A post mount guide includes a tubular body having a throughhole for non-frictionally freely slidably receiving therethrough an upright support portion of a post mount, at least one pair of mounting panels having each panel positioned 90.degree. from the other and adjacent to one another, the panels extending spaced apart from and connected at one end to the tubular body, wherein the mounting panels of each pair of panels are adapted to resiliently bend and configured to receive and retain a fastener therethrough, and a stop mechanism is included with each pair of panels for stopping the panels from bending beyond a fixed position toward the tubular body. The stop mechanism includes first and second end portions of the adjacent mounting panels, respectively, being configured for reversible abutting engagement with one another upon bending inward to the fixed position toward the tubular body.