I'd almost have to stop in mid sentence and ask her when she's watering her plants, if she'd like to be alone?!
Maybe that's part of her therapy??? It doesn't sound very therapeutic to me though. You know therapists are human and like us they tend to have moods and whatnot, but this behavior sounds very unprofessional. I would either talk to her about this, or just seek another therapist.
Best wishes to you and Hugs, Teri