Graft: grafting. Strictly speaking, a graft is part of a young branch belonging to a new shoot of the current season’s growth, which is removed from a tree one wishes to propagate in order to be inserted into another tree serving as a rootstock, of which one wishes to improve the fruit or modify the species. But the word is more commonly applied to the act of grafting itself or to the product of this operation, and it is in this last sense that it has been claimed that grafting constitutes the triumph of art over nature. By this means, nature is indeed obliged to readjust, follow other paths, become modified, and substitute the good and true for the abject. Lastly, by grafting one can modify the sex, species, and even genus of trees relative to the methods of botanists, whose systems do not always concur with the results of grafting. [1] This humble art has been most ingeniously contrived for the perfection of that part of agriculture to which it is applied, essentially to all fruit trees. Grafting improves the quality, colour, and size of fruit, and helps it to ripen earlier. It enables trees to bear more fruit and in several cases it alters the natural volume of a tree. However, it cannot create new species: Nature may bow to one or two constraints, but she will not stand to be imitated. Here, we are concerned only with improving, embellishing, and multiplying her productions, and it is only by sowing seeds and following Nature’s dictates that new varieties or species can be obtained. Even then one must leave everything to chance, and light upon upon rare and remarkable circumstances.

We shall refrain from discussing the compatibility of different trees and rootstocks because this information will be given in the article pertaining to each tree. We will instead proceed to explain the various methods of grafting, which are cleft grafting, crown grafting, chisel grafting, flute grafting, approach grafting, and shield grafting.

Cleft grafting: this is the oldest mode of grafting and is used primarily on ‘pip-fruit’ trees. It may be applied to rootstocks with a diameter of 1-6 inches: a small size generally stands a better chance of success, though this method has been known to work on rootstocks with a girth of three feet into which grafts of a diameter of 1½ inches were inserted. However, when trees are this broad it is better to graft on to their medium-sized branches. This type of grafting is best effectuated from the beginning of February to the time when the sap is rising sufficiently for the buds to open or the bark to become detached. Rain, dry wind, and direct sunlight should be avoided. The grafts should be selected from trees which are sturdy and yield well, and from new healthy shoots which are about to fruit, not from gourmands or branches of ‘false’ wood, which are wholly unsuitable for grafting. One may make a store of good branches and cut them before they are needed, in which case they should be left intact and half covered with earth in a cool, shady place, where they may be kept for one or two months. They will thrive better for being stored in this manner: deprived of nutritive sap, they just manage to sustain themselves by means of the soil’s humidity, but they recover rapidly as soon as they are grafted on to sturdy rootstocks, from which they receive a nutritive sap more analogous to the first. Moreover, by this means the grafting period is extended, because these branches feel the warmth which causes the sap to rise in spring much later.

This mode of grafting requires more implements than any other: a saw to cut the stem of the rootstock, a grafting knife to half open the cleft, a strong knife with a five or six inch blade to split the stem, an ordinary pruning knife to prune the graft and smooth the bark of the trunk after the sawing, a wedge made from iron or hard wood, and a hammer to drive in firstly the knife which half opens the cleft, and then the wedge which opens the cleft and keeps it open. One should also have some rich, manageable soil, pieces of bark, moss, and osiers.

One proceeds as follows: a graft of two or three inches is cut so that it has three or four good buds. A section in the form of a wedge is cut through two sides of the broad end of the graft half an inch along its length, taking care to preserve the bark, which ought to be firmly attached, on the other two sides of the graft. The side which is to be turned outwards should be somewhat broader than the inward side, and on this outward side, immediately above the cut, the graft should have a good bud. One should then saw the stem of the rootstock at a greater or lesser height according to whether one intends it to form an espalier, half-standard, or standard tree. The sawing should be done at a slight incline, both for drainage and to facilitate the union of the barks. It is then advisable to smooth down and clean the rip made by the saw to the bark of the rootstock, using a pruning knife. The pruning knife is then placed transversely at the centre of the stem, and a few light hammer blows are struck on to the knife to begin the cleft and open an entrance for the wedge, which is struck with the hammer until it has made a place for the graft. If the cleft has left some rough edges, either on the wood or bark, they should be smoothed with the pruning knife so that the graft may be well gripped and secured, without any remaining apertures or imperfections. These preparations having been made, the graft is inserted, being careful to make the bark of the graft correspond to that of the rootstock, which is crucial to the success of the operation.

