48 HORTICULTURE FOR SCHOOLS 



of many tropical plants germinate at 100 degrees F., while 

 those of some maples germinate just above the freezing point. 

 Seeds with thick hard shells generally require higher tem- 

 peratures than those with thin coats. 



65. Media for germination. Seeds will germinate in any 

 material in which sufficient amounts of heat, moisture, and 

 oxygen can be maintained, provided there are no injurious 

 (toxic) substances present. In nature the soil is the medium 

 for germination. 



For study, seeds can be germinated in boxes of soil or sand 

 in a room where the proper temperature is maintained, or 

 outdoors if the time of year and climate permit. Sawdust 

 (not oak or redwood sawdust) is a clean and convenient 

 medium in which to grow seeds for study purposes. The 

 sawdust can be placed in small boxes or flats and should 

 be kept moderately moist (not wet) and at the correct 

 temperature. 



Seeds may be germinated by rolling them up in sheets of 

 blotting paper, or newspaper. The roll can be tied with a 

 string or rubber band and should then be dampened and 

 stood on end in a jar containing a little water. The water 

 rises in the roll and keeps the seed moist. By placing the 

 seeds in rows across the roll, a large number of samples can 

 be tested at the same time. 



Another kind of germinator can be made by placing sheets 

 of blotting paper in a platter, placing the seeds between the 

 moist blotting papers, and covering with a similar dish to 

 retain the moisture. 



Small seeds may be germinated by placing them on moist 

 blotters in a saucer, and covering them with an inverted " 

 tumbler. When thus placed, they may be examined at any 

 time without being disturbed. 



Germination tests are useful in determining the value of 

 seeds for planting purposes. If they do not sprout within the 

 proper time, they are without vitality and are quite worthless. 



