That's what I've always heard - late bloomers even into September. I have a couple of vines going here in Philly and they have some buds on them now, but I don't know when they will finally turn into flowers. I got a pretty late start with them, sowing the seeds indoors around April 18 and planting them out (drat, didn't make a note) maybe 2 weeks later. I don't know if an earlier start would have made a difference, though, because the seedlings just flat-out refused to start growing until it got hot, and then FINALLY started taking off.