Gardner is an unincorporated community and a U.S. Post Office in Huerfano County, Colorado, United States. The Gardner Post Office has the ZIP Code 81040.A post office called Gardner has been in operation since 1871. The community has the name of Herbert Gardner, a local pioneer. Herbert was the son of Henry Gardner.Gardner is located at 3747?01?N 10509?57?W? / ?37.78361N 105.16583W? / 37.78361; -105.16583.Just to the east of Gardner is the Gardner Butte, a volcanic plug that rises conspicuously from the surrounding plains.