how long to cook a crock pot roast on high
up vote 1 down vote favorite. My pot roast recipe says to cook on high for 6-8 hours or low for 3-4 hours. However, the instructions for my new Crockpot say that the low setting is just for warming, and should never be used for cooking.Many recipes I've found online do give instructions for cooking on low.y pot roast recipe says to cook on high for 6-8 hours or low for 3-4 hours.