This is a brief overview of organic vegetable gardening from the UGA Cooperative Extension:

http://pubs.caes.uga.edu/caespubs/pubcd/B1011/B1011.htm

They have also published a great guide for spring and fall vegetable planting:

http://pubs.caes.uga.edu/caespubs/pubcd/C963/C963VegeChart.pdf

For a more comprehensive guide to organic and sustainable gardening, visit the ATTRA site (National Sustainable Agriculture Information Service):

http://attra.ncat.org/