We stated above that the bark should remain on two sides of the graft when it has been cut, and that one of these two sides should be broader than the other: it is this broader side which should face outwards, and the bark of this outward side should correspond to that of the rootstock so closely that sap may pass from one to the other without obstruction or deviation, as though the two barks were one. They need to correspond this closely because experiment has shown that the wood of the graft never merges with that of the rootstock: the union takes place uniquely between the two barks and the ligneous parts merge only as new wood is formed.

When the grafting has been completed, the clefts and cut sections are coated with a sealant made from wax and resin in order to protect the graft from rain, drought, and other poor weather conditions which invariably impair the graft. However, those who are less fastidious simply place a piece of bark over the horizontal graft, cover the top of the stem with a mixture of moss or chopped hay and clay, and envelop the whole with linen, allowing the graft through. [2] The linen is attached at the bottom to a strong osier, which also tightens the cleft made to the rootstock.

It is possible to insert two grafts into the rootstock, or even four if it has a broad stem, by making a second cleft in the form of a cross, but usually only one graft is inserted.

Cleft grafting is now far less common than shield grafting, even though the first method enables a standard tree to grow more vigorously and rapidly than the second.

Crown grafting: the procedure for crown grafting is similar to that used for cleft grafting, except that the grafts are placed between the bark and the wood, without making a cleft. The grafts should be stronger (at least half an inch in diameter) and taller, and the cut sections should be longer. It is necessary for the sap to have risen in the tree which one wishes to crown so that the bark may separate easily from the wood. One or more branches are sawn at one or two feet above the stem of the rootstock, and the jagged edges left by the saw are cut and smoothed with a pruning knife, the point of which is then used to separate the bark from the wood so that the grafts may be inserted between them. Six or eight grafts can be inserted into each branch depending on its girth, following which the graft unions are covered up, as in cleft grafting. Crown grafting is used only for large ‘pip-fruit’ trees which would not easily withstand cleft grafting.

Chisel grafting: another mode of grafting which is similar to cleft grafting and is used only on large trees which might not withstand the latter. This is how to proceed: a fairly deep notch is made with a joiner’s chisel in the bark and wood of a medium-sized, vigorous, and healthy branch belonging to a tree one wishes to modify. The graft is inserted in a manner similar to the cleft-graft, except that the broad end of the graft should be pruned and adjusted so that it fills the notch made in the branch exactly. The graft is entered somewhat obliquely and so that the barks fit together well. It is tied with osier and covered with grafting wax or clay in more or less the same way as the cleft-graft. To be more certain of success, several grafts may be inserted into a single branch. The correct time for this method of grafting is from the beginning of February until the rising sap causes the bark to separate from the stem.

Flute grafting: this is the most difficult method of grafting. It is carried out in May, when the sap has risen in the trees. Two branches are selected, one on the rootstock and one on the good species of tree one wishes to propagate. These two branches should be of the same breadth at the parts at which they are to be joined. The branch of the rootstock is left on the stem: only the end is cut three or four inches above the intended point of the graft union. After having made a ringed incision underneath, all of the bark is removed along this three or four- inch length. The good branch is then detached from the tree and the end is cut above the area deemed to be of a suitable breadth. A ringed incision is made in the bark of this scion to produce a tube about two or three digits wide, furnished with two good buds. [3] The tube is removed skilfully by pressing and turning the bark with one’s fingers, taking care not to damage the buds. It is then slipped on to the barked wood of the rootstock branch so that it covers the wood and joins up with the bark remaining on the rootstock. If there is any roughness, it is smoothed with the pruning knife. Lastly, the top part of the graft is covered with grafting wax or clay, and, more commonly, small wood shavings are brought down on to the bark by cutting the upper end of the wood, which is still barked, all round with the pruning knife, thereby forming a type of crown protecting the graft from the air.

