The uses to which pruning is applied are various; but most commonly it is intended either to improve the form of the tree, or to make it bear more flowers and fruit than it otherwise would do: it is also used for removing diseased or broken branches; and, in cases of transplanting, for proportioning the head to the roots.

Pruning to improve the form of a tree in pleasure-grounds, is only required in those cases where trees have grown under unfavourable circumstances, and where they have been too much drawn up, or distorted in any manner: but in useful plantations it is necessary to prepare trees for the purposes for which they are intended. Thus, for example, a tree intended for timber, should have its side-branches taken off while they are quite young, in order that the wounds may soon heal over, and not leave loose knots to weaken or disfigure the wood; while a tree intended for a screen should be allowed ample space for its branches to spread from the ground upwards, and then they should only be shortened at their extremities, to make them throw out short branches near the tree. In pleasure-grounds the principal object is generally either to preserve the shape of the tree or shrub, so that it may form an agreeable object on a lawn; or to let it combine in a group with others, either for ornament, or to serve as a screen or shelter. In the first case, it is obvious that no pruning is requisite, but to remove dead, diseased, or unsightly branches; and in the second, the pruning must depend upon the shape the tree is required to take to group well with the others planted near it.

Pruning to produce flowers or fruit has in view two objects: first, to cut off all superfluous wood, so as to throw the strength of the tree into the fruit-bearing branches; and secondly, to admit the sun and air into the interior of the tree to ripen and strengthen the wood. In both cases the attention of the pruner must be directed to thinning out weak and crowded shoots; and to keeping both the sides of the tree well balanced, in order that the circulation of the sap may be equal throughout. This will preserve the general health of the tree, at the same time that it throws the sap into the proper channels; and the fruit will be produced in as much abundance as can be done without injuring the tree. It should never be forgotten, that to effect permanent improvements, nature should be aided, not over-strained; and that all extraordinary exertions are succeeded by a period of feebleness and languor; or, if the exertion be continued too long, by death. Thus, all cases of pruning and training to produce fruit, should never be pushed too far: as though, by occasioning an extraordinary deposit of the returning sap in some particular part, that part may be forced into fruit, the unnatural deposit cannot fail in the end to engender disease.

Sometimes a tree, from being supplied with more food than it can digest, or from some other cause, has a tendency to produce what the English gardeners call water-shoots, and which the French call gourmands. These are strong, vigorous-growing branches, which are sent up from the main trunk of the tree, but which do not produce either flowers or fruit; and which, consequently, if the tree be full of wood, should be removed as soon as their true character is discovered. If, however, the tree have too little wood in the centre, or if it appear exhausted by too much bearing, these branches should be spared, as they will serve admirably both to fill up any blanks that may have been left in the training, and to strengthen the trunks and roots by the quantity of rich returning sap, which they will send down from their numerous leaves. A certain quantity of leaves and barren branches are essential to the health of every tree; and the fruit-grower who consults his own interest, should cherish them instead of grudging the sap required for their support. Whenever there is not a sufficient quantity of leaves to elaborate the sap, the fruit that ought to have been nourished by its rich juices, becomes flaccid and insipid; its skin grows tough instead of crisp; and if the deprivation of leaves has been carried to excess, the fruit never ripens, but withers prematurely, and falls off. Pruning, at the best, is a violent remedy; and, like all other violent remedies, if carried further than is absolutely necessary, it generally ends by destroying.

Training is intimately connected with pruning, and like it should always be used with caution. A trained tree is a most unnatural object; and whatever care may be taken of it, there can be no doubt that training shortens its life by many years. The principal object of training is to produce from a certain number of branches a greater quantity of fruit or flowers than would grow on them if the plant were left in a natural state; and this is effected by spreading and bending the branches, so as to form numerous depositions of the returning sap, aided, where the plant is trained against the wall, by the shelter and reflected heat which the wall affords. Thus the points to be attended to by the gardener in training are the covering of the wall, so that no part of it may be lost; the bending of the branches backwards and forwards, so that they may form numerous deposits of the returning sap; and the full exposure of the fruit-bearing branches to the sun and air. For these purposes the gardener shortens the long shoots, to make them throw out side-branches, with which he covers his walls, never suffering them to cross each other, but letting each be as much exposed to the influence of the air and light as is consistent with a necessary quantity of leaves; and he bends them in different directions to throw them into fruit. These general principles are common to all fruit-trees, but of course they must be modified to suit the habits of the different kinds. Thus, for example, some trees, such as the fig and the pomegranate, only bear on the extremities of their shoots; and, consequently, if their shoots were continually shortened, these trees would never bear at all; other trees, such as the apple and the pear, bear their fruit on short projecting branches, called spurs; and others at intervals on nearly all the branches, and close to the wall. All these habits should be known to the gardener, and the modes of training adopted which will be suitable to each. Training flowers should also be regulated by a knowledge of the habits of the plants; but it consists principally in checking their over-luxuriance of growth, and tying them to stakes or wooden frames. In all kinds of training, neatness is essentially requisite, and any departure from it is exceedingly offensive. Where the hand of art is so evident as it is in training, we require excessive neatness to make us amends for the loss of the graceful luxuriance of nature.

