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 arule, 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 
