(1) the balance between shrubs and trees
(2) the proportions of evergreen and deciduous kinds
(3) blending of habits and harmonizing of colours
(4) beauty for all seasons of the year
(5) the respective claims of many candidates for comparatively few places.
It may facilitate the accomplishment of a difficult task if we take an imaginary border and work our way round it, making suggestions for selection and arrangement as we go.
For the sake of completeness we will assume that shelter is required. Farther, we will assume that a nice selection of flowering and ornamental-leaved trees is required for the main area, associated with shrubs of dense habit for cover. Finally we will assume that groups of shrubs of brilliant colour or special interest are wanted for the front.
We work, therefore, on the basis of employing three distinct areas: at the back, an area of material for shelter; in the middle, an area for small trees and cover; at the front, an area for special shrubs. This at once gives us something tangible. It provides a definite idea of procedure.
Fig. A suggestion for treating an area of ground in front of a house. The main features are: a central oval of turf; on the left a wide border with a series of connected Rose pillars (1 to 17) along the middle, and shrubs on each side, a grass edging and a carriage drive; in the centre a screen clump of trees with groundwork of shrubs (18); on the right an accommodation road to the back of the house, a screen of trees (19), and a series of small flowering trees (20), with a groundwork of shrubs.
Needless to say, stiff, rectangular blocks are not contemplated. Let us work on flowing lines. The border shall vary in width and shall be broadest at those parts where, owing to exposure, the most shelter is required.
First as to this shelter. The planting of rows of trees has been deprecated. It gives a maximum of stiffness with a minimum of shelter. Groups are preferable to lines, and certainly at the points of greatest exposure clumps should be planted. At other points the belt may thin down almost to a single line.
The Austrian Pine (Pinus austriaca) is greatly in demand as a shelter tree on account of its hardiness, adaptability to most soils, including poor ground,fairly quick growth and dense habit. The principal point against it is its sombre appearance. When planted in quantity, and unrelieved, it is apt to have a gloomy effect. It is at its worst when planted, as one sometimes sees it, in a series of straight rows. When set in groups and brightened by an adjacent cluster of Silver Birch, an entirely different effect is produced. The Silver Birch is a graceful tree with clean, straight, even stems and beautiful bark. It is very hardy, and, while not quite so much at home as the Austrian Pine on the worst of soils, it is by no means exacting.
Other Pines than the Austrian are available. Pinus Lambertiana is one of the hardiest, and revels in the buffeting of the gales. Ponderosa is a glaucous species that will thrive in the poorest soil. Pinaster, the Cluster Pine, will also do in poor soil, and thrives near the sea. The Scotch Fir, Pinus sylvestris, is perhaps the best known of all, and does well on peaty soil. While the Pines are often effective as specimen trees, they are best grouped in clusters of five, seven or more, especially for shelter. Trees of brighter appearance, such as varieties of Elm and Poplar, may be planted near them. There are many good varieties of the common Elm (Ulmus campestris), notably variegata, a silver-leaved form; and antarctica aurea, a golden-leaved form. These make excellent companions to the Pines. The Necklace Poplar (Populus deltoidea, commonly known as canadensis) has a beautiful golden form called aurea, and this makes a good associate for sombre Pines or for the copper Beech. The last-named beautiful tree is quite good enough for a garden specimen, but when considerable areas are available for the shelter belts it may be planted there, with bright-leaved trees such as those mentioned adjacent. Of the Poplars, the white (Abele) is the best for damp sites, and the black (nigra) for drier places. They are both hardy trees, and the former often grows into fine specimens. The black Poplar has dark stems. It can be made to give low shelter very quickly if planted as a standard tree, and the head shortened in order to encourage back breaks; it then soon forms a spreading head from eight feet high upwards. The Lombardy Poplar is a form of it. The Aspen (P. tremula) is an interesting Poplar with ever-quivering leaves.
Fig. A suggestion for a lawn and surrounding, belts of shrubs and trees, illustrating the idea of planting in three areas or zones described in chapter 9.
Fig. A suggestion for a border of shurbs and trees beside a walk.
The Evergreen Oak, also known as the Holly or Holm Oak (Quercus Ilex), may be planted for shelter groups. It does not grow to a great height, but it is of dense habit and its foliage is evergreen. This again may be planted with bright-leaved deciduous trees as a companion, such as one of the Poplars, Elms or Beeches already mentioned. The deciduous trees give that glow and play of light and shade in summer which are so grateful in the garden. The Elms should be planted sparingly, especially at points near walks and cultivated quarters, because in the first place they are liable to cast their branches, and in the second they send out large numbers of greedy foraging roots.