Carbohydrate is the most needed nutrient of mushroom mycelium growth. Foxtail millet flour has higher carbohydrate content that can be used as a substitute for potatoes in the manufacture of F0 mushrooms seed. Potato contains 19,10 g carbohydrate, while foxtail millet flour contains 68,32 g carbohydrate. The research aims to determine the growth of F0 oyster mushroom and straw mushroom seed with use foxtail millet flour as alternative media on different concentrations. This research use experimental method research with Completely Randomized Design (RAL) of factorial pattern, which consist of two factors are concentration of foxtail millet flour and type of mushroom. The analysis technique use qualitative descriptive data. Based on the results of the research, the best average of growth speed mycelium on J2T2 (Concentration of foxtail millet 15%, straw mushroom) with the diameter of mycelium is 3,1 cm and the density of mycelium is tight. Whereas the worst average of growth speed mycelium on J1T3 (Concentration of foxtail millet 20%, oyster mushroom) with has not mycelium growth
