A very important question in the proper development of a lawn is how to give it a background and suitable enclosure of trees and shrubs. This chapter is especially concerned with the types of shrubs which are used as masses of planting in the shrub borders. These shrubs may be used in isolated groups or in a continuous border, the object of either method of arrangement being to provide a frame for the picture.
There are two types of lawns: the refined lawn area, and the more natural lawn area which fits into the existing landscape and which is not kept as well mowed and as neatly edged. The refined lawn area requires a type of shrub planting which must be neat in its outlines, possessing an interesting touch of foliage, flowers, and fruit, and naturally making a compact mass. This material is usually selected from the refined types of nursery-grown stock such as spirea, privet, snowball, golden bell, honeysuckle, and mock-orange.
In every border planting, if carefully analyzed, there will be found three distinct types of shrubs: those which are tall growing, averaging from seven to ten feet in height; those which are of medium growth, averaging from four to seven feet in height; and those which are low growing, averaging from two to four feet in height. It is essential properly to group these shrubs in order to have a compact foliage effect carrying from the higher shrubs through the lower shrubs to meet the turf.
It is very important, however, in the grouping of the different types of low, medium, and tall-growing shrubs in refined plantings not only to know the normal height which the shrubs attain but to know whether the foliage texture on one shrub is extremely fine and that on another shrub extremely coarse. For instance, the Japanese barberry is not used to the best advantage in front of the coarser, medium-growing varieties of flowering currant, sumac, or viburnum. It is much better adapted for use in front of the spirea, white kerria, and privet, shrubs with smaller types of foliage. The reason is that the sudden transition from the extremely coarse texture of foliage to the extremely fine texture of foliage creates a discord in the landscape picture.
There are many of the shrubs contained in the second group which are those used to compose border plantations on a large scale where the detailed study of the planting is not its most important side, but rather where the general mass effects seen at a distance produce the interesting effect. Shrubs which are selected for border planting on the refined lawn areas, which are usually much more restricted than the extensive lawns, must stand the test of detailed study at the same time that they prove their value as mass effects.
The shrubs which are valuable for the less-refined and extensive lawn areas may consist of some of the shrubs for refined lawn plantings, such as the snowballs and the honeysuckles; but in general many of these shrubs are more or less native and generally collected locally. It is a difficult task to define the material which should be used in border plantings on the larger lawn areas where the coarser mass effects will meet the requirements. In general, most of the shrubs which are adapted to plantings on the refined lawn areas are adapted to the second type of plantings; but not all of the shrubs included in the second group and adapted to the more unrefined lawn areas are adapted in any way to use on the limited refined lawn areas.