The invention relates to a system for fixing an object in the ground, comprising at least one fixing peg (10) and means for carrying out the above. The peg (10) comprises a tube (14) and at least two lugs (28) on the lower end of a central support rod (24). An axial tension acting on the rod (24) which runs axially in the tube (14) and is fixed in rotation therein, causes the lugs (28) to deploy through openings (30) in the tube (14), such as to cause the extension thereof in the direction of tension at an angle to the length of the tube (14). An operating mechanism (33) comprises a threaded pin (36) with a screw (40) pressing on the head of the tube. The lower end of said threaded pin (36) is coupled to the upper end of the central support (24) in order to transmit an axial tension thereto on turning the screw (40) in a first direction.