Grafting is a process which fuses plant material from two different plants. There are a number of reasons to perform a graft, ranging from cosmetic to practical. Viticulture, raising grapes for wine making, is a field in which grafting is commonly used, and many fruit trees are also grafted. It is relatively easy to graft successfully, although the procedure does take some practice.
Gardeners have been grafting since at least the Roman era, and the procedure has remained much the same throughout history. When a graft takes successfully, two separate plants appear to be growing as one unit. Often, the grafting seam is close to invisible, except for someone with a great deal of horticulture experience. Grafting is extremely useful for plants and gardeners alike, which is why the practice has endured for so long.
The plant material being grafted to a parent plant is known as a scion or slip. It is usually a small cutting with a few buds. The parent plant is called the stock or rootstock, since often the graft is placed just above the roots. To make a graft, the scion and rootstock are both cut, and then attached to each other. Commonly, the scion is wedged into the stock. The graft is waxed or taped to keep it moist and promote growth, and when the graft takes, the protective layer is removed. Typically, grafting is performed when both trees are dormant, to reduce shock and to promote fusing when the stock and scion both start to grow.
One of the most common reasons for grafting is the propagation of hybrids. Many hybrids, fruit trees especially, will not breed true. In other words, the seeds of a hybrid fruit tree will produce fruit trees, but the fruit trees will not resemble the parent. To reproduce the hybrid, grafting on sturdy stock is performed, usually on the trunk just above the roots, leading the tree to produce the desired hybrid fruit.
In other cases, grafting is performed to make a plant more healthy. For example, the roots of an established plant which is accustomed to an environment may be used as stock for a new cultivar. In the wine industry, grafts of Old World grape varieties are often placed onto New World stock, since the roots of Old World grapes are susceptible to infection and rot.
In a small garden, grafting can allow a gardener to grow several types of fruit on one tree, or to grow a fruit tree which is self pollinating. This can also be done for decorative reasons. For example, a grafted fruit tree may produce flowers of different colors on different branches, if the graft is placed onto a branch rather than the trunk.