by Kenny Popp

I am sure you have a tree that would be just perfect if it had a limb where there is not one. Pines and spruce are trees that have whorls of limbs that carry that immature look. With Inarching and Approach grafting, you can take and move or add limbs where you want them. In most cases you would be cutting this limb off anyway; so, if it fails, the scar will heal and maybe add character to the trunk.

The origins of grafting can be traced back to ancient times. There is evidence that the art of grafting was known to the Chinese at least as early as 1000 BC. Aristotle (384-322 BC) discussed grafting in his writings with considerable understanding. During the days of the Roman Empire grafting was very popular, and methods were precisely described in the writings of that era. Paul the Apostle, in his Epistle to the Romans, discussed grafting between the "good" and the "wild" olive trees (Romans 11:17-24).

The Renaissance period (1350-1600 AD) saw a renewed interest in grafting practices. Large numbers of new plants from foreign countries were imported into European gardens and maintained by grafting. By the sixteenth century the cleft and whip grafts were in widespread use in England, and it was realized that the cambium layers must be matched, although the nature of this tissue was then understood and appreciated. Propagators were handicapped by the lack of a good grafting wax; mixtures of wet clay and dung were used to cover the graft unions. In the seventeenth century many orchards were planted in England, the trees all being propagated by budding and grafting.

Early in the eighteenth century Stephen Hales, in his studies on the "circulation of sap" in plants, approach-grafted three trees and found that the center tree stayed alive even when severed from its roots. Duhamel, about the same time, studied wound healing and the uniting of woody grafts. The graft union at the time was considered to act as a type of filter, changing the composition of the sap flowing through it. Thouin in 1821 described 119 methods of grafting and discussed changes in growth habit resulting from grafting. Vochting in the late nineteenth century continued Duhamel's earlier work on the anatomy of the graft union.

Liberty Hyde Bailey in the Nursery, published in 1891, described and illustrated the methods of grafting and budding commonly used in the United States and Europe at that time. The methods used today differ very little from those described by Bailey.

We must first give some definitions:

Grafting is the art of connecting two pieces of living plant tissue together in such a manner that they will unite and subsequently grow and develop as one plant. As any technique that will accomplish this could be considered a method of grafting, it is not surprising that innumerable procedures for grafting are described in the literature on this subject. Through the years several distinct methods have been established that enable the propagator to cope with almost any grafting problem at hand.

Budding is similar to grafting except that the scion is reduced in size to contain one bud.

Scion is the short piece of detached shoot containing several dormant buds, which, when united with stock, comprises the upper portion of the graft and from which will grow the stem and branches, or both, of the grafted plant.

Stock is the lower portion of the graft, which develops into the root system of the grafted plant.

Cambium is a thin tissue of the plant located between the bark(phloem) and the wood(xylem). Its cells are meristematic; that is, they are capable of dividing and forming new cells. For a successful graft union, it is essential that the cambium of the scion be placed in close contact with the cambium of the stock.

Callus is a term applied to the mass of parenchyma cells that develops from and around wounded plant tissues. It occurs at the junction of a graft union, arising from the living cells of both scion and stock. The production and interlocking of these parenchyma cells constitute one of the important steps of the healing process of a successful graft.

Natural Grafting

One occasionally sees branches that have become grafted together naturally following a long period of being pressed together without disturbance. English ivy (Hedera helix) forms such grafts, and detailed studies have been made of translocation in natural grafts of this species. Not so obvious but of much greater significance and occurrence, particularly in stands of forest species, such as pine, hemlock, oak, and Douglas fir, is the natural grafting of roots.

Such grafts are most common between roots of the same tree or between roots of trees of the same species. Grafts between roots of trees of different species are rare. In the forest, living stumps sometimes occur, kept alive because their roots have become grafted to those of nearby intact, living trees. The anatomy of natural grafting of aerial roots has been studied; the initial contact is established by the formation and fusion of epidermal hairs. Such natural grafting permits transmission of fungi, viruses, and mycoplasms from infected trees to their neighbors. This can be important in closely set orchards and results in the slow spread of pathogens throughout the planting. Natural virus-free and virus-infected trees are grown in close proximity. In addition, fungal pathogens such as those causing oak wilt and Dutch elm disease can be spread by such natural root connections

Formation of the graft union

Briefly, the usual sequence of events in the healing of a graft union is as follows:

1. Freshly cut scion tissue capable of meristematic activity is brought into secure, intimate contact with similar freshly cut stock tissue in such a manner that the cambial regions of both are in close proximity. Temperature and humidity conditions must be such as to promote growth activity in the newly exposed and surrounding cells.
2. The outer exposed layers of cells in the cambial region of both scion and stock produce parenchyma cells that soon intermingle and interlock. This is called callus tissue.
3. Certain cells of this newly formed callus in line with the cambium layer of the intact scion and stock differentiate into new cambium cells.
4. These new cambium cells produce new vascular tissue, xylem toward the inside and phloem toward the outside, thus establishing vascular connection between the scion and stock, a requisite of a successful graft union.

