CHAPTER XIII.

ON PRUNING.

"LA taille est une des opérations les plus importantes et les plus délicates du jardinage. Confiée communément à des ouvriers peu instruits, observée dans les résultats d'une pratique trop souvent irréfléchie, elle a dû nécessairement trouver des détracteurs même parmi les physiologistes. Il en eût sans doute été autrement, si on l'avait étudiée dans les jardins du petit nombre de praticiens qui ont su de nos jours la bien comprendre. Sagement basée sur les lois de la végétation, elle contribue, entre leurs mains, non seulement à régulariser la production des fruits, à en obtenir de plus beaux, mais encore à prolonger l'existence et la fécondité des arbres."

Nothing can be more just than these words, addressed to the Horticultural Society of Paris, by their President, M. Héricart de Thury; and, if they do not apply with as much force to our gardeners as to those of France, they do most fully to our foresters.

The quantity of timber that a tree forms, the amount and quality of its secretions, the brilliancy of its colours, the size of its flowers, and, in short, its whole beauty, depend upon the action of its branches and leaves, and their healthiness. The object of the pruner is to diminish the number of leaves and branches; whence it may be at once understood how delicate are the operations he has to practice, and how thorough a knowledge he ought to possess of all the laws which regulate the action of the organs of vegetation. If well directed, pruning is one of the most useful, and, if ill-directed, it is

362

PRINCIPLES OF PRUNING.

among the most mischievous, operations that can take place upon a plant.

The object of pruning is either to influence the production of flowers and fruit, or to augment the quantity of timber, These two purposes demand separate consideration.

A. Pruning for Flowers or Fruit.

When a portion of a healthy plant is cut off, all that sap which would have been expended in supporting the part removed is directed into the parts which remain, and more especially into those in the immediate vicinity of it. Thus, if the leading bud of a growing branch is stopped, the lateral buds, which would otherwise have been dormant, are made to sprout forth; and, if a growing branch is shortened, then the very lowest buds, which seldom push, are brought into action; hence the necessity, in pruning, of cutting a useless branch clean out; otherwise the removal of one branch is only the cause of the production of a great many others.

This effect of stopping does not always take place immediately; sometimes its first effect is to cause an accumulation of sap in a branch, which directs itself to the remaining buds, and organizes them against a future year. In ordinary cases, it is thus that spurs or short bearing-branches are obtained in great abundance. The growers of the Filbert, in Kent, procure in this way greater quantities of bearing wood than nature unassisted would produce; for, as the Filbert is always borne by the wood of a previous year, it is desirable that every bush should have as much of that wood as can be obtained, for which every thing else may be sacrificed; and such wood is readily secured by observing a continual system of shortening a young branch by two-thirds, the effect of which is to call all its lower buds into growth the succeeding year; and thus each shoot of bearing wood is compelled to produce many others. The Peach, by a somewhat similar system, has been made to bear fruit in unfavourable climates (Hort. Trans., ii. 366); and every gardener knows how universally it is applied to the Pear, Apple, Plum, and similar trees, and even to the Fig-tree.

BLEEDING MUST BE PREVENTED.

363

The influence produced upon one part by the abstraction of some other part, thus shown in the development of buds which would otherwise be dormant, is seen in many other ways. If all the fruit of a plant is abstracted one year when just forming, the fruit will be finer and more abundant the succeeding year, as happens when late frosts destroy our crops. If of many flowers one only is left, that one, fed by the sap intended for the others, becomes so much larger. If the late Figs, which never ripen, are abstracted, the early Figs the next year are more numerous and larger. If of two unequal branches, the stronger is shortened and stopped in its growth, the other becomes stronger; and this is one of the most useful facts connected with pruning, because it enables a skilful cultivator to equalise the rate of growth of all parts of a tree; and, as has been already stated, this is of the greatest consequence in the operation of budding. In fact, the utility of the practice, so common in the management of fruit-trees when very young, turns entirely upon this. A seedling tree has a hundred buds to support, and consequently the stem grows slowly, and the plant becomes bushy-headed: but, being cut down so as to leave only two or three buds, they spring upwards with great vigour, and, being reduced eventually to one, as happens practically, that one receives all the sap, which would otherwise be diverted into a hundred buds, and thrives accordingly, the bushy head being no longer found, but a clean straight stem instead. In the Oak and the Spanish Chestnut this is particularly conspicuous.

