116 CALIFORNIA VEGETABLES 



localities concerned. The table which we have compiled and ar- 

 ranged in our own way, according to districts, from data kindly 

 furnished by Prof. McAdie, should be studied with the following 

 points in view : 



First. The dates represent the first and last dates of killing 

 frosts in each place during a decade. In most cases probably the 

 dates are not in the same year. We wish to show the ''worst ever" 

 at each place. 



Second. Obviously, then, frosts at such dates are not to be 

 often expected, and planters may usually take the risk of planting 

 somewhat earlier and having tender plants mature somewhat later, 

 as will be discussed in the next chapter. At the same time large 

 plantings for a main or standard crop should be generally held back 

 for the local frost-free period which the dates in the tables supply 

 for each place. 



Third. Always remember, however, that there may be situa- 

 tions adjacent to the place where the record is made in which frost 

 "may be earlier or later, or both, according to the variations in local 

 topography, exposure, etc., as explained in the chapter on Climate. 

 There are also a few widely separated situations which may be 

 considered almost, if not quite, frostless. 



Fourth. The tables give the elevation in feet above sea level 

 in each case. This factor does influence frost occurrence in a large 

 way, but local frost phenomena are often determined by the relative 

 elevation of situations in the same vicinity and by other conditions 

 of topography affecting the movement of cold air and counter cur- 

 rents, perhaps, of warm air. 



Fifth. Thus it should appear that after all the writer can do 

 to help the reader determine what his planting practice should be 

 with reference to frost occurrence, it still remains with the latter 

 to do all that he can to understand his immediate spot of land 

 through the teaching of his own observation and experience. 



DATES OF SPRING AND FALL KILLING FROSTS AT PLACES NAMED. 



Latest Earliest 



Location and County Elevation Spring Autumn 



Upper Coast Region 



Crescent City, Del Norte 50 June 19 Sept. 30 



Eureka, Humboldt 64 May 1 Nov. 7 



Upper Mattole, Humboldt 244 Apr. 26 Oct. 20 



Ukiah, Mendocino 620 May 2 . Oct. 16 



