68 MANAGEMENT OF THE FORCING-HOUSE. 



dull spells of midwinter. In such weather, plants tend 

 to grow soft and succulent, a tendency which is aided 

 by over-watering. If there is a sudden rise in tempera- 

 ture and a spell of bright weather, such flabby plants are 

 likely to flag, scorch, curl, or otherwise suffer. It is, there- 

 fore, extremely important that the gardener should aim to 

 keep his plants "hard" in these cloudy days. 



In cold weather, the chill should always be taken off 

 the water before it is applied to soil in which "warm" 

 plants like cucumbers, melons, tomatoes and egg-plants 

 are growing ; and it should also be done with lettuce if 

 the hose water is colder than 60. There are devices (of 

 which the so-called Kinney pump is a good example) for 

 drawing hot water from a tank or pail into the hose in 

 just the right proportion to temper the water ; or, if the 

 establishment is not too large, a watering-pot may be 

 used. In large establishments, where steam power is 

 used, an arrangement can be perfected for ejecting steam 

 into the water. Rain water is undoubtedly the best water 

 for plants, but ordinary spring or reservoir water is not 

 injurious, and is generally used. 



WATERING BY SUB-IRRIGATION. 



Recent experiments have shown that water may be 

 economically and efficiently applied to forced plants by 

 means of pipes laid in the bottom of the bench. The 

 writer's attention was first called to this line of investi- 

 gation in 1890, when certain studies were proposed to 

 determine what relation the supply of soil water has 

 to the transpiration of water from the foliage and to the 

 consequent rate of growth of the plant. Experiments 

 were begun at Cornell in 1891, but facilities were not at 

 hand to continue them. In this same year, Mr. W. J. 

 Green published preliminary results of somewhat similar 

 and more important experiments at the Ohio Experiment 

 Station, and his investigations were begun in 1890, in 



