WATERING FORCING-HOUSES. 65 



WATERING. 



Of all the operations which fall to the lot of the gar- 

 dener, there is perhaps none which requires the exer- 

 cise of so much judgment as the watering of plants grow- 

 ing under glass. The frequency of the watering, the 

 amounts to apply, and how to apply it, must all be de- 

 termined by the immediate conditions. There can be no 

 rules for the practice. The best single statement to 

 make, perhaps, is to say that plants should be watered 

 when they need it ; but this means little. Plants may 

 need water and yet be ruined by the giving of it. 

 Watering is performed primarily to supply the plant with 

 food, yet there are certain secondary effects of the 

 practice which should be thoroughly understood. 



It must first be said that the application of water radi- 

 cally changes, for the time being, both the temperature 

 and physical condition of the soil, and these features are 

 the very ones which bear most intimate relations to 

 plant growth. Watering modifies the temperature of the 

 soil, both because the water itself absorbs heat and be- 

 cause the evaporation of it is a cooling process. Plants 

 which love a high temperature receive a serious check the 

 moment the soil is drenched with cold water. The 

 grower of winter melons, for example, must never hope 

 for the best success if he soaks his benches with hydrant 

 water. As a rule, water must be given at such times that 

 it will change the temperature of the soil the least and 

 will allow the quickest return to its normal warmth. In 

 the middle of the day, the change produced by watering 

 may be too violent. Water is then supplied indirectly by 

 wetting down the walks ; and when the temperature of 

 the air has been somewhat reduced the plants may be 

 syringed and the soil may be watered, if it needs. It is 

 generally better to water forced vegetables early in the 

 day in order that the soil may become thoroughly warmed 

 up again before night. Watering towards night is likely 



