You should certainly stock up to protect against a disaster, but meanwhile, here’s a website which will teach you how to start “square-foot” gardening now, so you can take care of yourself and yours now and post-disaster, See: http://www.squarefootgardening.com/ 
Note: this method will also provide work/food for everybody/anybody you find under your wing. And the “work” part: a feeling of being a contributor may be as important as the food. I heard the man lecture and this Saturday I will attend a workshop on constructing and completing a square-foot garden–but clearly it’s not rocket science. It is something everybody can start doing and thus feel they are participating in your preparation plans, even if they think that you are a bit of a fanatic.
BTW, I paid full price for the same book that he’ll sell you for 1/2 the price on the web site (Grrrrr!) – B.B.