160 Gardening 



The eight lines drawn mark off into zones that part of 

 the United States east of the Rocky Mountains. In 

 each of these zones the range of planting dates in spring 

 averages about the same. The earliest dates for plant- 

 ing the various vegetables in these zones are given in the 

 table on pages 348 and 349. There are, of course, local 

 conditions, such as elevation, drainage, and the slope 

 of the land, not indicated on a map of this kind, which 

 change somewhat the planting dates as given. Each 

 gardener must find out for himself the more exact 

 planting dates for his own locality and his own gar- 

 den. 



The western part of the United States is broken by 

 mountains and streams, which cause so much irregularity 

 in the frost dates that it is not possible to mark out this 

 area into definite planting zones. 



The killing frosts of autumn. The first severe frost 

 in autumn kills most garden plants. Tomatoes, corn, 

 beans, peppers, and eggplants are killed or badly in- 

 jured ; beets, carrots, cabbages, lettuce, turnips, pe-tsai, 

 celery, endive, and kale are not severely injured and may 

 be left in the garden until just before the ground is frozen. 

 Parsnips and salsify can be left in the ground over winter, 

 but even these more hardy plants practically cease 

 growth with the coming of severe frosts. 



In planning for late or autumn crops, and especially 

 for the succession crops, the gardener should know (i) 

 how long a period is required by the particular crop to 

 mature, and (2) when the first killing frosts are to be 

 expected. This is especially important in the northern 

 states, where frosts come earliest. 



