Abstract: A machine for closing and sealing a plastic bag filled with material, such as, for instance, peat moss. The machine includes a carriage which moves around the top open end of the filled bag, hook-shaped fingers carried by the carriage, pivot down into the open mouth of the bag to catch the four corners of the same, oppositely disposed pusher fingers engage opposite walls of the bag, each intermediate a set of two hooking fingers to tension the bag wall horizontally. Then the hooking fingers gradually move down at an angle to converge in pairs at the two opposite sides of the bag mouth and, simultaneously, the pusher fingers continue to push intermediate wall portions inwardly to, all the time, maintain the bag mouth wall taut and to form opposite folds in the mouth, thereby closing the mouth.