There are dozens of enormous Beaucarnea on the island here...they are caudiciforms and seem tough as nails. I think to bloom they need to be in the ground and a certain size. I saw lots in bloom this spring, all in the ground, all massive. I think like other caudiciforms, they will form a more massive "foot" when the tops of the plant are lobbed off...like a desert rose. There is one here in my neighborhood that has obviously been aggressively trimmed over the years and its "foot" has to be at least 6 feet in diameter. It is shockingly large.