For my first year of experience(at least what really worked early 2010), the clue is to look at the middle of February, if the weather forecast promise no more frost the next week, then I dare and start sowing seeds outside,if a sudden frost arrives the next weeks I cover my plants. 

Asparagus – Jan 15->Feb 15th

Beans ( lima and snap ) – March 1->April 7th and Sept 1->Sept 21

 Beets – Feb 1->28 & Sept 21->Oct 15thBroccoli – Jan 21->Feb21 & Sept 15th ->Oct 15th

Cabbage – Jan 21->Feb 21 & Sept 15th ->Oct 15th

Cantalope – March 21->Jun 30th

Cauliflower – Jan 21->Feb 21 & Sept 15->Oct 15th

Carrots- Oct 15->Nov 15th

Collards – Jan 21->Feb 15th & Sept 15->Nov 1

Corn – Mar 1->March 31

Cucumber – Mar 21->Apr 30

Eggplant – March 21->Jul 7th

Kohlrabi – Jan 21->Feb 28th & Sept 21->Oct 31

Lettuce – Jan 21->Feb 28th & Oct 7->Nov 30

Muskmelon or Watermelon – March 21->Jun 30th

Okra – Apr 1st->Jul 31st

Onions – Jan 15->Feb 15

Peas, snap – Sept 21->Oct 15th

Peppers – March 15->April 30th

Potatoes – Feb 1->Feb 15th

Pumpkin – Mar 15->Jul 15

Radish -> Feb 1 -> Mar 7th & Sept 1->Nov 15th

Southern peas – Apr 1->Aug 21

Spinach – Oct 1->Nov 15th

Squash – Mar 15th ->Apr 30

Sweet potatoes – Apr 1->Jul 15th

Swiss Chard – Jan 21->Feb 15 & Sept 21->Nov 7

Tomatoes – Mar 1->Mar 31

Turnip – Feb 1 ->Feb 28th