Potatoes typically take between 70 to 120 days to grow after planting, depending on the variety and growing conditions. Early varieties mature faster, around 70 to 90 days, while main crop varieties like russets can take up to 120 days or more. Factors such as soil temperature, moisture, sunlight, and pest control also affect growth time. Potatoes start to sprout in about 2 to 6 weeks and go through stages of tuber formation and growth before they are ready to harvest, usually when the plant's foliage dies back.