This is an occupation requiring much attention and constant care. Bulbous roots are propagated by offsets; some growing on the top, others around the sides. Many plants are propagated by cutting off twigs, and setting them in earth, so that two or three eyes are covered. To do this, select a side shoot, ten inches long, two inches of it being of the preceding year's growth, and the rest the growth of the season when it is set. Do this when the sap is running, and put a piece of crockery at the bottom of the shoot when it is buried. One eye, at least, must be under the soil. Water it, and shade it in hot weather.
Plants are also propagated by layers. To do this, take a shoot which comes up near the root, bend it down so as to bring several eyes under the soil, leaving the top above-ground. If the shoot be cut half through, in a slanting direction, at one of these eyes, before burying it, the result is more certain. Roses, honeysuckles, and many other shrubs are readily propagated thus. They will generally take root by being simply buried; but cutting them as here directed is the best method. Layers are more certain than cuttings.
Budding and Grafting, for all woody plants, are favorite methods of propagation. In all such plants there is an outer and inner bark, the latter containing the sap vessels, in which the nourishment of the tree ascends. The success of grafting or inoculating consists in so placing the bud or graft that the sap vessels of the inner bark shall exactly join those of the plant into which they are grafted, so that the sap may pass from one into the other.
The following are directions for budding, which may be performed at any time from July to September:
Select a smooth place on the stock into which you are to insert the bud. Make a horizontal cut across the rind through to the firm wood; and from the middle of this, make a slit downward perpendicularly, an inch or more long, through to the wood. Raise the bark of the stock on each side of the perpendicular cut, for the admission of the bud, as is shown in the annexed cut, (Figure 64). Then take a shoot of this year's growth, and slice from it a bud, taking an inch below and an inch above it, and some portion of the wood under it. Then carefully slip off the woody part under the bud. Examine whether the eye or germ of the bud be perfect. If a little hole appear in that part, the bud has lost its root, and another must be selected. Insert the bud, so that a, of the bud, shall pass to a, of the stock; then b, of the bud, must be cut off, to match the cut b, in the stock, and fitted exactly to it, as it is this alone which insures success. Bind the parts with fresh bass or woolen yarn, beginning a little below the bottom of the perpendicular slit, and winding it closely around every part, except just over the eye of the bud, until you arrive above the horizontal cut. Do not bind it too tightly, but just sufficient to exclude air, sun, and wet. This is to be removed after the bud is firmly fixed and begins to grow.
Seed-fruit can be budded into any other seed fruit, and stone-fruit into any other stone-fruit; but stone and seed fruits can not be thus mingled.
Rose-bushes can have a variety of kinds budded into the same stock. Hardy roots are the best stocks. The branch above the bud must be cut off the next March or April after the bud is put in. Apples and pears are more easily propagated by ingrafting than by budding.
Ingrafting is a similar process to budding, with this advantage, that it can be performed on large trees; whereas budding can be applied only on small ones. The two common kinds of ingrafting are whip-grafting and split-grafting. The first kind is for young trees, and the other for large ones.
The time for ingrafting is from May to October. The cuttings must be taken from horizontal shoots, between Christmas and March, and kept in a damp cellar. In performing the operation, cut off in a sloping direction (as seen in Fig. 65) the tree or limb to be grafted. Then cut off in a corresponding slant the slip to be grafted on. Then put them together, so that the inner bark of each shall match exactly on one side, and tie them firmly together with yellow yarn. It is not essential that both be of equal size; if the bark of each meet together exactly on one side, it answers the purpose. But the two must not differ much in size. The slope should be an inch and a half, or more, in length. After they are tied together, the place should be covered with a salve or composition of bees-wax and rosin. A mixture of clay and cow-dung will answer the same purpose. This last must be tied on with a cloth. Grafting is more convenient than budding, as grafts can be sent from a great distance; whereas buds must be taken in July or August, from a shoot of the present year's growth, and can not be sent to any great distance.
The next cut (Fig. 66) exhibits the mode called stock-grafting; a being the limb of a large tree, which is sawed off and split, and is to be held open by a small wedge till the grafts are put in. A graft inserted in the limb is shown at b, and at c is one not inserted, but designed to be put in at d, as two grafts can be put into a large stock. In inserting the graft, be careful to make the edge of the inner bark of the graft meet exactly the edge of the inner bark of the stock; for on this success depends. After the grafts are put in, the wedge must be withdrawn, and the whole of the stock be covered with the thick salve or composition before mentioned, reaching from where the grafts are inserted to the bottom of the slit. Be careful not to knock or move the grafts after they are put in.
Pruning is an operation of constant exercise, for keeping plants and trees in good condition. The following rules are from a distinguished horticulturist: Prune off all dead wood, and all the little twigs on the main limbs. Retrench branches, so as to give light and ventilation to the interior of the tree. Cut out the straight and perpendicular shoots which give little or no fruit; while those which are most nearly horizontal, and somewhat curving, give fruit abundantly and of good quality, and should be sustained. Superfluous and ill-placed buds may be rubbed off at any time; and no buds pushing out after midsummer should be spared. In choosing between shoots to be retained, preserve the lowest placed, and on lateral shoots those which are nearest the origin. When branches cross each other so as to rub, remove one or the other. Remove all suckers from the roots of trees or shrubs. Prune after the sap is in full circulation, (except in the case of grapes,) as the wounds then heal best. Some think it best to prune before the sap begins to run. Priming-shears, and a pruning-pole, with a chisel at the end, can be procured of those who deal in agricultural utensils.
Thinning is also an important but very delicate operation. As it is the office of the leaves to absorb nourishment from the atmosphere, they should never be removed, except to mature the wood or fruit. In doing this, remove such leaves as shade the fruit, as soon as it is ready to ripen. To do it earlier impairs the growth. Do it gradually at two different times. Thinning the fruit is important, as tending to increase its size and flavor, and also to promote the longevity of the tree. If the fruit be thickly set, take off one half at the time of setting. Revise in June, and then in July, taking off all that may be spared. One very large apple to every square foot is a rule that may be a sort of guide in other cases. According to this, two hundred large apples would be allowed to a tree whose extent is fifteen feet by twelve. If any person think this thinning excessive, let him try two similar trees, and thin one as directed and leave the other unthinned. It will be found that the thinned tree will produce an equal weight, and fruit of much finer flavor.