Old California peach trees need to be pruned once a year to ensure their health and encourage blooming and fruiting. Trimming is very important for old peach trees because it is the main method of getting new fruit and wood to grow. Un-pruned trees don't get the right amount of sunlight and air, which affects the branches and fruit production. Sunlight helps rev up the peach's natural sugars. Prune old California peach trees in the spring once there is no longer a chance of frost but before the fruit starts to grow. For best health, prune 40 percent of the peach tree annually.
Inspect the tree to see if there is flaky, peeling bark, which indicates dying branches. Old California peach trees will have branches that are no longer productive. Cut into a suspected dead branch. If it's brown as opposed to green, or hollow inside, you know it is dead. Prune the dead branches at the joint they share with healthy wood.
Trim branches that are damaged or bruised. Open wounds that show the pale green color inside can attract pest infestation such as the lesser peach leaf borer. The pests will attack healthy sections of the peach tree.
Remove branches that point up or down. They are not following the open-canopy shape that is best for peach trees. The unwanted wood will not grow healthy fruit and it will shade other branches from the sunlight they need to thrive.
Target branches on old California peach trees that rub each other or crisscross. They are clogging up the inside of the tree, limiting sunlight and air circulation.
Cut all unwanted wood back to where it meets another branch. Those with U-shaped connections are the strongest. Those that are connected with a V-shape are weaker and will likely not be able to withstand the weight of the peaches.
Prune in the dormant season because peaches need it to encourage new fruiting wood to grow and to keep that productive wood closer to the trunk.
Thin excess fruit from old California peach trees. Wait four to six weeks after blooming time and remove fruit that has holes or punctures from insects. Space the peaches 6 to 8 inches apart on each branch. This will make the remaining peaches sweeter and larger. It is especially important on older trees.
Pick up cuttings from the ground and move them to a compost pile. They may attract pests so you do not want the scraps near the old California peach tree.