I want to start a thread about community gardening ideas for self-sufficiency. I want to know the best way I can provide a major portion of my diet with my community gardens.

Particularly I'm curious what my meals will look like. What is going to be on my plate for 3 meals a day, that contains enough calories, complete and balanced nutrition, and is delicious and a joy to eat? What should I plant and when to provide these things for myself and for my community all year long or for as much of the year as possible?

A great deal of work about complete home-grown diets has been done by Ecology Action, specifically using Biointensive techniques to grow the most food in the least amount of space.  The book One Circle describes some model diets and the space they require.  The model diets are meant as suggestions and definitely need improvement.  They are quite boring and also are deficient in calories and some nutrients (most especially Iodine and Vitamin B12).  It is very difficult to grow enough calories in a small space.

http://www.growbiointensive.org/

One Circle:  https://www.bountifulgardens.org/products/BEA-0370

Jon Jeavons' book "How to Grow More Vegetables..." about Biointensive growing is another good resource.

As someone who has done the community garden thing in a number of places,  you are unlikely to be able to feed yourself out of the typical community garden plot.   Even in California where I live despite being able to harvest tomatoes and peppers into November and even sometimes December the growing season in most places just isn't long enough and the size of the typical plot is too small to allow you real succession planting. 

What most of us shoot for is some combination of better tasting veggies and or ones that growing at home either reduced the worst pesticide crops or ones that growing in real soil will increase their nutritional value.

I completely agree with Michael.

Even using the most biointensive methods it takes a fair amount of space to grow enough food for even one person. Things like winter squash are critical to feed you through the winter but take up a lot of space. And it's not just about total area, but how you use it -- successions being absolutely critical.

That's not to say it wouldn't be fun and interesting to try! If it were me I'd look at the most efficient crops space-wise, and explore keeping things as vertical as possible. In fact, I wonder if you could grow something like a Delicata or Butternut squash on a trellis, with greens under neath. Some people do this for cucumbers, so I don't see why not.

There are also some community gardens which pool everyone's effort into one big garden -- there are one or two in Seattle but I forget the name. This would be much more efficient as long as the area was appropriate for the size of the community.

Under good growing conditions it takes a minimum of 4000 square feet per person to grow a diet using Biointensive methods.  If one can obtain sufficient organic materials for compost from off-site, the space needed may be less. 

Just adding this link to the thread as an inspirational read:  http://onwisconsin.uwalumni.com/features/a-taste-of-freedom/

A source of food that I find readily available in the city is tree fruits and nuts. In this area, there are many trees in people's yards that go un-harvested. There are many trees growing in common areas like parks, roadways, or canals that go un-harvested. Paying attention to those sources of food, and harvesting them can make a significant contribution to feeding a family. Refine the technique even more, by making agreements with the landowners to take care of the trees in exchange for the food they produce. Offer to clean up windfalls, or give them a couple bottles of juice made from the fruit of their tree. Don't overlook other forageables like blackberries, asparagus, mints, cattail pollen, rock doves,  etc.