In this video on grafting citrus trees, learn how to graft citrus trees with budwood of larger diameter than the rootstock. The demonstrated technique, the Z grafting technique, is especially helpful in this situation.
I have used Z grafting with success to graft new trees and also to add new varieties to existing trees to make multi-variety citrus cocktail trees.
Grafting or graftage is a horticultural technique whereby tissues of plants are joined so as to continue their growth together.
The upper part of the combined plant is called the scion while the lower part is called the rootstock. The success of this joining requires that the vascular tissue grow together and such joining is called inosculation.