China,I keep them in thick resealable poly bags from the shipper supply store. Much thicker than a zip lock. Aaand, I keep these bags in a wood cabinet in the shade, outside. Alternatively, I keep it in 5 gallon buckets.
I think it depends on your local weather.China,
Is there a particular reason you keep it stored outside? Does it stay outside year round?
I find that today’s cardboard boxes have a distinct formaldehyde odor that I hate and do not want to infuse into my tobacco during long term storage.What is the consensus on the humble cardboard box for long term storage? I like it so the residual moisture can leave. Plus they're free for the taking.