This method of grafting is rarely used, except on trees such as chestnuts, figs, olives, walnuts, etc. which would be difficult to graft by other means.

Approach grafting: this method can be used only on two neighbouring trees, unless one tree is boxed and can be approached to the other. It is undertaken towards the end of May, when the sap has risen in the trees. A single stem of at least a finger’s breadth is topped and left on the rootstock. At the upper part of the topped stem, a slanting section is cut deep enough to receive the healthy branch reduced to half of its breadth. This healthy branch is thinned at the sides and bottom so that it can enter the cut section and fill it exactly, with the two barks touching and matching on all sides. The openings are then covered with grafting wax or clay, and the graft is adjusted and tied in the same way as for cleft grafting. If after two or three months, when the graft union is examined, the barks have grown together sufficiently, the healthy branch is cut below the graft union and the covering is left for a while longer. This method of grafting does not readily succeed and is used only for a few exotic or collector’s shrubs.

Shield budding: this is the quickest and simplest method of grafting, and is also the most widespread, natural, and reliable. A gardener can make 300 shield-buds a day, whereas he would find it difficult to make 100 cleft-grafts, even though cleft grafting is the second quickest method. Young people may even be employed for shield budding and can be rapidly trained for the job. Nearly every tree can be shield budded: it is hazardous to graft a stone-fruit tree by any other method, and shield budding is the most suitable mode of grafting for exotic and collector’s trees. It requires only the simplest of implements: a grafting knife and some tow is all that is required. Shield budding succeeds more frequently than any other method of grafting, particularly in view of the fact that it can be repeated several times while the sap is still flowing should the first operation fail, which may be established in less than a fortnight. It is the most natural method, because it closely imitates the workings of nature: the mere substitution of a bud on a branch is sufficient; it is as if nature were being deceived. [4] Moreover, this form of grafting has prevailed so well that scarcely any other method is now used, especially given that shield budding never damages the rootstock: twenty unsuccessful incisions will leave a branch healthy and intact; the bark will easily cover over a few wounds inflicted on its surface and one can start afresh the following year. [5] Lastly, shield- budded trees bear flowers and fruit earlier than cleft-grafted trees.

Shield budding can be undertaken during the summer months, from the beginning of May to the end of September, except during periods of rainfall, excessive heat, or drought. The combination of the two following circumstances is also required: the sap must have risen both in the rootstock and in the tree from which the bud is taken. Shield-buds made at different times during the summer months do not make the same progress: those which are made before Midsummer Day grow in the same year and are called shot buds. Those which are grafted after 24 June are called dormant buds, because they grow only in spring of the following year. In each case, the shield budding is effectuated in the same manner.

Strictly speaking, a shield-bud is simply a latent bud which is lifted from a branch of the current season’s growth. To this end, one of the first branches of the season, the buds of which are well formed and nourished, is selected from a tree one wishes to propagate. One should begin by stripping the leaves down to the petioles in order to minimize sap dispersion and loss of water to the bud. The branch may be conserved for two or three days if necessary by keeping the broad end in a little water, or sticking it into the ground in a cool shady place.

In order to lift the bud from the branch, three triangular incisions are made in the surrounding bark with the grafting knife: the first incision is made crosswise two or three lines above the bud, the second incision is made at the side of the bud moving downwards in a curve and terminating below the bud, and the third incision comes down at the other side so that it crosses the second at about half an inch below the bud. These three incisions together form a downward-pointing triangle. [6] By pressing and pulling this section of bark skilfully without damaging the bud, it may be detached easily if there is sufficient sap.

