with Jean, and it does sort of depend upon the variety of lavender you've got. I've had the odd one make it through the summer here, with cactus mix in the pot, elevated and kept as dry as possible in our humidity.
I buy it every year in the early spring, just because I love it. But more often than not it succumbs to the humidity in summer - root rot from not drying out enough, I think. Might try it in a hanging basket this year, in fact. My orchids do manage to dry out pretty well . . . even in summer.