PLANTING AND SEEDING SEASONS 9 



(c) Herbaceous Perennials^ 



(d) Lawn Grasses " 



Greenhouse plants and the propagation of plants by seeding, ex- 

 cept as referring to lawn grasses, are not included because condi- 

 tions vary so widely in the same locality. 



Deciduous Trees, Shrubs, and Vines. The transplanting of 

 deciduous trees, shrubs, and vines is commonly carried out during their 

 dormant season. It is possible in the spring, however, to carry on 

 planting of deciduous woody plants, at a time when the local plants are 

 too far advanced to be moved, by the simple expedient of bringing 

 plants from a storage cellar or from a more northerly nursery where 

 they are still dormant. Again in the autumn, these same northerly 

 grown plants may be used to start planting work before the local 

 plants are matured and safe to move. Transplanting seasons are 

 not so much governed by north and south latitude as they are by 

 the condition of the plants, as explained in another paragraph under 

 discussion of life-zones. 



The beginning of the dormant period for woody deciduous plants 

 comes in the autumn when their wood is matured and ripened and the 

 leaves start to fall or to take on their autumn colouration. This occurs 

 early in such plants as lilacs, lindens, flowering currants, and horse- 

 chestnuts, and it will usually be found to occur late in some of the 

 plants which are said to be hard to move in the autumn, such as poplars 

 and silver maples. From the beginning of the dormant period in the 

 fall until the beginning of physiological activity in the spring, de- 

 ciduous plants may be moved at any time that the ground is in 

 proper condition and the temperature favourable. As a matter of ^ 

 practice, in the northern states this work is suspended entirely during a 

 normal winter, for about four months, except where large plants are 

 moved with a frozen ball of earth about their roots, because frozen 

 ground and snow make the operation of transplanting smaller plants 

 entirely impracticable. This period, longest in Maine and in the 

 section surrounding Minneapolis, lessens as one goes farther south, until 

 in Virginia and Georgia a continuous planting season extends without 

 interruption through the dormant period. 



It was early learned that the whole of North America could be 

 conveniently divided into seven transcontinental belts or life-zones, 

 based upon the length of the growing season, which has been defined 



