Summerkid: Winter, lol. I live in GA. Earthworms all year 'round!!
I have no problem keeping worms in my beds. Just have to add enough water and compost and there they are!
I did however remove the plastic from directly under the beds. I did not mention this, but I do it the 2nd planting. The first planting of the beds I leave it down. Then when I turn to refresh compost and add minerals or organics I dig down deep enough to lift up the weed barrier and rip it right out. It won't be needed any longer after the grass as died!
I have watched the Path to Freedom site for a couple years and admire them. It is amazing that on such a small piece of land (1/5) acre - including their home - that they are so productive. Of course they are blessed to be living in a mild climate and abe to grow year around. FYI, here is a newer (I believe): video:http://video.nytimes.com/video/2008/04/18/magazine/1194817108584/life-mostly-off-the-grid.html
I would love to be able to grow more 'in ground', but the gophers would have a field day. I have done stra bales this year and they worked quite well. Your raised beds look great. Are you making other changes to be off the grid, or primarily working on the food growing aspect? Any producers of eggs, milk, etc.?