The device comprises storage a hopper (2) in the base of which is seed distributor (4). The distributor comprises a disc notched in its periphery and rotated by a motor which also rotates an endless screw in the hopper opening. Between the hopper and the disc is a deflector (3) having an upper (30) and two side (31,32) walls enabling the seeds to be projected and directed downwards and to limit the spreading width.