Put everything except the parsley in the crockpot. Cover with enough water to come within about 2 inches of the top of the crockpot. Let everything soak for 30 minutes before turning on the crockpot.
Set to low heat and cook for a minimum of 6 hours and up to 24 hours. The longer you let it cook, the better it will be. About 10 minutes before taking it off the heat, add the parsley. When it's done, remove the bones and vegetables (there won't be any nutrients left in them anyway because they all went into the broth). Pour the broth through a fine mesh strainer and collect the broth in a large bowl. Use the broth immediately, or refrigerate it to use later.