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The effect of light and temperature on the germination of Mammillaria mazatlanensis, Stenocereus alamosensis and S. thurberi subsp. thurberi, three cacti species inhabiting the northwestern coast of Mexico, was assesed. The germination response after 21 days in incubation and the mean germination time (t(50)) were subjected to a Kruskal-Wallis analysis of variance and were compared with the Wilcoxon test at 5%. The three species germinated better under constant light with controlled shading (90644 than in darkness (<5%), indicating that seeds are positive photoblastic. The heat treatments (t(1): control at constant temperature of 30 degrees C, t(2): fluctuating temperaturse of 30-38 degrees C, and t(3): 60 degrees C for 11.25 days presowing) did not have any effect on the germination of S. alamosensis and S. thurberi subsp. thurberi, but increased the germination of M. mazatlanensis in similar to 10% compared with the control. The surface rocks provide appropriate conditions of light and temperature (30-38 degrees C) during the summer, and attenuate the water stress in the coastal desert of Sinaloa, favoring in these microsites the seed germination of the three cacti studied.