The key here is LOW AND SLOW! While you may be tempted to jack the oven up to 350°F, be patient! 275°F is the perfect temperature without having to cook the pot roast alllllll day! Cooking at a lower temperature will allow the roast to get nice and tender, without drying out. At 275°F, a 3-4 lb. roast will take about 3 1/2 to 4 1/2 hours for it to shred easily and fall apart.