The invention relates to a mold for a container that includes a mold base. The mold base includes a peripheral face, a central dome, and a central well formed in the dome and extending along a frustoconical sidewall from a top edge of the dome having a top diameter, to a bottom having a bottom diameter smaller than the top diameter. The mold also includes a stretching rod that ends with a hemispherical distal end having a radius, the value of which is between that of the bottom radius and that of the top radius of the central well. When the rod is in the bottom position, it is separated from the sidewall of the central well by a distance smaller than the distance that separates it from the bottom of the well.