This is my first year with an in-ground garden in Zone 6a! Here's what I've got:
-Plant more peppers, I eat a lot of peppers and could use more
-Plant beans/peas earlier
-Plant okra later
-Only ONE cucumber plant!!! Just one! No one needs more than one!
-More ground cherries, they did great and I love 'em
-Wouldn't bother with celery again, probably
-Would give radishes another shot, they did okay. I'd do kohlrabi again too
-Planted too many types of lettuce
A recent study suggested that the safe upper limit in wet bulb conditions might be closer to 88F. Link to an article discussing the research