The effect of soil temperature on the development of carrots (Daucus carota L.) was analysed under four conditions: with polyethylene cover over the crop and bare soil; without polyethylene cover over the crop and soil with mulch; with polyethylene cover over the crop and soil with mulch; and without polyethylene cover over the crop and bare soil. A close relationship between type of mulch, soil temperature, and root yields was observed. The treatment with plastic covering the crop and the soil with mulch had the greatest yield, and the treatment with neither plastic covering the crop nor mulch on the soil had the lowest yield.