This is the first picture from that post. It looks sort of Carissa macrocarpa-esque: there are several strange cultivars with which I'm not familiar. Does it have any thorns? Milky sap if a leaf is broken?

Well, it´s dead. But some plants in the same container seem to be doing OK, which have obviously had the same conditions. We can only really guess at the reason, could even be some obscure infection, or no real reason at all, but like other folks say, your soil does look a bit suspect. There are as many favourite soil mixes as there are growers, and I have now firmly settled on a well-draining gritty mix with a good proportion of limestone for my desert cacti, with just a little organic material. I totally avoid soggy peat, which means any commercial ´cactus mix´, as they are invariably full of peat or even worse - ´forest product´- read sawdust. A gritty mix in unglazed terra cotta pots will set you up. Err on the dry side rather than overwater - it is quite difficult to kill a cactus through underwatering. They are succulents - they will store water when it rains heavily, then be well able to survive drought conditions for weeks or even months.

i did mine on july 24th ... and it took about 3 weeks to recover gang busters .... BUT.. that was august in MI ... i suspect.. if i did it in now or in sept.. in my MI ... with nights presumably getting cold.. it would have been a much slower process.. not to mention days getting shorter .... etc ... BUT I DONT KNOW WHERE YOU ARE i took everything down to about 4 inches ... you could do every other branch down.. and see how it responds ... frankly.. by late sept.. i would me more worried about an early surprise frost.. than whether my annuals still would be looking great ... carp.. now you have something else to worry about.. depending where you are .... lol ken ps: should have started your own post .... in the annuals forum ... with a pic of yours ... bet you would have gotten a lot more replies ....

Jena, my Perle d’Or did the bud drop thing it’s first year, the whole year. A lot of my roses also had chlorosis, including Perle d’Or, even though they were getting regular Magnesium-sulfate and I was alternating between Miracle Grown and a seaweed fertilizer, all in the hopes of curing them of chlorosis. Mostly it was the Polyanthas and Multifloras that had this problem. Finally I sent in a sample for a soil test. I had plenty of all the minerals and nutrients except for Nitrogen (which I already knew since its obviously devoid of any organics and so I was fertilizing) and absolutely zero Manganese (Mn) detected. Once I put a teaspoon of Manganese Sulfate dissolved in a gallon of water on each rose last fall the chlorosis completely disappeared and Perle d’Or stopped dropping buds. I will now do this once or twice a year; not too often since Mn is a minor nutrient and too much can be toxic. The Miracle grow I was using did have trace Mn, but somehow it wasn’t enough. I wonder if my soil was just binding it up? This just demonstrates that bud drop could be due to lack of an essential nutrient. It might not necessarily be Manganese for you. But since you mention the Kellogg soil might not be that great, I would give it a nice dilute liquid fertilizer once a week and see if it cures it.