The shield-bud having been lifted, it is then held between one’s lips by the petiole of a leaf which has been left on the branch for this purpose. A smooth surface is chosen on the rootstock and two incisions are made in it with the grafting knife in the shape of a capital T, which should be large enough to accommodate the shield-bud one intends to place there. [7] The bark of the two re-entrant angles is detached using the shaft of the grafting knife, and the shield-bud is inserted between these two sections of bark beginning with the point, which is gradually lowered until the top of the shield-bud corresponds exactly to the upper bark of the rootstock. Hempen tow, or where possible woollen thread, is then wound round several times without covering the bud and tied with a knot, in order to secure the barks and facilitate their union.

When this graft has been made with a shot bud, that is, before Midsummer Day, as soon as one notices, after about eight or ten days, that the bud is active and ready to grow, the rootstock is headed back to four digits above the shield-bud, so that by directing the sap to the new bud it will grow more rapidly and vigorously. [8] The bud-tying material is then either gradually loosened or cut behind the shield-bud depending on its progress. If the graft has been carried out using a dormant bud, that is, after 24 June, the bud is not freed or the rootstock headed back before the following spring, when the bud begins to grow.

There are other methods of grafting, such as root grafting, whip grafting, and inlay grafting, but the uncertainty of their success has caused them to be neglected. [9]

Grafting has been used primarily to propagate good species of fruit trees, since the seeds rarely come true. Moreover, it is generally accepted that grafting helps to perfect fruit by diverting the sap, obliging it to follow the detours and folds which always form at the graft union. However, grafting cannot change the species of a tree, or even create new varieties: this is nature’s prerogative. Grafting simply enables fruit to reach a certain degree of perfection. It is also used to propagate several collector’s shrubs and even a few trees, such as maples, elms, mulberries, etc., though grafting is detrimental to the shape, strength, and durability of these trees, which never regain their natural beauty and height.

We no longer admit the fantastic powers accorded to grafting by the ancients who studied agriculture and by a good number of moderns. If they were to be believed, grafting could produce the most amazing metamorphoses and change the fundamental nature of things, causing vines to produce oil instead of wine, forest trees to bear exquisite fruit rather than dry seeds, and planes to turn into fruit trees bearing figs, cherries, or apples. However, I have ascertained by a number of experiments that of all trees the plane is perhaps the least suited to being used as a rootstock: not only do the fruit trees I have just mentioned fail to take again, but a single shield-bud from a fig will also cause the rootstock to perish, and, even more surprisingly, shield-buds which were taken from and grafted on to the same plane were reluctant to thrive, even though the experiment was repeated several times. The changes wrought by grafting are more limited than one may think: the rootstock must be compatible with the graft, which cannot always be clearly established by the resemblance of the flowers and fruit, though this resemblance is still the best means of predicting the success of the graft. See the plates on Gardening. [10]

Notes

1. Pitton de Tournefort established the genus as a central unit of classification at the beginning of the eighteenth century and referred to the basic kinds belonging to each genus as species (Huxley et al., 1992, i.xlix-1).

2. The grafting clay described here approximates more closely to pug than to the French and Dutch ‘Onguent de Saint Fiacre’ or Saint Fiacre’s Ointment (Saint Fiacre being the patron saint of gardening), which was made from fresh loam and cow manure. Pug, which was common until the early nineteenth century, was composed of clay, horse manure, and chopped hay. The article shows that it gradually gave way to other sealants based on wax, resin, etc. (Huxley et al., 1992, iv.641).

3. The tube is the ‘flute’. This form of grafting is also called ‘greffe en anneau’ or ‘ring grafting’.

4. Approach grafting is thought to emulate natural grafting most closely (Huxley et al., 1992, iv.632).

5. See article To Cover over again.

6. This is the ‘écusson’ or ‘shield’ of the shield-bud.

7. Hence the alternative name for shield budding, ‘T budding’.

8. Four digits is about 7½ cm or three inches. This length of stem is called the ‘chicot’, or snag. See article ‘Chicot’.

9. Artificial grafting was advanced by the eighteenth century, and different modes were used to overcome specific obstacles (Huxley et al., 1992, i.632).

10. Grafting is not illustrated in the plates.