Not sure if this will be of much help but it's something that's helped my gardening
My plants will occasionally revert to dirt but they do become bushes and trees later in the morning to early afternoon unless they went out of season. The lower the quality of my plant the more often they get weeds, bugs and revert or just suddenly start to die.
I shift + click my plants that give the most issues be it weeds or bugs or near death and click set stage and set it to ready to evolve and then evolve it as normal. That saves every plant except the super dead ones.
Rabbits and birds help as does a sim who can just tend garden. If my plants aren't evolving quickly with a level 10 Gardner on great soil I shift click them along to avoid the problems and it usually solves the revert to dirt. At least for me this has worked and my gardens are all producing well in every world now.