118 ARTIFICIAL ADAPTATIONS OF 



tivated as for a row of garden vegetables. The arbor-vitaes grow 

 so naturally into a hedge-form, that little skill is required to shape 

 them. The hemlock and other evergreens require much more 

 attention. 



Where it is necessary to have a high screen without delay, we 

 would plant the Norway spruce, and let it grow pretty nearly in a 

 natural way, until it reaches the height needed. The plants need 

 not be nearer than two feet apart, and are apt to grow more evenly 

 when small trees — say from one to two feet high — are planted. 

 Those which grow fastest must be kept back to the same rate of 

 growth as the weakest, or the former will in a few years over-top 

 and kill out the latter. Further than for this purpose, the lower 

 branches should not be cut back unless the top is also cut. A ver- 

 dant wall of Norway spruce twelve feet high may be grown in six 

 years from the time of planting, and must be allowed three or four 

 feet on each side of the stems for the lateral extension of the lower 

 branches. When the required height is attained, the tops can be 

 kept cut to it, and both sides dipt back to the form of the section 

 of a cone, the base of which is equal to half its height. The screen 

 can thereafter be cut late every June, so as to leave but an inch or 

 two of the last growth, and again in September if a second growth 

 has pushed strongly. 



It is seldom desirable to make topiary screens more than ten 

 or twelve feet high, as the trouble and expense of clipping them 

 from a movable scaffold is considerable. Where there is need, 

 and room, for higher screens, the object may be attained less 

 expensively and less formally with groups and belts of pines and 

 firs. But it happens sometimes that a screen of considerable 

 height is required where there is not ground to spare for the 

 growth of trees in a natural way ; and in such cases it is practi- 

 cable to form Norway spruce hedges to any height at which they 

 can be clipped, and without occupying for the base of the hedge 

 more than from six to ten feet in width. 



In general, hedges should be within a height that a man 

 on the ground, with the proper instrument, can cut any part of 

 them. 



For evergreen hedges of a defensive character, that is to say, 



