In my “Symmetric Warfare” post, I wrote

The best solution I’ve come up with is for people to camp out on farms and defend them…

The question is, how do you get from here to there? Lots of planning and cash is necessary to store enough food to feed not only the farmers, but volunteers from the city. Farms are so spread out that it would be hard to defend them all. One approach is to concentrate your defensive efforts on particular farms, which I will call “seed repositories.” A seed repository stores seed for planting crops for a group of farms, and serves as a refuge for nearby farmers. At the onset of a serious emergency, pre-arranged volunteers would come to each seed repository to help defend it. In return, the volunteers would be fed and sheltered (perhaps in tents) during the crisis.

Seed repositories might be financed in part by dues from memberships. After all, aside from the practical benefits of repositories, preserving the productive capacity of farms during times of disaster is a noble effort to be part of. It is also a worthy cause to donate to, and might draw substantial donations from wealthy people who worry about the future.