38 BULLETIN 475, U. S. DEPARTMENT OF AGRICULTURE. 



New Mexico, northern California, Washington, Oregon, and Utah. 

 In southern California only, on account of the long, dry season so 

 closely following the spring planting season, planting in the fall 

 after the beginning of the rains is considered best. 



The time of year when seeding should be done varies with the 

 climate and, to a less degree, with the species. The important thing 

 is to vary the time of sowing with climatic conditions, so that the 

 seedlings will get the greatest possible supply of moisture. In gen- 

 eral, tree seed should be sown immediately preceding or at the begin- 

 ning of the characteristic period of precipitation in the region. 

 Exception to this rule may be necessary on account of peculiarities 

 of certain tree species or local abundance of rodents. 



FALL SOWING. 



Fall sowing is advantageous for species whose seed normally 

 germinate slowly, such as white pine, the true firs, Douglas fir from 

 the Pacific coast, western yellow-pine seed from Idaho or California, 

 and seed which deteriorate rapidly, such as incense cedar. In regions 

 where part of the precipitation comes in the form of snow and where 

 after its disappearance in the spring a hot, dry period of several 

 weeks or more follows, fall sowing is advisable. Fall-sown seed 

 germinate earlier in the spring than others, and the plants have a 

 better chance to establish themselves before the drought becomes 

 severe. Danger of destruction of seed by rodents is not so great, 

 because there is usually an abundance of natural foods during this 

 season, but subsequent depredations by rodents during the winter 

 may be very severe. In general, fall sowing is preferable on areas 

 which will be snow covered all winter. 



WINTER SOWING. 



Sowing on the snow in late winter and early spring has the same 

 effect of inducing early germination as fall sowing. Its chief 

 disadvantage is that broadcasting is the only feasible method. Fur- 

 ther, seed when first sown on snow are conspicuous and likely to be 

 eaten by birds, though after a day or two of sunshine they disappear. 

 They also sometimes slide along the surface of the snow, and, con- 

 sequently, can not be distributed evenly. 



SPRING SOWING. 



Spring sowing has the advantage of not exposing seed to premature 

 fall germination, to unfavorable winter weather conditions, or to de- 

 struction by birds and rodents for a period longer than is necessary. 



