78 MANAGEMENT OF THE FORCING-HOUSE. 



time in watering was as follows : In the case of under- 

 surface irrigation, the water was dipped out of a tank and 

 poured into a funnel, through which it entered the various 

 portions of the bed. On the other hand, in surface irriga- 

 tion, the water was dipped out and applied by a sprinkling 

 can, containing either a rose spray or a spout long enough 

 to reach all sections of the bed. In the former case, the size 

 of the plants did not matter, while in the latter, the more 

 mature the crop, the more time it required for watering. 

 Again, the sub-irrigated beds did not require watering over 

 once or, at the outside, twice a week ; while, generally 

 speaking, the other beds were watered daily. 



"The idea that a water-tight bed is detrimental to plant 

 growth on account of lack of drainage is overcome, we be- 

 lieve, in the fact that the pipe or tiles receive the excess of 

 water, which, in a bed not water-tight, would leak out at the 

 bottom, thus making it serve a double purpose. If the soil 

 contains too much moisture, it serves as a reservoir ; if not 

 enough, it imparts the amount necessary for good condi- 

 tions. In either case, the pipe or tiles act as a safety-valve. 

 These openings underneath the soil allow free access of air, 

 render plant food digestible, and act as a drain to water- 

 soaked soil. In view of these results, we feel safe in saying 

 that under-surface watering is a pronounced success." 



VENTILATING AND SHADING. 



The one imperative thing to be borne in mind in ventila- 

 ting glass houses is to avoid draughts. This means that 

 ventilators should be many and small rather than few and 

 large, for thereby the warm air can be discharged from 

 houses without much danger of an in-rush of cold air, 

 because the ventilator sash need be lifted only very little. 

 Houses should be cooled by letting out heated air rather 

 than by letting in cold air, although it is impossible to 

 wholly exclude the outside air when ventilators are opened. 

 In forcing-houses of ordinary size, sufficient ventilation can 



