Grafting differs from budding, in the scion consisting of several buds instead of one. It is also performed at a different time of the year; as March and April are the proper seasons for grafting, whereas budding is never performed till after Midsummer. In grafting, sometimes the head of the stock is cut off, and sometimes only the branch, and the scion is selected according to the size of the part to which it is to be attached. When the scion and the stock have been both chosen, they are cut slantingly, so that one may fit into the other; and care being taken that the bark and soft wood of the two unite, at least on one side, the two pieces are bound together, and the ligature is covered with what is called grafting clay, that is, a mixture of stiff clay, with a fourth part of fresh horse-dung, and a small quantity of cut hay. Another kind of grafting clay is composed of equal parts of stiff clay and cow-dung. It is of very little consequence whether the scion and the stock are of the same diameter, provided they are so cut and fitted, as to leave no vacuity between them, in those parts where the union is to be effected; and, to keep them quite closely attached to each other, it is customary to form a tongue, or little projecting part, by making a slanting cut in the scion, and to make a corresponding slit in the stock to receive it. There are several kinds of grafting; but that which I have described, and which is called whip or tongue grafting, is the most common, and it is always performed with the firm or ripened wood. There is, however, another kind of grafting, now becoming common in the nurseries, which is performed with the young, or unripened wood, and this is called herbaceous grafting, because the parts of the stem with which it is performed are as succulent as the stems of herbaceous plants. In this kind of grafting, the shoot of the stock is broken off about two inches below the point, and all the leaves are taken off except two, one on each side, which are left to draw up the sap. The stock is then split with a very sharp knife between the leaves left on it; and, the base of the scion having been cut into a wedge-shape, it is fixed into the cleft made in the stock, which is bound tightly up with strips of cerecloth, or coarse cotton cloth covered with grafting wax, made of equal parts of turpentine, bees' wax and rosin, with a little tallow, melted together. Sometimes plants, especially camellias in pots, are grafted in this manner, and placed in a hothouse under hand-glasses, and the pot surrounded with moss, to keep the cutting as close as possible. This mode of grafting is of French origin, and it is called la greffe etouffée.
Inarching bears considerable resemblance to layering, as it is performed without separating the part which is to form the new plant. A branch is bent from a living plant, and partly cut through, and, the tongue thus formed being introduced into a slit made in another plant, the two are bound closely together. It is obvious that this mode of grafting, which is called inarching, can only be practised with plants in pots, as it requires the two plants that are to be united to be brought close together, and to remain so till the graft has taken effect.
You must observe that, in all kinds of grafting and budding, there must be a considerable degree of resemblance between the scion and the stock, for the graft to take effect. Thus, though one stoned fruit may be grafted on another, such as the almond or peach on the plum, a stoned fruit cannot be grafted on a kerneled fruit, such as a plum on an apple or a pear. In the like manner, an apple cannot be grafted on an orange, which was formerly supposed to be done, to produce a pomegranate; nor a rose on a black currant, which it was formerly believed would produce a black rose. It is true that plants are sometimes sold in Italy which appear to have been unnaturally grafted, such as a rose upon an orange; but it will be found, when closely examined, that the pith of the orange has been artfully scooped out, and the stem of the rose tree introduced into the hollow space thus formed, through a hole made in the stem close to the root. In this way the two plants may appear to be one for some time; as the stem of the orange tree will live and produce leaves two or three years after the pith is removed, provided the operation has been performed carefully.
The other operations of gardening are pruning and training, and, as I have already spoken of these when treating of the different trees, I have only to add here that the great art in pruning is to give a clean sloping cut without bruising the bark, as nature will make an effort to cover the wound if the edges of the bark are left in a healthy state. The use of a sloping cut is, to prevent the water from lodging on a wounded part. Trees should never be cut in a hard frost; and as little as possible in summer, as every branch taken off while the plant is in a growing state excites it to make fresh efforts to throw out new shoots. Many persons look over their trees in summer, and rub off all the buds which they think likely to produce useless shoots; and this practice, which is called disbudding, is a very good one, as it prevents the tree from wasting its strength unnecessarily. The principal object to be attained in training a fruit tree is, to make the plant produce as much fruit as possible; and for this purpose the branches are bent backwards and forwards to cause obstructions in the sap, as it is only from places where there is an accumulation of sap that flowers and fruit are produced. Another object in training standard trees is to let the air into the centre of the tree, so that it may ripen the wood; and a secondary object in training trees against a wall is, that every part of the wall may be covered.
