I have a mixture that I created of almonds and walnuts mixed together and I'm wondering how long they will stay good if left outside in a canister on the counter?
i don't know, but you'll know when they're bad. the oils turn rancid and you will smell it.
It takes a while for them to go bad.
keep them in the freezer... they thaw in about 5 minutes... and no worry about going rancid. I keep all nuts in the freezer - it's easy to use little amounts.