This section is from the book "Commercial Gardening Vol1", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
In the case of old trees, having the stems many times thicker than the scions, whip grafting could not be conveniently done. The stocks are headed back at the proper season, and at the proper time a slit is made in the bark with a strong-bladed knife, or a cleft is made with a chisel, as shown in fig. 77 at a. The latter is not a good way to graft, as it leaves a fissure open in the stem, in which water collects and rots the wood later on. The slit with the knife is best, and the bark may be gently opened outwards with the point of a small chisel or flat piece of steel to allow the graft, which has been cut obliquely to form a wedge, to be pushed in easily. Two or three similar grafts may be inserted in one stem if necessary, and if the bark only is open, without splitting the wood, the process is known as "rind" or "crown" grafting, as shown in fig. 78.
When the stock and scion are about equal in diameter this method may be adopted, but it is not so good as whip grafting and is also more troublesome to perform. As shown in fig. 79, the stock A is cut up on both sides to form a wedge ending at c. The graft or scion B, having several buds, is split up the centre, and each half is thinned to make it fit astride the tapering stock, and so that the inner bark of stock and scion are flush with each other at least on one side.
Fig. 77. - Cleft Grafting.
Triangular Notch Grafting.
Crown or Kind Grafting.
Fig. 78. - Forms of Grafting.
Fig. 79. - Saddle Grafting.
This is a form of whip grafting, but the stem is not cut away completely above the point of union. A notch or slit is made in the side of the stock, as shown in fig. 80 at a, 6, and the scions are inserted and tied. It will be noticed that horizontal or vertical shoots may be grafted in this way, and after the new shoot has grown to a good length the stocks may be cut off just above the point of union.
This is applicable to plants having non-woody stems, and is practised only for the sake of curiosity. Potatoes have been grafted on Tomatoes, and vice versa; Cauliflowers on Cabbages; Zonal Pelargoniums, Dahlias, etc. It seems, however, to be of real value in the Australian Glory Pea (Clianthus Dam-pieri), which grows freely when grafted on the stems of seedling Colutea arborescens, but will often perish on its own roots.
Coniferous trees have been grafted with young shoots in the forest of Fontainebleau and other places, the modus operandi, as described by Du Breuil, being as follows: "When the terminal shoot of the stock a (fig. 81) has attained about two-thirds of its length, it is cut back with a horizontal cut to the point where it begins to lose its herbaceous consistence and commences to become woody. The young leaves are cut off between a and d, a distance of between 2 1/2 and 3 in., leaving, however, about two pairs at the top d d, to attract the sap. Thus prepared, the stock is split down the middle to the depth of 1 in. or 1 1/2 in. The scion b is cut wedge-shaped, and introduced into the split, so that the commencement of the cuts on each side of the scion may be nearly 1 in. below the top of the stock. The scion should be cut at the place where its consistence is similar to the part of the stock where it is to be inserted. Its diameter ought to be as nearly as possible equal to that of the stock. The graft being placed, it is secured with coarse worsted, commencing the tying at the top and winding it down to the lower part. In the case of delicate species it is well to wrap paper round the grafted part as a protection against the drying action of the sun and air. The shoots at c are then broken at about 1/2 in. from their bases. Five or six weeks after grafting, the cuts will be completely healed; the tie may then be removed, and the two portions d furnished with leaves at the top of the stock should be cut off, otherwise they might give rise to buds, which, in pushing, would weaken the graft".
Fig. 80. - Side Grafting.
Fig. 81. - Herbaceous Grafting - Coniferous Trees.