HISTORY AND EVOLUTION 23 



face about plants, and thus cause them to 

 become yellow or to decay at the roots. 

 Soil suitable for growing vegetables usu- 

 ally gives good results, but extra care in 

 the selection and preparation of the soil 

 will be repaid in larger flowers, longer 

 stems, better colors, and a longer blooming 

 period. 



Preparation. The sweet pea is a deep- 

 rooting plant, and in order to provide 

 suitable conditions so that the effects of 

 drought will be overcome, the preparation 

 of the soil must be deep and thorough. 

 Whatever the nature of the soil, unques- 

 tionably the best preparation can be made 

 by trenching the soil in the autumn. This 

 means turning the soil to a depth ranging 

 from 18 inches to as much as three feet. 

 In America this method is usually found 

 too expensive, and instead a trench 15 to 

 18 inches wide along the line of the rows 



