Hmm, I just plant them in the ground or in a pot. I have not heard or noticed that it would be better blooming in a pot.

Containering does allow you to move the pot around throughout the growing season in the eternal chase for sunlight though.

You kind of have to select pot styles that are wide-ish as the roots are shallow and tend to grow horizontally near the top few inches.

And of course, I am assuming you are not growing from cuttings but rather buying one from a plant nursery.