THE FROST FACTOR. 151 



MOUNTAIN REGIONS. 



Sisson, Siskiyou 3555 July 6 Sept. 13 



Cedarville, Modoc 4675 June 24 Aug. 30 



Susanville, Lassen 4195 June 22 Sept. 8 



Laporte, Plumas 5000 July 6 Sept. 6 



Greenville, Plumas 3600 June 11 Aug. 20 



Boca, Nevada 5531 May 1 Oct. 2 



Summerdale, Mariposa 5270 June 15 Sept. 25 



Lick Observatory, Santa Clara 4209 May 25 Oct. 2 



Tehachapi, Kern 3964 Apr. 11 Nov. 20 



Cuyamaca, San Diego 4543 July 11 Sept. 5 



The general reader, after studying the foregoing data, 

 may conclude that in nearly all the valley districts of 

 California there is little difference in the length of the 

 absolute- frost-free period; also that elevation influences 

 temperature similarly in all parts of the State. At eleva- 

 tions below 1500 feet, which is the point at which foothills 

 begin to shade into mountains, there are about two-thirds 

 of the whole year in which even the tenderest vegetation 

 may be considered practically safe from injury from frost, 

 and particular situations in which the frost-free period 

 is even longer. On the other hand, there are mountain 

 valleys, with good soil and sunshine and ample total heat 

 for vegetables, in which tender plants must be always pro- 

 tected, because frost may occur every month in the year. 



The Endurance of Different Vegetables. The degree of 

 cold which plants will survive depends upon several con- 

 siderations and conditions, involving state of air, moisture 

 and of the plant itself, which makes it impossible to fix the 

 injury point of a plant definitely. There is. however, prac- 

 tical value in the following compilation made from reports 

 by Pacific Coast growers as to the effect of our style of 

 low temperatures, the temperatures being given as nearly 

 as possible those in contact with the plant itself : 



TEMPERATURE AT WHICH CERTAIN PLANTS ARE LIABLE TO RECEIVE 

 INJURY FROM FROSTS. 



Degrees Degrees 



Plant. Fahr. Plant. Fahr. 



Asparagus 29 Beans 31 



Cantaloupes 32 Celery 28 



Cucumbers 32 Onions 28 



Potatoes 30 Sweet Potatoes 31 



Spinach 21 Squash 31 



Turnips 26 Watermelons . . 31 



