Pecan trees, also called Carya illinoinensis, grow 65 to 130 feet tall and produce oblong nuts popular in cooking. They are the most recent fruit tree to undergo cultivation, and they grow best in USDA zones 5 to 9. This means they will survive the winter where temperatures do not drop below -10 degrees F. To produce the best harvest, you must know how to prune this plant properly--especially when it is young.
Sterilize your pruning shears before you use them by rubbing them down with rubbing alcohol and a rag. This will prevent the spread of diseases to your pecan tree.
Cut off the top 1/3 to 1/2 of the tree. This is called heading back. It will encourage the roots and the branches to grow evenly.
Choose a vigorous straight shoot for a central leader. Cut out all other adjacent upright shoots in late winter. This will allow more energy to go into nut production later.
Choose scaffold branches for the tree as it gets older. Ideally, these branches should be 18 inches apart vertically and positioned on all sides of the tree. Cut off any branches that are too close together, clipping right outside the branch collar.
Prune mature pecan trees only when necessary and only in late winter when the tree is dormant. If narrow or Y angles develop, prune off one of the shoots as soon as you see the problem. If left alone, they may split off the tree. Also cut off branches that are rubbing, as well as dead, diseased or broken branches.