Grafting is a way in which trees are reproduced by trying to merge a severed shoot, called a scion, with roots of previously grown plants, known as rootstock. This is done in order to ensure that newly grown plants have the same characteristics the plant from which they were cut and so that very well established root systems can continue to be used. This practice is used very extensively in agriculture, with some plants almost exclusively being propagated through grafting.
Grafting is done during winter and early spring when the scion and rootstock are dormant. For plants kept in containers, they are sometimes placed in winterized houses in order to encourage dormancy. The grafting process for container plants is often conducted indoors and is usually called bench grafting.
Scions are collected by cutting shoots with very clean cutting tools such as shears or knives. The scions are then placed in burlap bags with moisture. Tools are sterilized with fire or with a sterilizing solution. One part bleach and nine parts water can be used to sterilize scions, which are simply soaked in the solution. Scion wood is usually collected that does not have any pests or diseases, since these issues can be transferred to the next tree grown through grafting.
When cutting a large number of scions, they are usually cut to the same length and are bundled together. They are usually stored in moistened burlap or sphagnum and are iced or refrigerated in order to keep them dormant until it is warm enough for them to be grafted. They must never be frozen.
Several techniques are used to graft the scion to the rootstock. One method is to split the trunk of the rootstock halfway so that two scions can be inserted into the split. Then, wax is used to seal the scions into the crack where the rootstock is split. Another method is to cut a flap open on the sides of the trunk and to insert the scions into the flaps, sealing with wax again. For thinner rootstock, the rootstock can be cut diagonally and the scion can also be cut at the same angle. Then, the scion is placed on top of the root stock and tied to the root stock with rope.
Farmers usually choose rootstock based on how healthy the soil is around the rootstock and how well the previous tree did with the rootstock. However, gardeners might not have as much of a luxury, since they generally have less plants then a farmer and therefore have less rootstock to choose from. Grafting might be a bad idea for gardeners who have unsuccessful rootstock and many gardeners choose to rip up and destroy previous rootstock in order to plant new plants that might develop better rootstock.