Calceolaria mexicana is annual. I got it from my friend Glen who grew it from seed. Last year, I put the few plants I had in a container, and it was not particularly successful. This year, I was once again given a few small plants which I decided to put directly in the ground, and they did much better. Glen tells me that it comes back from seed year after year. He has some nice drifts in his own garden.
When you let it self-seed in the garden, the tricky part is to learn to recognize it in the spring, when it is just sprouting, in order not to weed it out. I have it in full sun where it is doing very well. I read, however, that it is recommended for shade. I checked with Glen and he says his is growing in half day sun. His plants that were in shadier spots did not self-seed. I put mine in full sun where it seems to be quite happy. Of course, we had a rather cool summer here. That might explain why it did well in full sun. It is obviously adaptable. My suspicion is that the hotter the situation, the more shade it likes.
It is an undemanding plant that brightens up any corner you put it in. I read that it is best to seed it directly where you want to grow it. The yellow is quite attractive. It is so bright, that in photos it tends to appear rather washed out. It is long blooming, still covered with flowers at the time of writing in mid-September. It is about 30 cm high and has been blooming since June. I think it is a good addition to the garden.