Grafting is a technique where a section of a stem with some leaf buds is attached to the stock of an existing tree. Grafting is not an anyhow process. It's a technical process which must follow the rule for survival. The shoot is cut in a way that it fits into specific spot on the existing plant so that the transport vessel of both pieces line up. In this way, the grafted piece can continue to grow as it get nutrients and water from the stock plant