ohio 

 Experiment Station, who has prepared the follow- 

 ing notes: 



SUB-IRRIGATION IN THE GREENHOUSE. 



Sub-irrigation in the greenhouse grew out of the 

 necessity of devising ways and means to prevent the let- 

 tuce rot. After several conversations on the subject, 

 between Mr. W. J. Green, horticulturist of the Ohio 

 Experiment Station, and Mr. W. S. Turner, assistant, 

 the latter set some lettuce plants in a box in which a 

 tile was so placed as to admit of watering without wet- 

 ting the foliage. The subsequent development of the 

 method is due to the combined efforts of W. J. Green, 

 E. C. Green and W. S. Turner. 



The experiments were begun in the winter of 

 1890-91, but in addition to some box trials a bed seven 



