A correspondent calls our attention to an article in the Garden of London, to some capital hints on planting trees and shrubs. They are so exactly in accord with our own teachings, and so timely, that we cannot do better than adopt them here as our "Seasonable Hints" for January :

"The dotting style of planting trees is cold as well as meager; nevertheless it has its uses; it shows what individual plants can become under difficulties. It also brings individual specimens and species into the sharpest contrast. It has also enabled cultivators to grow the largest number of species and varieties within a given area. Useful as a school in which something may be learned about trees, it is worse than useless as a means of improving landscape effects; nay, more, the dotting plan mars every landscape on which it is practiced. What play of light, or shadow, or repose, could be obtained by a series of dots, even though they consisted of trees faultless in form and symmetry? Trees so disposed might be enjoyed as specimens, but a pleasing landscape consisting of solitary trees is plainly an impossibility. Not only, however, is the dotting style inimical to landscape beauty, but it is also opposed to cultural perfection.

"Trees and shrubs are gregarious by nature, and if we compel them to grow in solitary isolation, we must take the consequences; and we do so in the form of slow and stunted growth in summer, or of ruthless destruction by cold in winter. It is not good for trees to grow alone. Each wind that blows beats against them with full force; the sun and dry air drain each leaf and bough of its rich juices, and, worse than all, the extremes of heat and cold do their worst as regards the exposed roots. This exposure of the roots to direct solar and atmospheric influence is altogether unnatural, and consequently injurious. But there is no need to rest the case on such general statements. It is only necessary to trace the palpable effects of the frost throughout our pleasure grounds, after an exceptionally hard winter, to discover that the single trees are often cut down, while groups of the self-same sorts escape unhurt. The seeming exceptions but confirm the rule.

"These exceptional groups killed or injured will be found in a lower situation or a moister locality. In the former the air is colder, as cold air will shoot down valleys into plains with as much certainty as a stone will roll down a hill; in the latter the plants are also more tender. Excessive moisture may help growth, but it hinders maturity, and it is maturity that enables plants to withstand cold. Hence it follows that groups may in such exceptional localities be cut down, while single trees at a higher level, if more thoroughly matured, may escape. But let the threefold conditions of soil, site, and maturity be alike, and the results will be wholly in favor of the groups. It is necessary, however, to bear in mind that there are 'groups and groups.' It is not only possible, but easy, to render groups tender by overcrowding or over-feeding, and when such is the case, groups may be swept away by a frost that will hardly brown the leaves of a solitary tree. It may be well to add that excessive stimulation, from whatever cause, results in weakness, that leaves the plants more liable to injury from cold than more hardy treatment.

"The object, however, is to show that, the conditions of growth being the same, Conifers planted in groups endure winters better than those dotted about singly. There is more than one reason for this; the tops are warmer and so are the roots. Planters can scarcely realize the amount of shelter that plants afford each other when planted in groups. Most plants are crippled or killed from the roots upwards, and not from the tops downwards. This is what kills isolated trees. The best roots are often considerably beyond range of the tops. Of course, the feeding roots sweep out, and are, in ever-widening areas, in search of new and better food. Just then the frost comes down upon them with full power, and either paralyzes, or kills them. Old roots might be frost-proof, but young ones are not. The former deprived of the latter are as useless as detached gas or water pipes cut off from the mains. The collecting roots being crippled or killed, the main ones become useless, and the tree begins to languish and die, or, in other words, is starved by the amount of cold at its most sensitive extremities, which planting in groups would have protected most effectually.

There is another powerful inducement to planting in groups.

"The dead leaves may be left to protect the roots along with the overshadowing tops. The former, in many cases, would afford the better protection. It is astonishing how many leaves fall off Coniferae just before winter; whole bar-rowloads of withered leaves lie under large trees of Pinus excelsa, P. Sabiniana, P. macrocarpa, and others. Under single trees these are, in most cases, carefully swept or raked up, as so much unsightly litter, or are blown away by the wind. This is simply to lay the most sensitive part of the tree open to the cold. In a state of nature these dead leaves accumulate to such an extent as to cover the ground under the trees ankle deep. They decompose very slowly, and their texture, form, and non-conducting powers are such that a very thin layer of them forms a frost-proof barrier. I have proved this, and no one who has not noted the power of the tops above and leaves below to resist cold could form a proper estimate of their potency. In group planting there is no temptation to remove the dead leaves, and the wind is powerless to drive them out.

Hence trees in groups cannot suffer at the roots, and, as a rule, they winter safely".