An apparatus for mowing grass, weeds or the like on an area of interest (S) by at least one first grass cutting step with a first working fluid (Fl) at a pressure of at least 250 bar. The apparatus is mountable on a vehicle (V) or the like susceptible to move along a forwarding direction (d) and is operable with a first feed line (2) of the first working fluid (Fl). In particular, the apparatus comprises at least one first spraying device (20) of the first working fluid (Fl) to the area of interest (S) including at least one first high pressure spraying nozzle (29) fluidically connectable with the at least one first feed line (2) and first means (10) for mounting the first spraying device (20) on the vehicle (V). The first nozzle (29) is movable mounted on the first spraying device (20) to rotate in a plane (π) or to oscillate along the same plane (π). Moreover, the first spraying nozzle (29) is mounted on the first spraying device (20) for spraying a jet of the first working fluid (Fl) in a substantially parallel direction or lying on said plane (π) or slightly inclined with respect to same plane (π) to transverse hit the grass, weeds, or the like, so as to cut the latter.
