A method for heating a preform (1) comprising a body portion (4) extending along a longitudinal axis (A1). The method comprises the following steps: introducing the preform (1) into a heating apparatus (5) comprising an array of infrared emitters (50) arranged in multiple columns (Cj) and rows (Ri); setting power levels of the infrared emitters (50) so as to divide said array into subsets of columns (SCn); andheating the preform while translating it in a direction parallel to the rows (Ri), and simultaneously rotating it around its longitudinal axis, the rotation and translation speeds, and the power levels of the infrared emitters (50) being set so that the power levels of the subsets of columns (SCn) facing zones (42) of the body portion extending longitudinally are different from the power levels of the subsets of columns facing the rest of the body portion, said zones extending relative to one another in a polygonal array.