The invention relates to a device designed for mixing and distributing, by means of tossing, sand used for weighing down synthetic grass, as well as aggregate used for improving the flexibility thereof. The device according to the invention is characterized in that it comprises, supported by a single frame (1) and coacting in series, at least one row of claws (2), the pressure of which can be preset, and which are intended for lifting the blades of grass, and at least one row of brushes (5, 6) for tossing the sand and the aggregate. The device is also characterized in that said frame comprises, for carrying out the tossing operation at the edges of the grounds, two lateral extensions (7), each including at least one row of claws (8), the pressure of which can be preset, and which are arranged obliquely and intended to lift the blades of grass, as well as at least one brush (11) that is also arranged obliquely.