Hi @aaronrulz I hope I can be of some help as my main Sim is a gardener/flower arranger with a greenhouse and sheltered plants. Here is my experience:
Sheltered plants bloom all year round regardless of the season.
The bugs I still have issues with are that plants will revert back to dirt piles or become bare often (but if you have no issue with cheats then you can choose the blooming state of your plants of this happens). And harvestables ending up in the household inventory.
Despite the bugs, I'm still finding the gardening/flower arranging quite fun. :smile: