Grafting involves the wounding of two growths and the arranging of them so they heal together. One of the two growths is called the stock, understock or rootstock. The host plant is rooted in the soil and provides nourishment for the other growth. The dependent top section is called the scion.
There are five benefits of grafting. First, it is used to propagate plants that cannot be conveniently or economically reproduced by other means. Second, grafting makes it possible to combine certain traits like disease resistance and plentiful fruits in one plant. Third, it can alter the appearance or behaviour of a plant, an example would be dwarfing a plant or making it bloom better. Fourth, it can be used to repair damaged plants and put new life in old stock. Lastly, it's possible to produce plant forms that otherwise would not exist.
Grafting - When 1+1 =1
Basic tree anatomy - definition of terms
I opted not to discuss soil conditioning, tools, etc. I would assume that you already have a garden and would like to get more out of it.
Before we start, let's get acquainted first with some basics. Let's begin with a basic anatomy of a tree.
Outer bark covers the plant, this is a layer of old, dead cells which serves as a protection for the living cells from rain, cold, wind, pests and diseases. When grafting or pruning, be careful not to let bark peel beyond the edge of the cut since this will expose the inner bark.
Inner bark lies next to the cambium layer and composed of young and active cells. The inner bark (phloem), carries sugars manufactured by the leaves and distributes them through the plant. When the outer bark is thin, sunlight induces chlorophyll to form in the inner bark, turning the bark green. During winter pruning, this green layer indicates that a branch is alive.
Cambium is were the cells divide increasing the plant's girth. When soil warms and sap rises from the roots, the cambium cells divide, inside and outside. The new inside cells become wood tissue, those on the outside become bark. In grafting, the cambium unites the graft.
The heart of a plant's anatomy is not at the heart of the plant but the cambium. Only one cell thick and invisible to the naked eye, from it comes all the plants other cells. If the cambium is severed everything beyond that point dies.
Sapwood is inside the cambium and carries water and nutrients from roots to leaves. Each year' growth becomes an annual ring, marked by denser tissue as the seasonal rate of growth slows. Vascular rays run laterally through this sapwood, carrying water and nutrients
Heartwood. As sapwood cells die, they harden into dark heartwood, providing the plant with a stiff internal support.