I love my Begonia grandis. I bought it five or six years ago from Lost Horizons nursery here in Ontario, and somewhat to my surprise it proved to be winter hardy here. The main plant did not reappear in the spring of 2022, but that proved to be an advantage, as now the tiny plants from the bulbils had a chance to develop. This year I have a big clump consisting of maybe six plants, and it is in bloom now. The begonia dukes it out for space with an Arum italicum marmorata, whose orange-red berries look great with the red highlights of the begonia foliage. I often thought I had lost the begonia, as it only appears around the first week of June. Does it come up earlier in warmer areas? I live in the rough equivalent of USDA z.5.
I will try to post some pictures from my phone, here or in a comment.