EXTERNAL REQUIREMENTS 



219 



Moisture. Moisture is essential to prevent wilting 

 and to promote root development. It is furnished to the 

 plant by means of frequent waterings and maintained by 

 shading to reduce transpiration. With plants having a 

 large leaf surface, it is especially important that the air 

 be kept in a moist condition. 



Various devices are used for confining the air about 

 cuttings to prevent excessive evaporation. A bell jar is 

 probably the simplest 

 method. A very prac- ^J| 



tical device for the home 

 consists of a box covered 

 with a pane of glass. 

 In greenhouse work, the 

 cutting bench is covered 

 with sash when the re- 

 quired moisture cannot 

 be easily maintained by 

 other means. Gener- 

 ally, however, frequent 

 watering and shading by 

 means of whitewashing 

 the glass of the green- 

 house or by placing lath 

 screens above is suffi- 

 cient to prevent exces- 

 sive transpiration. 



Soil. The medium in which the cutting is placed for 

 rooting is as important as the temperature and moisture con- 

 ditions. Some plants may be rooted by placing the cuttings 

 in water. Others may be rooted by placing them in moist 

 sphagnum moss ; but as a rule, soil is most satisfactory. 



Pig. 119. Plant growing under a bell jar 

 to prevent excessive evaporation. 



