Prune your peach trees in May, once they have leafed out, but don’t prune off all the new wood that grew last summer. Peach trees fruit on that last season growth. Trim any dead or winterkilled branches and leave most of the new wood. Occasionally you can make a few bold cuts back to a vigorous branch closer
to the trunk if your tree becomes too leggy. As the tree matures, you may want to thin out the branches quite aggressively.