Pruning is necessary to keep plants in shape, to make them more floriferous and fruitful, and to hold them within bounds.
Even annual plants often may be pruned to advantage. This is true of tomatoes, from which the superfluous or crowding shoots may be removed, especially if the land is so rich that they grow very luxuriantly; sometimes they are trained to a single stem and most of the side shoots are taken away as they appear. If plants of marigold, gaillardia, or other strong and spreading growers are held by stakes or wire-holders (a good practice), it may be advisable to remove the weak and sprawling shoots. Balsams give better results when side shoots are taken off. The removing of the old flowers, which is to be advised with flower-garden plants (page 116), is also a species of pruning.
Distinction should be made between pruning and shearing. Plants are sheared into given shapes. This may be necessary in bedding-plants, and occasionally when a formal effect is desired in shrubs and trees; but the best taste is displayed, in the vast majority of cases, in allowing the plants to assume their natural habits, merely keeping them shapely, cutting out old or dead wood, and, in some cases, preventing such crowding of shoots as will reduce the size of the bloom. The common practice of shearing shrubbery is very much to be reprehended; this subject is discussed from another point of view on page 24.
The pruner should know the flower-bearing habit of the plant that he prunes,--whether the bloom is on the shoots of last season or on the new wood of the present season, and whether the flower-buds of spring-blooming plants are separate from the leaf-buds. A very little careful observation will determine these points for any plant. (1) The spring-blooming woody plants usually produce their flowers from buds perfected the fall before and remaining dormant over winter. This is true of most fruit-trees, and such shrubs as lilac, forsythia, tree peony, wistaria, some spireas and viburnums, weigela, deutzia. Cutting back the shoots of these plants early in spring or late in fall, therefore, removes the bloom. The proper time to prune such plants (unless one intends to reduce or thin the bloom) is just after the flowering season. (2) The summer-blooming woody plants usually produce their flowers on shoots that grow early in the same season. This is true of grapes, quince, hybrid perpetual roses, shrubby hibiscus, crape myrtle, mock orange, hydrangea (paniculata), and others. Pruning in winter or early spring to secure strong new shoots is, therefore, the proper procedure in these cases.
Remarks on pruning may be found under the discussion of roses and other plants in subsequent chapters, when the plants need any special or peculiar attention.
Fruit-trees and shade-trees are usually pruned in winter, preferably late in winter, or in very early spring. However, there is usually no objection to moderate pruning at any time of the year; and moderate pruning every year, rather than violent pruning in occasional years, is to be advised. It is an old idea that summer pruning tends to favor the production of fruit-buds and therefore to make for fruitfulness; there is undoubtedly truth in this, but it must be remembered that fruitfulness is not the result of one treatment or condition, but of all the conditions under which the plant lives.
All limbs should be removed close to the branch or trunk from which they arise, and the surface of the wound should be practically parallel with such branch or trunk, rather than to be cut back to stubs. The stubs do not heal readily.
All wounds much above an inch across may be protected by a coat of good linseed-oil paint; but smaller wounds, if the tree is vigorous, usually require no protection. The object of the paint is to protect the wound from cracking and decay until the healing tissue covers it.
Superfluous and interfering branches should be removed from fruit-trees, so that the top will be fairly open to sun and to the pickers. Well-pruned trees allow of an even distribution and uniform development of the fruit. Watersprouts and suckers should be removed as soon as they are discovered. How open the top may be, will depend on the climate. In the West, open trees suffer from sun-scald.
The fruit-bearing habit of the fruit-tree must be considered in the pruning. The pruner should be able to distinguish fruit-buds from leaf-buds in such species as cherries, plums, apricot, peach, pear, apple, and so prune as to spare these buds or to thin them understandingly. The fruit-buds are distinguished by their position on the tree and by their size and shape. They may be on distinct "spurs" or short branches, in all the above fruits; or, as in the peach, they may be chiefly lateral on the new shoots (in the peach, the fruit-buds are usually two at a node and with a leaf-bud between them), or, as sometimes in apples and pears, they may be at the ends of last year's growths. Fruit-buds are usually thicker, or "fatter," than leaf-buds, and often fuzzy. Heading-back the tree of course tends to concentrate the fruit-buds and to keep them nearer the center of the tree-top; but heading-back must be combined with intelligent saving and thinning of the interior shoots. Heading-back of pears and peaches and plums is usually a very desirable practice.