Much difference of opinion prevails respecting the most suitable time for transplanting. Some prefer early in the spring, others late in the fall; and both parties are generally enabled to refer to successful results in support of their opinions. So much, indeed, depends on the weather immediately after planting, and on the care observed in performing the operation, that we not unfrequently hear of success having been attained, even at midsummer. It is probable, however, that if a series of comparative experiments were made, during several successive years, that one period would be found to afford more satisfactory results than any other.

I am inclined to believe that there is a certain period, or rather a certain stage in the plant's annual growth, when it it may be removed with a better prospect of success, than at any other time. My notions on this point do not, I am aware, exactly coincide with those of writers who are generally considered high authorities in gardening matters. I am the more desirous on that account, to state briefly in the pages of the Horticulturist, what are the facts and principles on which my opinions are founded, and if other readers of the Horticulturist, whose experience may differ from my own, or who may consider my theoretical views unsound, should forward to you a statement of their experience and objections, we might, in the end, be enabled to understand more clearly the causes of success or failure at different seasons, and be induced to make further inquiries, and more accurate observations, by means of which more correct views might ultimately prevail, and a more uniform and successful system of transplanting be established.

Lindley, in his Theory of Horticulture, considers that the most favorable time for transplanting, is during the months of November and December, or, between the fall of the leaf and the earliest part of spring, and chiefly for these reasons; because the roots of a plant are necessarily more or less injured in the process, and are consequently less able to support the stem, than they were before the mutilation took place; and in summer, when there is the greatest demand upon them, owing to the perspiration of the foliage, the roots are most essential; but in winter, when the leaves have fallen, they are comparatively unimportant, as is evident from a very common case. Let a limb of a tree be felled in full leaf, in June, its foliage will presently wither, the bark will dry up, and the whole will speedily perish; but if a similar limb be lopped off in November, when its foliage has naturally fallen off, it will exhibit no signs of death during winter, nor till the return of spring, when its efforts to recover, by the emission of leaves, only accelerates its end.

These two propensities are considered to include the roost essential parts of the theory of transplantation.

If the trees to be transplanted had to be carried a considerable distance, or were likely, through any cause, to remain unplanted several days, then I have no doubt that a greater number of plants would be found to live, and that the success upon the whole would be more satisfactory, if they were transplanted in November, when the leaves had fallen, than if they were transplanted at any other time of year. But if it is intended merely to transplant from one part of a garden to another, or from a nursery within a day's journey, as will generally be the case, then there seems to be good reasons for concluding, that providing the precautions in the "Theory of Horticulture" respecting the preservation of the roots, and the selection of a suitable day, be attended to, those plants will be found to succeed most perfectly, which are transplanted early in autumn, soon after the leaves begin to fall, but while a considerable quantity yet remain in a mature and efficient state I have been led to this conclusion, not only by the results of my own practice, but by considering the state in which the elaborated sap is deposited in the wood during winter; the changes this sap must undergo in early spring, to fit it to produce and support new leaves and roots; the necessity of efficient roots to produce this change, and the necessity of mature leaves to speedily repair the injury done to the roots, and to produce fresh fibres.

There is evidently a wide difference between transplanting a tree in summer, when it is in full leaf, and in autumn, when the leaves have partially fallen. In the former case, there would be so many adverse causes to contend with, that success would be very doubtful: there Would be long days would be considerably modified, the young wood would be nearly ripe, and in consequence of the diminished number of leaves, there must be a corresponding diminution in the supply of sap required from the roots; consequently, any mutilations which might take place, if trees were carefully transplanted, would not, it is reasonable to conclude, be felt to an injurious extent; by the action of the mature leaves which remained, the injuries which the leaves had sustained would be speedily repaired, new roots would be immediately produced, and the plants would be established before winter, and be prepared to grow with nearly, if not quite, their usual vigor in the following spring.

It is now generally known that leaves, in the first stage of their existence at least, and all other parts of a plant, are composed of and supported by matter which has been previously elaborated, or prepared by mature leaves. Every plant then contains within itself, during winter or its season of rest, a fund of organizable sap, by which its first emitted leaves, etc. are supported. It is not, however, stored up in a fluid, but in an inspissated or concrete state, and before it can be made available for the support of leaves, etc., it must be dissolved by aqueous sap absorbed by the roots previously to the unfolding of the leaves; and in proportion to the quantity of sap thus prepared, which a plant contains previously to the renewal of its growth in spring, so will be, in a great measure, the size and vigor of the first emitted leaves and shoots. The roots of plants, then, are obviously of great importance to them during winter as well as summer, and that season must therefore, I think, be the best for transplanting, which, with little risk of loss or injury from atmospheric influences, insures the speediest renovation of the roots.