178 THE PRINCIPLES OF FLORICULTURE 



pecially true if one is to specialize in carnations, or if 

 many chrysanthemums, roses or bedding plants are to be 

 propagated by cuttings. Upon the ease with which sand 

 may be aerated and its capacity to retain moisture, depends 

 in a large measure the success of propagation. If sand of 

 large particles be used, water drains from it quickly, and 

 the amount of air which is admitted dries the tissue of 

 the cutting before rooting takes place. On the other hand, 

 if the sand is too fine, it retains moisture and excludes air 

 to such an extent that healthy root action cannot begin. 



The sand should be free from all forms of humus, other- 

 wise the cutting bench fungus, known as " damping- 

 off " fungus, will be prevalent and many cuttings will be 

 lost. 



As a rule, plants under glass grow best if the soil con- 

 tains a mixture of medium sand, silt and clay. The pro- 

 portions vary with different crops, and the plant require- 

 ments have to be studied carefully. They are learned 

 largely by investigation and experimentation. Experi- 

 ment stations in connection with the agricultural colleges 

 and the United States Department of Agriculture have 

 done much valuable work in determining correct soil 

 conditions for various species of plants, but much remains 

 to be learned. 



144. Soil for violets. In his book on violet culture, 

 Galloway ! discusses the matter of soils for violets as fol- 

 lows : " By varying the texture of the soil, its water content 

 is varied, its capacity for heat is modified, and so on until 

 every important factor, including food in the ordinary 

 acceptance of the word, is involved. To these variations 

 the plant adapts itself, and the results may be extensive 

 leaf-development with few or no flowers, or vice versa, a 

 1 " Violet Culture " by B. T. Galloway. 



