they should do well in a large pot. these plants to do well outdoors. They can reseed and you will easily get new plants from those as well.

I remember seeing two daturas, each in a one gallon pot, in the university herbarium in mid March. They were flowering, so if you have anything larger than a one gallon, they should be happy!

I threw a whole lot of seed on the ground two years ago, and they grew absolutely beautiful. They set seed, and I tossed the seeds on the ground. Nothing came up last year. Lo and behold, I've been pulling datura seedlings since our warm spell two weeks ago. A good omen for a hot and wet season, I'm hoping!