Peaches fruit on one-year-old wood. Once a peach is harvested the section of branch on which it grew will never fruit again. Encourage new growth for replacement branches by pruning heavily every winter.
Peaches are twiggy trees, but the greatest number of flower buds form on sturdy new branches that made more than a foot of new growth the previous summer. Keep these and thin the more anemic twigs. You can head the strong new branches back by one-third to one-half if you want to keep the tree small. The tree will bloom on the remaining branches.
When peach and nectarine trees are large enough to bear fruit, the pruning objective is to encourage abundant growth of good fruit-bearing stems and to thin branches so light can penetrate throughout the tree. These trees bear flower buds on one-year-old terminal growth; the best shoots for fruit production are 6 to 18 inches long. Remove weaker or very vigorous shoots.
Begin in the dormant season by thinning back the primary branches to outward-growing laterals. To keep the center open, remove inward-growing shoots. Carefully thin small lateral branches along the entire length of each scaffold, leaving fruiting shoots that are the optimum length. Next remove diseased, damaged, downward-growing, rubbing, or crossing branches.
Maintain the tree height at 6 to 8 feet for easy harvesting. Cut upward-growing branches to strong outward-growing laterals, preferably by standing on the ground and using lopping shears or a pole pruner. Pruning from the ground helps keep the tree conveniently short.
Every year prune the scaffolds back to the same height to limit size and develop new fruiting wood. Since apical dominance is lost, several lateral stems will arise close to the pruning cuts. Retain some of the new growth for the following season’s fruiting wood and thin the lesser shoots. In future years make cuts to outward-growing laterals just above or below the previous years’ cuts.