Scions of desirable varieties must be grafted onto a compatible rootstock; otherwise, the graft will eventually be rejected by the host tree.

The rootstock determines the tree’s size, vigour, and adaptability to soil conditions, while the scion dictates the type and timing of flowers and fruit.

In most cases, grafting is only successful between closely related species—for example, apples must be grafted onto other apples. However, there are exceptions, such as grafting almonds onto peach rootstock.