A packing method and unit for folding a blank on a packing machine; a first suction pickup head engages a first panel of the blank inside a store; a second suction pickup head engages a second panel of the blank inside the store; the pickup heads are moved from a withdrawal position at the store to a release position at a packing conveyor, insert the blank inside a pocket on the packing conveyor; and the blank, folded into a ‘U’, is released inside the pocket on the packing conveyor; as the pickup heads are moved from the withdrawal position to the release position, a relative movement between the first pickup head and the second pickup head is produced to fold the blank into a ‘U’ before the blank is inserted into the pocket on the packing conveyor.