In winter, no need to tend them daily,either. So you can have twice as many, if need be. If one area becomes non-productive, it aint hard to move them, either. That many "helpers",working for you 24-7, taking cats, dogs, fish, turtles, birds, etc, you will have meat daily, and some of it can be "stored-alive" (like the fish, turtles, snakes and some types of birds, at least for a while.) You can do like the Koreans do, and tie up a dog or two, feeding them the guts of animals and birds, fish and bird heads, etc. So, along with having taken some livestock, early on, and either taking or having some grain, you can easily outlast 99% of the population, if you just pay attention, for the first 1-3 months. By then, you will have so much flesh food stored,and stored up(or know about )so much wild edible plants, that you will be fine ,until things have calmed down enough to make it feasible to (carefully) garden again. 1 year is all you'll have to survive the hard way. Either nearly everyone will either be dead, or something else will have restored the peace. Either way, it will be ok to have scattered, small, hidden garden plots. You dont need more than 4x8 ft of the better plants, in 4-5 different places, and 8-10 such aint hard to tend. If half are found, you still have plenty. Of course, you will intelligently and silently hunt down, trap, lay-for anyone or any thing that's raiding your garden. After a year, such will be VERY rare, though.