The operation of training against a wall is performed by the aid of nails and shreds; the shreds being narrow oblong pieces of list or cloth, put round the branches, and attached to the wall by nails driven in with a hammer. Care should be taken that the pieces of list are long enough to allow of the free passage of the sap, and yet not so long as to permit the branch to be so agitated by the wind as to bruise itself against the wall. The nails should also never be driven in so as to wound or corrode the bark; and when driving in the nails, the gardener should be very careful not to bruise the branch with his hammer. The shreds should be broad enough not to cut the bark, and yet not so broad as to cover the buds; and they should, as much as possible, be of some uniform and dark colour. As few shreds should be used as are sufficient to attain the end in view; but these should be very firmly attached, as nothing gives a more gloomy picture of misery and desolation in a garden, than trees that once were trained, having become detached, and hanging drooping from the wall. Sometimes wires are fastened to walls, to which the plants are tied with strands of bast mat; the strand, after it is put round the branch, and the wire being gently twisted between the finger and thumb, in order that it may make a firm knot without tearing or weakening the ligament. Climbing shrubs are tied to the pillars of a verandah, or to trellis work, in the same manner; as are also flowers to sticks, or slight wooden or wire frames, with the exception that, in their case, the bast does not require twisting.

Protecting from frost is an essential part of culture to a lady gardener, particularly in so uncertain a climate as that of England. Not only the blossoms of peaches and nectarines, and those of other early flowering fruit-trees, are liable to be injured by the spring frosts; but those of the tree pæony, and other beautiful shrubs, are frequently destroyed by them; and, unfortunately, many of the modes of protection, by knocking off and bruising the blossoms, are almost as injurious as the frosts that they are intended to guard against. Twisting a straw-rope round the trunk of the tree, and putting its ends into a bucket of water, is certainly a simple method, and it has been recommended as a very efficacious one. When a mat is used to protect wall trees, it does perhaps least injury to the blossoms, when curtain rings are sewed to its upper end, and it is hung by these on hold-fasts, or large hooks, driven into the upper part of the wall. To make it more secure, particularly in windy weather, it may be tied on the sides with bast to nails driven into the wall; and a broad moveable wooden coping should rest on the hold-fasts, and cover the space between the mat and the wall, to prevent injury from what are called perpendicular frosts. Camellias and many half-hardy shrubs may be protected by laying straw or litter round the roots; as the severest frosts seldom penetrate more than a few inches into the ground. Even in the severe winter of 1837-8, the ground was not frozen at the depth of ten inches. Tree pæonies, and other tender shrubs, that are in a growing state, very early in the spring, may be protected by coverings of basket work, which are sufficiently large and light to be lifted off in fine days. Hand and bell glasses, sea-kale pots, and wooden frames covered with oiled paper are all useful for protecting small plants.

Insects, and Snails and Slugs are the terror of all gardeners; and the destruction they effect in some seasons in small gardens is almost beyond the bounds of credibility. Birds do comparatively little injury, and indeed all the soft-billed kinds (which fortunately include most of the sweetest songsters) do good. The willow and common wrens, the blackcap, the nightingale, the redstart, all the warblers and fly-catchers, the swallows and martins, the wagtails, the wryneck, the tomtit, the fern owl or night jar, and many others, live almost entirely on insects, and destroy great numbers every year: while the blackbird and the thrush, the robin and the sparrows, though they devour a portion of the fruit, destroy insects also. All birds may indeed be safely encouraged in small gardens near towns, as they will do much more good than injury; and a few cherries and currants are a cheap price to pay for their delightful songs.

As it is the larvæ only of insects, with very few exceptions, that do injury to vegetation, many persons never think of destroying them in any other state; forgetting that every butterfly that we see fluttering about may lay thousands of eggs, and that if we wait till these eggs have become caterpillars, irreparable mischief will be done to our plants before they can possibly be destroyed. Whenever a butterfly is seen quietly sitting on the branch of a tree, in the daytime, it will generally be found to be a female, that either just has laid, or what is more probable, is just about to lay her eggs. As soon as the eggs are laid, the butterfly generally dies; and where dead butterflies are found, search should always be made for their eggs. In summer, a little oblong chrysalis, the colour of which is yellow, with black bands, will frequently be found hanging from the gooseberry-bushes; and whenever it is seen it should be destroyed. This chrysalis is the pupa of the magpie moth, the caterpillar of which frequently strips the gooseberry-bushes of all their leaves in spring, and thus renders their fruit worthless in summer. The lackey caterpillar is another very destructive insect. These creatures, which are curiously striped, like the tags on a footman’s shoulder, (whence their name,) assemble together in great numbers, and covering themselves with a web, completely devour the epidermis and parenchyma of the leaf on which they have fixed themselves; they then draw another leaf to them, which they also devour, and then another, till the greater part of the leaves of the tree they have attacked, present a fine lace-like appearance, as though they had been macerated. Did all these insects live to become moths, they would completely destroy not only our gardens, but our forests, as they feed on almost every different kind of tree; but with that beautiful arrangement by which all the works of our Great Creator are balanced equally with each other, and none allowed to predominate, these insects are such favourite food for birds, that not a hundredth part of them are suffered to reach maturity. The eggs of the lackey moth are often found fixed on a naked twig, in winter, looking like a bracelet of hard beads, and adhering so firmly together, that the whole bracelet may be slipped off entire.

The cabbage butterflies are also very destructive in the larva state. The caterpillars are soft, of a pale whitish green, and very active, leaping about in the hand when taken; and the chrysalis, which is also green, looks as if it were swathed up like a mummy. The caterpillar of the beautiful little ermine moth is a gregarious feeder, like the lackey caterpillar, and is nearly as destructive; and it is the more necessary to mention this, because the moth itself is so small, so delicate, and so quiet, that no one unacquainted with its habits would think of killing it as an injurious insect.