One of the most common mistakes on the part of the novice in gardening is to think that any plant can be made to grow anywhere. When initial mistakes in planting are made in the herbaceous borders, the plant either dies or becomes sickly, and it is then removed either to the bonfire or to a more congenial border, and its place taken by something more suitable.
Replacements of this kind are simple among the smaller plants, but when it comes to trees, mistakes cannot so easily be rectified. It is, therefore, very important that full understanding of the problem should be attained in the early days of garden planting. As with most garden problems, we can turn to nature for a solution.
Trees growing in the wild garden of nature sort themselves out by processes of natural selection. Certain trees thrive best in certain soils or in certain districts, in sheltered or exposed positions, etc. etc., and these trees, naturally adapted to the conditions, will oust their rivals. So we find that alders and willows group themselves by riversides, and that bay trees flourish on the warm chalk downs of the southern counties and the Isle of Wight. We find that Scotch pine grows in sandy soil in all districts of the British Isles. We find rhododendrons growing freely in woods in lime-free or peaty soils, and birches growing almost anywhere.
Such observations help us to choose trees for the particular kind of soil and situation at our disposal. At the same time, there may be special reasons why trees not exactly suited to the soil are desirable. As a rule it is best to keep to the species we know will thrive in the garden, but if for any reason we want others, there are ways of improving the existing conditions.
For instance, if the natural soil of the garden is stiff clay, and we specially want to plant in it a strawberry tree (arbutus unedo), we can do so, provided the tree is given a good start in soil congenial to it. The strawberry tree prefers a somewhat peaty soil, well worked. To establish it in a clay soil garden therefore, a deep wide hole should first be excavated, say 3 ft. deep and 4 or 5 ft. square. The roughest material available will be thrown in at the bottom, and over this should be put either some fresh, imported soil of light leafy or peaty nature, or the excavated clay soil, sifted and mixed with leaf-mould and sand. Planted like this, the tree will establish itself without difficulty.
It would, on the other hand, be useless to plant rhododendron the same way on a garden of chalky soil, for it must be remember that rhododendrons hate lime or chalk, and will not live in it. The roots of large trees travel a long way through the soil beyond the extent to which the branches spread—they would in few years penetrate the chalk, and the rhododendron wo immediately sicken and die. It will be seen that there are limitation to planting, and that it is not possible altogether to overrule natural limitations by human effort. So that on the whole the best advice to any gardener is to find out what trees are likely to thrive in particular soil and situation, and to keep mainly to them.
Some trees not only need special soil, but definitely need a special situation in the garden design. For instance, the well-known monkey puzzle tree (araucaria imbricata) should not be grown in mixed group; it demands an open space to itself. In the same many of the conifers should be planted as specimen trees, on a lawn, if possible, so that the full beauty of their mature symmetry can be appreciated.
One very important point in the selection of trees for garden decoration is to look ahead and choose them for their use when mature. Too often one sees a grey poplar set in a small garden where it must either become a nuisance or be constantly mutilated.
