Lemon verbena lists at zone 9 or 10 hardy and doesn't tolerate any frost. It gets pretty frosty (aka water freezes) in my attached and unheated sunroom/porch during the coldest parts of winter. I'm in Western NY State, just to your southeast and probably in a slightly warmer zone than you. I personally wouldn't try it. I generally count on at least zone or 2 bump in my unheated area and wouldn't count on more than that to be safe.

Last winter was tough. I had winter kill off many plants I've never lost in any winter before. It was exceptionally hard. I don't mind winter cold and snow but last year was very long as well as harsh. Let's hope for any early spring this next year!

FataMorgana