Going thorugh my kitchen cabinets I noticed containers of flour. I have no idea how long they've been there. So I started wondering when does your flour sour. Thanks to Google I have a some answers..Turns out the lifespan of flour depends on what kind we're talking about. Refined flour (white flour ) will last a while...up to two years...but you have to store it in a cool dry place.Stored at room temperature white flour will last about a year.Store it in your fridge or freezer ..... should be good for a couple of years....To ensure a longer life for your flour put it into a covered airtight container....that also helps keep the bugs out.How to tell if your flours spoiled give it the old once over...look at it ...smell it...and check for bugs...If it has a sour smell or picks up flour weevils get rid of it immediatlyWhole wheat flour is an enterily differnt beast.....that needs to be stored in the refigerator..or even the freezer....But even then, it'll only stay good for a few months. Once it starts to smell like burnt rubber toss it out. Yeah no kidding. Another tip.....a bay leaf in the airtight jar...helps keep the little creepy things out. And you can recyle flour by putting into your compost.....Don't dump it all into the bin in one heavy layer...that cuts down on air flow...Sprinkle it evenly round the rest of leavin's. There you go ....and now you know....