Q.Best Slow-release Fertilizer For Large Potted Desert Rose Outdoors In South Florida?
It is much larger now than in picture. If can find pot large enough for root caudex, should be repotted. Outdoor soil too wet, too low for proper drainage.
Certified GKH Gardening Expert
Typically, you won't want to feed with a slow release. It will feed during the winter months, which you do not want. Usually, you will feed with a half strength of 20-20-20 during the active growing season.
Your moist soil will be more of an issue than feeding will be, however. They don't really NEED to be fed, though. They can usually get enough feed from the soil. Speaking of... These will appreciate a cactus or succulent soil!
Here is an article that will offer more care tips:
https://www.gardeningknowhow.com/ornamental/flowers/desert-rose/caring-for-desert-rose-plants.htm