120 CALIFORNIA VEGETABLES 



hours may frequently reach the freezing point, but its continuance 

 may not be for a length of time sufficient to injure the plant 

 structure; in fact, owing to the dryness of the air, frost does not 

 always form with a temperature of 32 degrees or even several 

 degrees lower, and in addition plant life subjected to such variations 

 in temperature becomes more hardy and lower temperatures are 

 required to cause serious injury. On the other hand, in the more 

 humid regions the radiation at night is less rapid, the nights as a 

 rule are not so markedly cold, plant life is less hardy, frost forms 

 readily at the freezing point, the same degree of cold is often pro- 

 tracted over much longer periods of time, and vegetation is there- 

 fore more seriously affected." * 



SUCCESSIONS AND ROTATIONS IN CALIFORNIA GARDENS. 



Naturally, an all-the-year growing season suggests constant 

 use of the ground and the possibility of turning the soil over several 

 times in the course of the year. This can be done by quick revolu- 

 tion, like the following : 



Where water is handy two, three, or even four crops can be grown on 

 the same ground in the year. Start April 1 and sow the plot to lettuce, and 

 with proper cultivation it will mature in two months. Resow with turnip- 

 radish, which is a good summer variety. These will be fit to use in three 

 weeks, or by the first week of July, when the ground will be ready for late 

 cucumbers which will occupy the ground until the first frost, or till the 

 nights become too cold for them to fruit. Now plant to carrots, beets, or 

 onion sets, and any of them will be ready for use in February or March. 

 Here we have four crops within the twelve months, and no two of them 

 occupying the ground at the same time. There are other combinations that 

 would do as well. 



Though this rapid work is quite feasible, as shown, and many 

 plants can enter into such combinations, the two crop plan will 

 probably be as fast movement as most farm gardeners will keep 

 up with, and that consists in fall sowing of hardy vegetables for 

 winter and spring use, followed by spring planting of tender vege- 

 tables for summer and fall use. Occasionally there will be intervals 

 in this rotation for a third or catch crop of lettuce, radish, etc., which 

 takes a very short time. This will be a vast improvement on the 

 present popular conception of gardening possibilities, and if the 



*Frost Data of the United States Bulletin V, U. S. Weather Bureau, 1911. 



