Partial but fairly confident answer
I am pretty sure you are
Athens, Georgia.
Flying fortresses departed to "roam" the Stratosphere from me, but I'm too small to host even a 727.
The B-52s were formed in Athens, Georgia. The B-52 aircraft for which they are named is also called the Stratofortress. One of their songs is called Roam. Athens has a small airport with short runways; probably too short for a Boeing 727.
No one owns my tree, not even me.
Athens is home to The Tree That Owns Itself. In American law trees cannot literally own themselves.
I've induced far reaching hysteria and caused the most famous lucid dreams, but mostly only social wasps fear me.
Hysteria: Widespread Panic. Lucid dreams: Dreams So Real though R.E.M. seems kinda relevant too. The social wasps are probably something to do with the Georgia Tech Yellow Jackets -- this has been confirmed by OP, but if it's a reference to some particular match I haven't found it.
I've hosted a man with sparks and ultramarine women.
The man with sparks might be Mike "Phosphorescent" Houck ... OP says not, but I haven't found better candidates; there are bands called Pylon and Elf Power but those don't seem like improvements. The ultramarine women must be the Indigo Girls.