I have avoided the bright blue Corydalis flexuosa cultivars (Blue Panda, China Blue, etc) for the same reason - intolerance to summer heat/humidity. I have read that Corydalis elata is less fussy about heat/humidity, but I haven't tried it yet. It is also a bright blue. I have seen it available online. Also there is a hybrid between the C. flexuosa and C. elata called Porcelain Blue which is supposed to do a lot better in the south. Again, I haven't tried it personally yet. I see it available online from a number of nurseries. You might check either of them out.
