If you eat an apple and plant the seed, you may well end up with an apple tree. However, the apples the tree produces likely won't taste like the apple from which the seed came and may not taste good at all. When reproducing fruit trees, then, horticulturalists need other cultivation methods besides planting a seed and hoping for the best. Grafting is one commonly used method of propagating fruit trees.
Grafting joins parts from at least two plants into a single plant. In most cases, grafting combines a budded branch of a desired type of tree onto the root system of a second type of tree. In addition to reproducing fruit trees, grafting provides horticulturalists with a means to add or change the type of fruit produced by a mature tree or combine multiple cultivars onto a single tree for cross-pollination purposes.
Grafting works because of a rapidly growing layer of tissue found beneath the bark called the cambium. The cambium produces the vascular tissue that conducts water and nutrients back and forth between the roots and leaves. If you establish contact between the cambium of two compatible tree species, the cambium will grow together. The grafted portion of the plant will be able to receive water from the roots, and the roots will be able to receive sugars produced in the leaves.
Different types of grafts meet different needs, particularly with respect to the size of the tree. Grafting a small twig onto a small rootstock demands a different method than grafting a twig onto a mature tree. Cleft grafting is a popular method that inserts new plant material into a split created in the rootstock. It can be used for large or small grafts. Whip grafting combines two equal-sized small pieces. Bark grafting inserts a small piece of stem beneath the bark of an actively growing tree. What all of these methods have in common is that they require contact between the cambium of the two plants.
When choosing to propagate through grafting, first establish whether the two plants are compatible. Closely related plants have a greater likelihood of compatibility, according to the University of Missouri Extension. Plants within the same species are generally compatible, and some plants within the same genus may also demonstrate compatibility. Plants in different genera only rarely graft successfully together.
Grafting is an advanced technique and won't work every time, even if you develop skill with it. If you decide to try grafting, exercise care and patience to ensure the greatest likelihood of success.