26 Principles of Plant Culture. 



perature at which they can germinate. The following 

 table* shows approximately the minimum, optimum and 

 maximum temperatures at which seeds of the species 

 named germinate. 



MINIMUM. OPTIMUM. MAXIMUM. 



Barley 41 F 77-88F 99-lllF. 



Bean (Scarlet runner) 41 77-88 88-99 



Buckwheat 41 93 115 



Clover (red) 88-99 99 -111 Ill -122 



Cucumber 60-65 ..'....88-99 111-122 



Flax 41 77-88 88-99 



Hemp 32-41 99-111 111-122 



Indian Corn .................... 41-51 



Lucern (Alfalfa) ............. 88-99 



Melon ............................. 60-65 



Oat ................................ 32-41 



Pea ................................. 32-41 



Pumpkin ........................ 51-60 



Rye ................................. 32-41 



Sunflower ....................... 41-51 



Wheat ............................ 32-41 



....99 -111 Ill -122 



....99 -111 Ill -122 



....88 -99 Ill -122 



....77 -88 88 -99 



....77 -88 88 -99 



....93 -111 Ill -122 



....77 -88 88 -99 



....88 -99 99 -111 



....77 -88 .. 88 -108 



These temperatures refer to the soil or other medium 

 with which the seeds are in contact, and not to the 

 atmosphere. 



When moisture is sufficient, the time from planting to 

 sprouting decreases rapidly as we approach the opti- 

 mum temperature. In an experiment, Indian corn 

 sprouted in one-third of the time at 88 F. that it re- 

 quired to sprout at 61. 



Seeds of tropical plants usually require higher tem- 

 peratures for germination than those of temperate 

 plants. 



t\..*^3i. Free Oxygen is Essential to Germination. If 

 ! we place in the bottom of each of two saucersf a layer 



* Compiled from Haberlandt and Sachs. 



t If flower-pot saucers are used they should first be well soaked 

 }n water, so that they will not extract water from the soil. 



