SETTING off the garden picture, or any other landscape com position, from its surroundings is a basic principle of design. No arrangement of plants, however lovely in itself, can be properly appreciated, if your attention is continually being distracted. Furthermore, enclosure gives a pleasant feeling of privacy.

Where there is room, shrub borders provide the best gar den enclosure. The variety in form, texture, color, and density among shrubs complement plant arrangement within the gar den itself. When space is at a premium, the properly designed shrub border becomes an impossibility, but there are other means of enclosure. The very narrow shrub border consisting of only a staggered line of shrubs is not a border at all, and is rarely effective as enclosure or for its own sake. It is too low, too thin to be a screen and without sufficient space, an interesting skyline and contour cannot be developed. Further more, a thin border consisting of several species will lack unity and massiveness; if made up of one or two sorts it will be monotonous. To be effective, a shrub border should not be less than ten feet at its narrowest point, and in some places much wider, even up to twenty-five feet.

To design an effective border, you should employ some of each of four types of material. You will need mass plants for bulk and stability, interest plants for bloom and foliage ef fects, accent plants for contrast, and some filler material be tween the more important plants to use for immediate effect.

Mass Plants and How to Use Them

Mass plants are those species that present good solid foli age masses throughout the growing season, are rounded in form, furnish themselves well to the ground, and have a suffi ciently clean-growing habit to be attractive in winter, when foliage is absent. Viburnum dentatum is a typical mass shrub, but corylus, alder, Regels privet, aronia, calycanthus, acan thopanax (aralia), and the bush honeysuckles are also good for mass. About half of the shrub border should be of this type, arranged in groups of five to fifteen plants, depending on the size of the border. Unless such fair-sized groups of one species are used, the effect is spotty. (Plate 24)

Interest Plants

Interest plants may be defined as those having conspicuous foliage, flowers, or fruit. They include the common lilac, weigela, philadelphus, some of the larger bush roses, deutzia, forsythia, and althea; the more unusual caryopteris, Ilex ver ticillata, Viburnum tomentosum, plicatum, and sieboldi, sym plocos, and shrubs having red, purple, yellow, or variegated foliage. About a quarter of the whole planting should be made up of these species, used singly or in groups of three to five among the mass plants.