Did you check them at different times? They only open after certain time, hence the name. I grew up in Asia where they really opened around 4pm, but overhere because of longer days in the summer, I have heard that they open slightly later, like 6pm. I don't know about Florida.

As for heat, I think they should be ok. In SE Asia, the average temperature is around 90F, and there are only 2 seasons: hotter or hottest. They grow like weeds there.

Hi Dave. Thank you for the reply. I've looked at them as late as around 7 p.m. and a lot of them are still unopened. Then in the morning, I can't tell which are the spent blooms and which are new buds that would open later that day. Maybe mine open really late due to the heat (our overnight lows are in the 80s). Maybe they're really Ten O'Clocks, lol!

LOL! Maybe they still have their jet lag after moving here. :-)

Yeah, here in SE Asia, they do grow like weeds. Very easy to grow and propagate. And they smell wonderful.