@lovinglyjeno I'm having this same issue and some of the plants never bloom and the others rarely bloom. I currently have the Seasons pack and no mods or CCs installed. I've had my plants for over a full Sims year and have only had to water like twice. They are sheltered without any special planters. I have maxed out the gardening skill and just got the Green Thumb rewards trait. I have "good soil" turned on. I've tried moving a couple in Build Mode because some were also going back to Seed status but everything is evolving. It rarely lets me fertalize, too. Weeds will pop up, bugs will pop up.
Could it be because she's a vampire? I've even tried having her start gardens on other lots in other worlds thinking it was the world I have her living in. I'm so frustrated. How am I supposed to harvest snapdragons and lilies for the Grim Rewards Event if they never bloom?