Temperature conditions that will cause cell activity are necessary. Usually, temperatures from 55 to 90 degrees F., depending upon the species, are conductive to rapid growth. Outdoor grafting operations should thus take place at a time of year when such favorable temperatures can be expected and when the plant tissues, especially the cambium, are in a naturally active state. These conditions generally occur during the spring months. Temperature levels under greenhouse and bench grafting situations can, of course, be readily controlled thereby permitting greater reliability of results.

The new callus tissue arising from the cambial region is composed of thin-walled, turgid cells, which can easily become desiccated and die. It is important for the production of these parenchyma cells that the air moisture around the graft union be kept at a high level. This explains the necessity of thoroughly waxing the graft union or placing root grafts in a moist medium to maintain a high degree of tissue hydration.

It is important, too, that the region of the graft union be kept as free as possible from pathogenic organisms. The thin-walled parenchyma cells, under relatively high humidity and temperature conditions, provide a favorable medium for growth of fungi and bacteria, which are exceedingly detrimental to the successful healing of the union. Prompt waxing of the graft union helps prevent such infection.

It is essential that the two original graft components be held together firmly by some means, such as wrapping, tying, or nailing, or (better yet), by wedging (as in the cleft or notch grafts) so that the parts will not move about and dislodge the interlocking parenchyma cells after proliferation has begun.

The statement is often made that for successful grafting the cambium layers of stock and scion must be "matched.". Although this is desirable, it is unlikely that complete matching of the two cambium layers is, or ever can be, attained.. In fact, it is only necessary that the cambial regions be close enough together so that the parenchyma cells from both stock and scion produced in this region can become interlocked. A slight crossing of the stock and scion cambium layers insures callus interlocking. It is in the region of the cambium that the essential callus production is the highest. Two badly matched cambial layers may delay union or, if extremely mismatched, prevent the graft union from taking place. In studies of grafting monocotyledonous plants, it was found that a cambium layer is not necessarily required for a successful graft union but that any meristematic tissue would generate callus tissue to lead to the formation of a union between stock and scion.

Some plants are more difficult to graft than others, even when no incompatibility is involved. Difficult ones, for example, are the Hickories, Oaks, and Beeches. Nevertheless, such plants, once successfully grafted, grow very well with a perfect graft union.

Some species are so difficult to propagate by usual grafting or budding methods that "Approach grafting", in which both partners of the graft are maintained for a time on their own roots.

"Inarching and Approach grafting is an interesting technique that has many applications for Bonsai use. It is also reasonably easy to do as all parts remain on their own roots until the graft is successful. Inarching occurs in nature frequently as trees or branches growing very close together eventually merge. It takes about one year for conifers to graft properly; however, deciduous varieties are often quicker. Following are some ways Inarching may be used for Bonsai.

1. A branch from a tree can be repositioned on the same tree. See figure 1 & 2. Using this technique, the position of a branch may be improved or foliage brought closer to the trunk. Slice off similar shapes from the branch and trunk, and tie together securely.
2. A branch may be inserted through a hole drilled through the trunk, then bark cut off so that the limb is a snug fit, and the wound waxed for moisture retention. See figure 3.

Approach Grafting;

1. A branch from another tree may be grafted to shorten the trunk or simply to produce lower branches. See figure 4 and 5.
2. Many trees may be grafted together to produce a thicker trunk and more branches. The trees may be spiraled or plaited. After they graft together it will appear as a gnarled, aged trunk, while the twisted trunk may appear to have been sculpted and twisted around by many years of exposure to the wind and other elements of nature. A multiple trunk style can also be produced this way.

If you wish to thicken a trunk at the base to produce a better taper, the best way is to allow a lower branch to grow without trimming for a while. A temporary use of grafting is that if a tree does not shoot from old wood, a branch may be grafted at the back and low down on the trunk. It is then left on, without trimming, until sufficient thickening has taken place in the lower trunk region. The branch is then removed and, having been grafted at the back, no unsightly scar is visible." Bonsai-Its Art,Science,History and Philosophy-Deborah Koreshoff