Q.My desert rose is dropping healthy leaves, what could be causing this?
My desert rose has been dropping healthy green leaves. No pests visible under microscope. Nor are there signs of root rot. I water once a week letting it completely drain before placing on drip tray. It’s planted in the required soil mixture. Appears to be healthy in every way besides the dropping of healthy leaves.

Certified GKH Gardening Expert
I am seeing the tale-tell signs of a nitrogen deficiency. If you do not feed this regularly, then it is likely that there is an actual deficiency.
If you can test the pH of the soil, and the EC as well, then you can get a better idea of what is going on. If the soil is too alkaline, then the plant will not be able to take up nitrogen. If your EC is higher than .5 then there will be plenty of nutrients, and if it is less then that, you may want to feed it.
This article will give you more information on the care of these: https://www.gardeningknowhow.com/ornamental/flowers/desert-rose/caring-for-desert-rose-plants.htm