I read that fava beans' flowers become sterile if temperatures are sustained >80dF. I have fava beans given to me from a sub-tropical climate and wonder if I can grow them in temperature climate (hardiness zone 4/5). Reading about the plant it seems that I can and most people start growing them in the fall so they fruit in spring when temperatures aren't too hot. I wonder can the beans be planted now (late Spring / early Summer), and because they are perennial they will eventually fruit when temperatures are right?
I'm not sure how "perennial" they really are, despite numerous sources saying that, so it could be that if they grow to flowering maturity and the temperatures are too hot for fruiting the beans will simply die off and need to be started from scratch. That's what I'm wondering about.