oh don't worry - everything that is out there is going to have a chance to sprout no matter what anyone says to the contrary...
I'm planning to sow some lettuce and maybe some other greens in my (unheated hoop house) soon -- last spring some lettuce that I had planted the previous July came back and grew into beautiful heads; I never did a later planting last year, so I'm going to try seeding it and hopefully will get very early lettuce.
This is some of the lettuce that re-grew for me (the photo was taken on 5/20/2011)