136 Principles of Plant Culture. 



ature never falls to the freezing point. But in local- 

 ities subject to frost, the liability of damage to vegeta- 

 tion from this cause is goverened more by cold air 

 drainage (209) and proximity to water than by latitude. 

 It is as important to select locations for peach growing 

 with reference to spring frosts in the Carolinas as in 

 the peach belt of Michigan, and favorable locations for 

 the apple in Wisconsin sometimes escape damage from 

 spring frosts in seasons when the apple crop is cut off 

 by frost from extensive regions of the southern states. 



216. Methods of Preventing Injury by Frost. Any 

 non-conducting material lying between the earth and 

 space, whether spread directly upon the earth or at a 

 considerable height above it, acts as a blanket to inter- 

 cept the radiating heat, and thus prevents in a measure 

 the coding of objects beneath it. For this reason, 

 straw, muslin or other non-conducting material spread 

 over plants, usually protects them from frost. 



While it is easy to protect a few plants from frost 

 by covering them directly, it is much more difficult to 

 protect large plantations in this manner. Considerable 

 plantings of the strawberry have been successfully pro- 

 tected from frost by covering the rows in the evening 

 with straw or marsh hay, and where these materials 

 are convenient, the work may often be cheaply and 

 quickly performed. 



Attempts to prevent frost on a large scale by the 

 heat of fires or by burning material that produces much 

 smoke or vapor, have not been sufficiently successful to 

 commend these methods for general application. 



