The nice USDA lady mentions that the size they are putting up is a good size for a home garden. The farmers' being larger of course. The hoophouse program is based on 20'x100' hoophouses. These do a wonderful job in our climate of letting you do 4 season gardening. (yes, I know the link isn't live yet, but soon!)
You won't do tomatoes and eggplant in December, but you can do lots of greens and cabbages and root crops. And those are just as wonderful...fresh from your yard!