Nothing is more strictly to be guarded against than the disposition to bleed, which occurs in some plants when pruned, and to such an extent as to threaten them with death. In the Vine, in milky plants, and in most climbers or twiners, this is particularly conspicuous; and it is not unfrequently observed in fruit-trees with gummy or mucilaginous secretions, such as the Plum, the Peach, and other stone fruits. This property usually arises from the large size of the vessels through which sap is propelled at the periods of early growth, which vessels are unable, when cut through, to collapse sufficiently to close their own apertures, when they necessarily pour forth their

364

BLEEDING MUST BE PREVENTED.

fluid contents as long as the roots continue to absorb them from the soil. If this is allowed to continue, the system becomes so exhausted as to be unable to recover from the shock, and the plant will either become very unhealthy, or will die. The only mode of avoiding it is to take care never to wound such trees at the time when their sap first begins to flow; after a time, the demand upon the system by the leaves becomes so great that there is no surplus, and therefore bleeding does not take place when a wound is inflicted.

The Vine often bleeds excessively when pruned in an improper season, or when accidentally wounded; and, I believe, no mode of stopping the flow of the sap is at present known to gardeners. I therefore mention the following, which I discovered many years ago, and have always practised with success:-If to four parts of scraped cheese be added one part of calcined oyster shells, or other pure calcareous earth, and this composition be pressed strongly into the pores of the wood, the sap will instantly cease to flow; so that the largest branch may, of course, be taken off at any season with safety." (Knight, in Hort. Trans., i. 102.) Mr. Lowe proposes collodion as a remedy for bleeding, which he found to be readily prevented by smearing wounds, immediately, with the substance. To this operation, the substance seems admirably adapted, by reason of its adhesiveness, its impenetrability, and its excessive toughness. Whether it will stop the bleeding of Vines, Walnuts, and similar trees requires to be ascertained.

All these things show how necessary it is to perform the operations of pruning with care and discretion. But, in addition to the general facts already mentioned, there are others of a more special kind that require attention. The first thing to be thought of is the peculiar nature of the plant under operation, and the manner in which its special habits may render a special mode of pruning necessary. For example, the fruit of the Fig and Walnut is borne by the wood of the same season; that of the Vine and Filbert by that of the second season; and Pears, Apples, &c., by wood of some years' growth; it is clear that plants of these three kinds will each require a distinct plan of pruning for fruit.

The pruner has frequently no other object in view than that of thinning the branches so as to allow the free access of light and air to the fruit; and if this purpose is wisely followed, by

SEASON FOR PRUNING.

365

merely removing superfluous foliage, the end attained is highly useful: it is clear, however, that in order to arrive at this end, without committing injury to the tree which is operated on, it is indispensable that its exact mode of bearing fruit should be in the first instance clearly ascertained.

The period of ripening fruit is sometimes changed by skilful pruning, as in the case of the Raspberry, which may be made to bear a second crop of fruit in the autumn, after the first crop has been gathered. In order to effect this, the strongest canes, which in the ordinary course of things would bear a quantity of fruiting twigs, are cut down to within two or three eyes of the base; the laterals thus produced, being impelled into rapid growth by an exuberance of sap, are unable to form their fruitbuds so early as those twigs in which excessive growth is not thus produced, and consequently, while the latter fruit at one season, the others cannot reach a bearing state till some weeks later. Autumnal crops of summer Roses, and of Strawberries, have been sometimes procured by the destruction of the usual crop at a very early period of the season; the sap intended to nourish the flower-buds destroyed is, after their removal, expended in forming new flower-buds, which make their appearance at a later part of the year.

The season for pruning is usually midwinter, or at midsummer; the latter for the purpose of removing new superfluous branches, the former for thinning and arranging the several parts of a tree. It is, however, the practice, occasionally, to perform what is called the winter pruning early in the autumn, as in the case of the Gooseberry, and of the Vine when weak; and the effect is found to be, that the shoots of such plants, in the succeeding season, are stronger than they would have been had the pruning been performed at a much later season. This is necessarily so, as a little reflection will show. During the season of rest (winter) a plant continues to absorb food solely from the earth by its roots; and, if its branches are unpruned, the sap thus and then introduced into the system will be distributed equally all through it; let us say from b to ed and e in the accompanying diagram. If late pruning is had recourse to, and the branches from a to c d and e are