In central North Carolina potatoes can be planted as early as mid February and should be in the ground by the end of March. Potatoes planted later than March 31 will still grow, though their yields will likely be lower than earlier planted crops because they will not have as much time to form tubers before the vines start to wither in the summer heat. When and Where to Plant Potatoes. Potatoes planted in March will be ready to harvest in June and July.