What should I know about storing my homemade chili powder? I am planning on making some chili powder this weekend using ancho, pasilla, and guajillo peppers. I got a nice big bag of each recently and have some questions about chili powder. The second part of this question, about tweaking the preparation itself, is here.

The first concern I have is storage lifetime. I keep reading that it should stay potent for about 6 months, in an airtight container. I have also read that I can mill/blend the peppers and freeze the powder for 6 months and then use. How does storage work?


Do these 6 months stack on top of each other; or is it six months potency one way or the other? 
Is there an alternative preparation of/method for using the milled chili (powder) that would allow me to get a better shelf life? (My main concern is not having spices that last forever; rather it is to have them remain potent for a reasonable period.)
Does the "6 month potency" begin once the chili powder is prepared, milled, or when the peppers are dried (or some other time)?
From experience I'd say those 6 months don't stack. You could have 6 months in the jar, or 6 months in the freezer - very soon after defrosting the flavour would die out. If you have to freeze I would recommend using it straight from the freezer, if you can avoid it clumping.

The overall potency is degrading from the moment it's picked! But realistically from the moment of grinding, as the oils in the ingredient are slowly seeping and evaporating out of the grain.

Why not make smaller batches more regularly? That's what I do for garam masala, mixing a new batch every 3 months or so.

I would always recommend oven drying spices / peppers very low for a long time - say 2 - 3 hours at 100C (212F). Wet ingredients could be dried in the same way, else added at the time you are going to cook with them.