With temperatures in those ranges canna will need more water that you might think. They are after all a tropical plant. Lots of sun, heat, and lots and lots and lots more water. Soak the soil at the base of the plants for an hour or more if possible, every other day in that kind of heat.

Thanks FBG. I think I'll give that a shot. I've been watering them every 3-4 days in the heat, since looking at them, they don't seem stressed. But I'll try watering more. I enjoy watering stuff anyways.

I got some new canna for free from Craigs list. I have no idea of what they are as the flowers where all gone. But I do know that unlike mine, the leaves are very thick, they were planted in full sun, reached full height weeks ago and the yard they came from,,,, I'm not saying it was neglected, but I don't think they got much care.

They're growing very nicely now. I guess I'll have to see later what they are....

I have had my cannas in the sun here in florida when it gets 95 and above I water them but with my saved rain water. I found They grow faster with rain water opposed to town water.
I also use superthrive has b vitamins , it seems to help them through the extreme heat or cold and they grow taller . hope some of this helps.
Joscelyne~

Joscelyne thanks. As a matter of fact, that's on my list of winter projects. To install a rain barrel system.

What a waste to have all that good water just run down the side of the house and into the ground. And then pay for water from the city, that plants don't even like. There is a huge difference in the yard after a good rain vs after of good hose watering.

I'm thinking of a six barrel system with an electric boost pump and "drip" system for my key plants...