I cannot quit the subject of gardening without saying a few words on manures. The object of manuring ground is, to supply the soil with certain properties which are necessary for the nutrition of the plants, and this is done partly by mixing with it some kind of animal or of vegetable manure, and partly by adding some earth, in which the soil of the garden may be deficient. The new manures which have lately been so fashionable are of both kinds: guano is the dung of sea birds, which has been accumulating for ages on islands off the western coasts of Africa and South America; and nitrate of soda and Humphrey's compound are mineral substances which are very efficacious in promoting vegetation. The best vegetable manure is formed from decayed leaves, and this is a manure which may always be used with perfect safety; whereas the others are very injurious if used in too huge a quantity.
No kind of animal manure should be used in a garden (except for making hotbeds) till it is thoroughly decayed and all fermentation is gone off; as while it is in process of decay the gases it evolves are decidedly hurtful to plants. Those manures which abound in nitrogen, such as stable manure and the dung of birds, are the strongest and most dangerous; as if used incautiously they will blacken and shrivel up the leaves of the plants to which they are applied. Guano and pigeon's dung are very much alike in their properties, and both are of an extremely caustic nature; so that they should only be used in very small quantities, or be very much diluted. One ounce of guano to a gallon of water is a common proportion; or the guano may be mixed with six or seven times its own bulk of loam, peat, or charcoal, and dug into the ground before the crops are sown: if applied afterwards as a top dressing, it should be either in wet weather, or the soil should be well watered. Charcoal is very efficacious in some cases, but it appears variable in its action; as sometimes it produces scarcely any effect. Nitrate of soda and saltpetre act principally by supplying a particular kind of earth to plants that are in want of it, and of course will not suit all plants; but they are also of service in keeping the earth moist, and this, when not carried to an excess, is always useful.
When it is wished to keep plants constantly in a growing state, the soil should be rendered rich, and the plants should also be watered frequently, so as never to suffer the soil to become quite dry; equal care being taken to keep it free from stagnant water, which would rot the roots. When, however, the plant is to be hardened, to stay out the winter, it should be kept as dry as possible, and no manure should be applied for some time previously to the cold weather setting in. Nothing is less generally understood than the use of manures. They are in fact food; and should not be given to plants in excess, any more than children should be crammed with food. Starving and repletion should both be carefully avoided; and the great art of the cultivator is shown in supplying plants with food only when they need it. Too much water will sometimes produce leaves and stems instead of fruit and flowers; and shoots of great luxuriance very frequently do not ripen, and are killed by the first frost.
After telling you how to grow fruit, I must next tell you how to keep it. A proper fruit-room should be fitted up with broad shelves, or wooden trays with rims in front to prevent the fruit from falling off, and divided into compartments for the different kinds. There is generally a large table in the centre for sorting the fruits, and a thermometer should be hung on one side to regulate the temperature. According to Dr. Lindley, the essential points for a fruit-room are, "a low and steady temperature; dryness to a certain point, for apples are found to keep best in a rather damp atmosphere; and exclusion of the external air:" to this he adds, that it is necessary to keep the fruit in comparative darkness, to prevent it from becoming shriveled and ripe prematurely; that the temperature of the room should not be much above 40°; and that the shelves should be of white deal, as that wood does not give an unpleasant taste to the fruit.
Fruits keep best when laid separately, so as not to touch each other; and sometimes pears may be kept by packing them in fern, and grapes by packing them in jars in sawdust. Walnuts and chestnuts should be kept in rather a moist place, and covered with fern to exclude the air as much as possible, as they are much injured if they are kept too dry.
I may here mention that when sweet chestnuts are sent to the table, they ought always to be boiled first, and roasted afterwards; as, if roasted without previously boiling, it is scarcely possible to cook them sufficiently to make them wholesome, without burning them. After they have been boiled, before they are put down to roast, care must be taken to prick the skins; as, if this is neglected, the chestnuts will fly about in all directions as soon as the outer skin becomes parched.