SEED AGE. I5 



they may be benefited by it. If the soil in seed beds should 

 become too cool, watering with warm or tepid water will be 

 found helpful. 



It is impossible to give rules for the determination of the proper 

 temperature for different kinds of seeds. In general, it may be 

 said that seeds germinate most rapidly at a temperature a few 

 degrees above that required for the best development of the 

 plant itself. Hardy plants require a temperature of from 50 

 to 70, conservatory plants from 60 to 75 or 80, and tropical 

 or stove plants from 75 to 95. The plantlets should be re- 

 moved from these highest temperatures, as a rule, as soon as 

 germination is completed, 



In out-door culture, depth of planting has a direct relation to 

 temperature. Seeds may be planted deeper late in the season 

 than early, when the soil is cold and damp. Deep planting 

 probably as often kills seeds because of the absence of suffi- 

 cient heat as from the lack of oxygen or the great depth of 

 earth through which the plantlet is unable to push. 



Preparatory Treatment of Seeds. Many seeds demand 

 some treatment preparatory to sowing. Nearly all hard and 

 bony seeds fail to germinate, or at least germinate very irregu- 

 larly, if their contents are allowed to become thoroughly dry 

 and hard. The shells must also be softened or broken in many 

 cases before the embryo can grow. Nature treats such seeds by 

 keeping them constantly moist under leaves or mold, and by 

 cracking them with frost. This suggests the practice known to 

 gardeners as stratification, an operation which consists in mixing 

 seeds with earth and exposing them to frost or to moisture for a 

 considerable time. 



Stratification is practiced, as a rule, with all nuts, the seeds of 

 forest trees, shrubs, the pips of haws and often of roses, and 

 in many cases with the seeds of common fruits. It should be per- 

 formed as soon as possible after the seeds are mature. Small 

 seeds are usually placed in thin layers in a box alternating with an 

 inch or two of sand. Sometimes the seeds are mixed indiscrimi- 

 nately in the sand, but unless they are large it is difficult to 

 separate them out at sowing time. The sand is often sown with 



