Wow, they are beautiful! I've never tried them here, but after seeing them in the database and yours above, I think I will.
Have you tried starting the seeds in the fall, protecting them from the cold over winter and then enjoying the blooms through spring? This is what I do with Nasturtiums here, and it took me quite a while - years in fact - to figure out this was the way to go with them. They just peter out so fast once the humidity returns and the nights are warm.
To me, anything that says "zone 5b - 10" means one thing, we're at the very limit of that plant's comfort zone. So if you can carry young plants through the winter and get them blooming in February, they will give you great bang for your buck (or reward for your work and care). I think trying to keep a temperate plant going through a tropical summer just ain't gonna fly.
I have had limited success getting lavender to survive through a summer, by giving it the driest, coolest spot I can - under my big stand of bamboo. It goes semi-dormant and perks up magically once the nights cool off in the fall. This might work for summering over your ice plants, too.
I'm sure going to give your Chamomile tea trick a try!
