Grafting, an asexual means of propagation, occurs when two different plant parts are joined together and encouraged to grow as one. Horticulturists graft a variety of compatible plants, trees and shrubs. Although slightly difficult to perform, a thorough understanding of the basics involved and plenty of practice yields successful results.
Scion is a piece of shoot of twig detached from a tree or plant. It forms the upper part of the grafted plant that produces fruit, leaves or flowers. It should ideally be 6 to 8 inches long with 1/4- to 3/8-inch diameter. Select scion wood from a healthy, disease-free plant that is at least a year old. Make sure the scion has at least three buds on it that will eventually develop into leaves and prepare food. Collect scion wood during the winter, when the plant is dormant. Place it in a plastic bag filled with moist saw dust and refrigerate for up to 90 days or until spring, which is the best time to graft. Mist the saw dust frequently while it is refrigerated so it is evenly moist.
Rootstock, understock or simply stock forms the root system and ultimately the foundation of the grafted plant. It is imperative that the scion and rootstock are compatible--that is, belonging to the same genus and species--so the graft's union heals and grows as one plant. Make sure the rootstock is healthy and disease free.
The main objective of grafting is to obtain maximum cambium (nutrient-dense layer under the bark) to cambium contact between the scion and stock. The exposed surface is comprised of a thin layer of cells, which is why maximum contact is essential. For this purpose, always use a sharp, clean knife so you make straight, uninterrupted cuts instead of jagged ones. Make sure the cuts on the scion and rootstock match (equal in size) for maximum cambium contact. In some cases you can join several scions with smaller diameters to the larger stock. Once the cut on the rootstock is made, quickly position the cut section of the scion over it and press tightly. This point where both meet is the "union." Wind rubber budding or grafting tape over the union to protect it and encourage it to heal. It will naturally decay after the scion begins to grow.
Always use a clean knife during the process. Dip it in alcohol solution beforehand to kill any possible germs. Mist the scion frequently so it does not dry out until the union heals, which usually takes up to two weeks. Reduce moisture once the graft heals.