9 years, Cape Coral!
If you look at Desert Rose images on line you'll see many of them growing in very large containers or tubs. They have these huge calluses or big above soil tuber type deal. They really flower well in tight containers.
They are tropical plants so I doubt that the nursery in NC had them for very long.
But regardless, mine in Florida loved the heat but didn't care for more then 3-4 hours of direct sun. The sun is just too strong down there. Mine always dropped their leaves in October/November and put on new ones in early February or so. They seemed to flower better for me when I gave them a teaspoon of slow release fertilizer. I used "Dynamite" 20-20-20. I gave that to them when they started putting out new leaves.
I got flowers on about 50% of the branch tips and 5-8 flowers per.
Good luck with yours.
They rot easily during the rainy season, especially if drainage is compromised.
