428 THE PRINCIPLES OF FLORICULTURE 



middle of May, they are taken to the coldframes to harden 

 the tissue before planting in the open ground. Cannas 

 are used to follow bulbs or pansies in outdoor bedding, 

 therefore, they should be well developed when planted. 

 The plants should be set about one foot apart for mass 

 effects, but for general flowering effects they may be 

 from eighteen inches to two feet. Frequently, cannas are 

 planted among shrubs, often for the purpose of making 

 shrub plantings attractive before the shrubs have fully 

 developed. 



The flowers should be picked as soon as they wilt, and 

 so prevent the formation of seeds. Seed-production 

 shortens the flowering season, also the withered flowers 

 give the plants an untidy appearance. As soon as the 

 plants are frosted in the fall, they should be dug and left 

 on top of the ground for twenty-four hours if there is no 

 danger of a heavy freeze. The excess of soil should be 

 shaken off and the plants stored in dry sand with the tops 

 down. They may be stored the same way as Irish 

 potatoes. The roots should not become too warm, being 

 kept, if possible, in a temperature of 40 to 45. New 

 varieties are raised from seed which is usually sown in 

 March. The seed is so hard that it should be soaked in 

 lukewarm water for twenty-four hours, and then the 

 outer covering is cut to allow germination. 



721. Dahlias, botanical classification. Order, Com- 

 positse; genus, Dahlia (after Dahl, a Swedish botanist 

 who was a student of Linnaeus) ; species, rosea (variabilis), 

 coccinea and Juarezii. There are several different types, 

 as follows : 



(a) Show: The show type of dahlia has large, compact 

 flowers, double in center and regular in outline, as if grown 

 in a mold. They are solid, or self-colors or with a darker edge 

 than center. Some good varieties are : 



