DEPTH OF PLANTING 75 



seeds must be planted, the more difficult and uncertain is this 

 method of attempting to secure moisture for the germination of 

 seeds. The much more certain way of securing germination is to 

 plant only when the seeds can be planted in direct contact with 

 moist soil. 



In the carefully prepared soil used in a greenhouse or a hotbed 

 and with the facilities for artificial watering, there is no difficulty 

 in maintaining an abundant supply of moisture in contact with 

 any seeds that may be sown under these conditions. 



Relation of Drainage to Germination. — Since seeds will not 

 germinate without the presence of oxygen, it is essential that 

 provision be made for the rapid draining away of any surplus 

 water that may fall as rain or be applied artificially; for if the soil 

 becomes completely saturated with water and remains in that 

 condition, there will be no room for air, and hence no oxygen 

 available to the germinating seeds. Soils that are naturally well 

 drained or artificially drained present conditions more favorable 

 to the germination of seeds than do poorly drained soils. In the 

 greenhouse, seed flats and flower pots have holes in the bottom 

 to facilitate drainage. 



Different seeds germinate best at different temperatures, but 

 in general most seeds germinate well at a temperature closely 

 corresponding to that at which the plants thrive after they have 

 become established. Thus, seeds of the cool season crops will 

 germinate at a much lower temperature than those of the warm 

 season crops. Seeds of the warm season crops, if planted in moist 

 soil when the temperature is low, are likely to rot instead of 

 sprouting. Some of the cool season crops will germinate readily 

 at a temperature of 50° to 60° F., while a temperature of 70° to 

 80° is required for rapid germination of the warm season crops. 



In outdoor culture, the proper temperature for the germination 

 of the seeds is secured by regulating the time of planting the various 

 crops to meet their respective demands. Under glass, the tem- 

 perature is regulated by the amount of piping in the greenhouse, 

 the extent of firing in a flue-heated hotbed, and the amount and 

 quality of manure used in making a manure hotbed. 



DEPTH OF PLANTING 



Seeds should be planted deep enough to be well supplied with 

 moisture, yet shallow enough for the seedlings to be able to push 

 their way to the surface. Three factors chiefly determine the 



