• Plant them in shade. What you're seeing in the photo is morning sunlight, but after noon, they go into the shade of the house. That is, they're planted along the eastern edge of my house. I've tried planting them elsewhere, but they won't last. They get ratty, look terrible and never come back if you plant them in full sunlight. Give 'em shade!
• Give them water. The tiny area where the cannas are has always been a boggy area, going back to when I had grass there, many years ago. Cannas love water. If you have an area that collects water and is in the shade, put your cannas there.
• Give them rich soil. I like to say that my cannas aren't planted in Arizona, they're planted in potting soil in holes in Arizona. That is, the native soil was dug up and moved elsewhere a long time ago. I have also added a LOT of coffee grounds (I got bags of it for free at Starbucks). I add dry-release fertilizer, even the little houseplant spikes.
• Cut them back severely. These plants were cut down to the ground two months ago. The best-looking foliage comes from the new growth. After a stalk blooms, I cut it to the ground. When in doubt, cut a stalk to the ground. Believe me, it will grow back!
• Plant them where you can do minor trimming with ease. To look their best, cannas need constant fussing. I have trimmers handy, and whenever I go out with my coffee, I snip a bit. It's like tending a flower garden, except that you're looking for foliage, not flowers.
When I first planted these Canna Tropicannas, many years ago, they were only available through mail order. Now I see them everywhere. By the way, you can save yourself some money and hassle by just buying the bulb (actually, it's a rhizome, but it's kind'a the same thing, like tulips). Give them a good home, then stand back. Believe me, they'll grow!