The aim of this work was to study the influence of substrates in sowing of Mimosa caesalpiniaefolia Benth. The experiment was conducted in the Agricultural Research Center of Temperate Climate (CPACT) - EMBRAPA and Laboratory of Vegetable Physiology, RS, Pelotas, Brazil. In a growth chamber at 25°C of temperature were compared substrates of sand, soil and rice saw with seeds sowed at 1,0, 2,0 and 3,0cm, in black polyettylene bags of 8 x 18cm. The percentage of emergence, emergence speed index, stem and root light, fresh and dry weight matter of stem and root were avaliated. Besides, the electric conductivity and the imbibition curve were determined. Data were analysed statistically using a completely rondomized factorial design 3 x 3 with 4 repetitions of 25 seeds. The treatments of substrates and sowing depth presented significative differences. The sand showed the best response, followed by the soil and rice saw, and sowing at 1,0 and 2,0cm of depth were superior at the 3,0cm.