90 PACIFIC STATES FLORAL CONGRESS. 



may be made either of light materials, canvas, muslin, light wood- 

 work, or artificial screens may be made of smoke given off damp straw, 

 old wood, primings, manure, etc., burning briskly and occasionally 

 doused with water. All of these screening methods have the advantage 

 of serving as a barrier between the chilled fruit and the sun's rays at 

 the time of sunrise, and therefore also come under the second class of 

 protective methods. 



It seems to me that we shall find in practise that a generous use of 

 water will be highly efficient in both truck and flower gardens. The 

 air is warmed, strange as it may seem, by this generous use of water. 

 As was pointed out before, much water means that the water vapor of 

 High saturation will be condensed as the temperature falls, and a large 

 amount of heat is given off in this process of condensation. It requires 

 heat to boil water, in other words, to cause evaporation, and conversely 

 just as much heat must be given out in the reverse process of condens- 

 ing the vapor. The ground mists which can be so often seen on cold, 

 clear nights as the temperature falls illustrate nicely this process of 

 nature for checking a too rapid fall in temperature. Indeed, the water 

 vapor plays a part somewhat similar to that of the governor in the 

 engine-room. Where there is little or no water vapor, the fall in tem- 

 perature is extremely rapid. Where there is much water vapor, the 

 <:urve showing the fall in temperature is never very steep. Do not for- 

 get, therefore, that the water vapor, even if it does turn into a heavy 

 frost by morning, is, nevertheless, a friend, 'and prevents, by its very 

 act of solidification, too sharp a drop in temperature. It may seem 

 like an anomaly, but in some respects the heavier this deposition of 

 frost, the better are the chances of the flower or vegetable escaping 

 serious injury. 



Gardens should be irrigated, and at nights when frosts are antici- 

 pated, water should be turned on in the ditches. In large gardens a 

 very efficient way, though somewhat expensive, is to use water that has 

 been partially warmed, having a temperature say of from 60 to 80 



I have no hesitation in saying that I believe a combination of wire 

 baskets and running water will carry any vegetable or flower garden 

 through such frost periods as we are apt to have in this state. Indeed, 

 I think protection may be effective with the temperature as low as 

 20 or 22 degrees. 



"Under the second class of protective methods we are called upon to 

 c-arry the chilled flower or vegetable from its "dormant and possibly sap- 

 injured condition back to normal temperatures without further injury 

 of the cell sap. For this purpose it is essential that the warming up 

 must be gradual. There must be no rapid thawing out at a time when 



